Misplaced Pages

#17982

80-456: Cartridges contain hundreds of meters of half-inch (12.65 mm) wide tape media wound onto a single reel. Mechanisms (a.k.a. tape drives , streamers) extract the tape from the cartridge and spool it up on a second reel in the mechanism, reading or writing data as the tape moves between reels. Robotic libraries exist that can hold hundreds or thousands of LTO cartridges and dozens of mechanisms. The original version of LTO Ultrium, called LTO-1,

160-546: A Class B fire rating , and can achieve a Class A rating when used in conjunction with specially designed roof assemblies. The use of wooden roof shingles has existed in parts of the world with a long tradition of wooden buildings, especially Scandinavia , and Central and Eastern Europe . Nearly all the houses and buildings in colonial Chiloé were built with wood, and roof shingles were extensively employed in Chilota architecture . Slate shingles are also called slate tiles ,

240-473: A magnetic tape . Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability. A tape drive provides sequential access storage, unlike a hard disk drive , which provides direct access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As

320-545: A PC and integrates with analytical software to evaluate the quality of tapes. This device is also rebranded as the Spectra MLM Reader and the Maxell LTO Cartridge Memory Analyzer. Proxmark3 and other generic RFID readers are also able to read data. The LTO cartridge label in tape library applications commonly uses the bar code symbology of USS-39 . A description and definition is available from

400-829: A Strontium Ferrite (SrFe) technology able, in theory, to store 580 TB per tape cartridge. Roof shingle A roof’s shingles are a roof covering consisting of individual overlapping elements. These elements are typically flat, rectangular shapes laid in courses from the bottom edge of the roof up, with each successive course overlapping the joints below. Shingles are held by the roof rafters and are made of various materials such as wood , slate , flagstone , metal , plastic , and composite materials such as fibre cement and asphalt shingles . Ceramic roof tiles , which still dominate in Europe and some parts of Asia, are still usually called tiles. Roof shingles may deteriorate faster and need to repel more water than wall shingles. They are

480-399: A cartridge is inserted. When a more thorough cleaning is required the drive signals this on its display and/or via Tape Alert flags. Cleaning cartridge lifespan is usually from 15 to 50 cleanings. There are 2 basic methods of initiating a cleaning of a drive: robot cleaning and software cleaning. In addition to keeping the tape drive clean, it is also important to keep the media clean. Debris on

560-763: A cleaning strategy that will prevent the drive from using the cleaning tape if it is not needed. In a change of strategy, HP LTO Gen 2, 3 and 4 drives will always clean when a Universal Cleaning Cartridge is inserted, whether the drive requires cleaning or not. As of 2019, compliance-verified licensed manufacturers of current LTO technology mechanisms are IBM , Hewlett-Packard , and Quantum , although both Hewlett Packard and Quantum have stopped new development of drive mechanisms. The mechanisms, also known as tape drives or streamers, are available in Full-height and Half-height form factors. These drives are frequently packaged into external desktop enclosures or carriers that fit into

640-499: A coiled serpent and is known as linear serpentine recording. When the first data band is filled (they are filled in 3, 1, 0, 2 order across the tape), the head assembly is moved to the second data band and a new set of wraps is written in the same linear serpentine manner. The total number of tracks on the tape is (4 data bands) × (11 to 52 wraps per band) × (8, 16, or 32 tracks per wrap). For example, an LTO-2 tape has 16 wraps per band, and thus requires 64 passes to fill. Since LTFS

720-476: A fixed ratio, commonly 2:1. See Compression below for algorithm descriptions and the table above for LTO's advertised compression ratios. The units for data capacity and data transfer rates generally follow the "decimal" SI prefix convention (e.g. mega = 10), not the binary interpretation of a decimal prefix (e.g. mega = 2). Minimum and maximum reading and writing speeds are drive-dependent. Drives usually support variable-speed operation to dynamically match

800-662: A large file or a large selection of files (up to 1.5 TB for LTO-5 or 2.5 TB for LTO-6) to an LTFS-formatted tape, allows easy exchange of data to a collaborator or saving of an archival copy. Throughout the history of the format, there have been six compliance-verified, licensed manufacturers of LTO technology media: EMTEC , Imation , Fujifilm , Maxell , TDK , and Sony . All other brands of media are (or were) manufactured by these companies under contract. Since its bankruptcy in 2003, EMTEC no longer manufactures LTO media products. Imation ended all magnetic tape production in 2011, but continued making cartridges using TDK tape for

880-605: A material locally available. The type of shingle is taken into account before construction because the material affects the roof pitch and construction method: Some shingles can be installed on lath where others need solid sheathing (sheeting) on the roof deck . All shingle roofs are installed from the bottom upward beginning with a starter course and the edge seams offset to avoid leaks. Many shingle installations benefit from being placed on top of an underlayment material such as asphalt felt paper to prevent leaks even from wind driven rain and snow and ice dams in cold climates. At

SECTION 10

#1733094088018

960-446: A result, tape drives have very large average access times . However, tape drives can stream data very quickly off a tape when the required position has been reached. For example, as of 2017 Linear Tape-Open (LTO) supports continuous data transfer rates of up to 360 MB/s, a rate comparable to hard disk drives. Magnetic-tape drives with capacities of less than one megabyte were first used for data storage on mainframe computers in

1040-477: A robotic tape library. In the course of its existence, LTO has succeeded in completely displacing all other low-end/mid-range tape technologies such as AIT , DLT , DAT/DDS , and VXA . And after the exit of Oracle StorageTek T10000 of the high-end market, only the IBM 3592 series and LTO are still under active development. LTO also competes against hard disk drives (HDDs), and its continuous improvement has prevented

1120-672: A silver-like tone. Types include hand-split resawn shakes, tapersplit shakes or tapersawn shakes. Composite or synthetic shingles are a relatively new type of shingle material that are made from a blend of materials, including asphalt, fiberglass, and other polymers. These shingles are designed to mimic the look of natural materials such as wood, slate, or clay and aim to increase the durability, strength, and resistance to weather elements relative to these natural materials. Some examples of manufacturers of synthetic or composite roof shingles are DaVinci Roofscapes or Unified Steel. Rubber shingle roofs are typically made from 95% recycled material from

1200-419: A single, one-way, end-to-end pass that is called a "wrap". The tape head shifts laterally to access the different wraps within each band and also to access the other bands. Writing to a blank tape starts at band 0, wrap 0, a forward wrap that runs from the beginning of the tape (BOT) to the end of the tape (EOT) and includes a track that runs along one side of the data band. The next wrap written, band 0, wrap 1,

1280-456: A slow disk drive. Data tape drives may use advanced data integrity techniques such as multilevel forward error correction, shingling, and linear serpentine layout for writing data to tape. Tape drives can be connected to a computer with SCSI , Fibre Channel , SATA , USB , FireWire , FICON , or other interfaces. Tape drives are used with autoloaders and tape libraries which automatically load, unload, and store multiple tapes, increasing

1360-490: A standard XML schema , is readable by any LTFS-aware system and can be modified separately from the data it describes. The Linear Tape File System Technical Work Group of the Storage Networking Industry Association (SNIA) works on the development of the format for LTFS. Without LTFS, data is generally written to tape as a sequence of nameless "files", or data blocks, separated by "filemarks". Each file

1440-403: A take-up reel. When a cartridge is not in a drive, the pin is held in place at the opening of the cartridge with a small spring. A common reason for a cartridge failing to load into a drive is the misplacement of the leader pin as a result of the cartridge having been dropped. The plastic slot where the pin is normally held is deformed by the drop and the leader pin is no longer in the position that

1520-399: A tape appear to behave like a disk, it does not change the fundamentally sequential nature of tape. Files are always appended to the end of the tape. If a file is modified and overwritten or removed from the volume, the associated tape blocks used are not freed up: they are simply marked as unavailable, and the used volume capacity is not recovered. Data is deleted and capacity recovered only if

1600-511: A tape written on any one vendor's drive should be fully readable on any other vendor's drive that is compatible with that generation of LTO. LTO Ultrium tape is laid out with four wide data bands sandwiched between five narrow servo bands. The tape head assembly, that reads from and writes to the tape, straddles a single data band and the two adjacent servo bands. The tape head has 8, 16, or 32 data read/write head elements and 2 servo read elements. The set of 8, 16, or 32 tracks are read or written in

1680-445: A time, via a non-contacting passive 13.56 MHz RF interface. This memory is used to identify tapes, to help drives discriminate between different generations of the technology, and to store tape-use information. Every LTO drive has a cartridge memory reader in it. The non-contact interface has a range of 20 mm. External readers are available, both built into tape libraries and PC based. One such reader, Veritape, connects by USB to

SECTION 20

#1733094088018

1760-499: A very common roofing material in the United States . Shingle is a corruption of German Schindel meaning a roofing slate. Shingles historically were called tiles, and shingle was a term applied to wood shingles, as is still mostly the case outside the US. Shingles are laid in courses , usually with each shingle offset from its neighbors. The first course is the starter course and

1840-479: A while. In 2017 they withdrew from all data storage markets, renaming themselves Glassbridge Enterprises. TDK withdrew from the data tape business in 2014. Maxell produced cartridges up to and including generation 6 in 2012, but has since withdrawn from the market. Verbatim and Quantegy both licensed LTO technology, but never manufactured their own compliance-verified media. As of 2019, only Fujifilm and Sony continue to manufacture current LTO media. In addition to

1920-412: A write-protect switch in the bottom-left corner, although it is easily overridden by the user and doesn't provide any protection from accidental deletion by, for example, misidentification of a cartridge. An LTO-3 or later drive will not erase or overwrite data on a WORM cartridge, but will read it. A WORM cartridge is identical to a normal tape cartridge of the same generation with the following exceptions:

2000-412: Is AES - GCM , which is an authenticated, symmetric block cipher. The same key is used to encrypt and decrypt data, and the algorithm can detect tampering with the data. Tape drives, tape libraries, and backup software can request and exchange encryption keys using either proprietary protocols, or an open standard like OASIS 's Key Management Interoperability Protocol . The LTO-5 specification introduced

2080-422: Is a reverse wrap (EOT to BOT) and includes a track along the other side of the band. Wraps continue in forward and reverse passes, with slight shifts toward the middle of the band on each pass. The tracks written on each pass partially overlap the tracks written on the previous wrap of the same direction, like roof shingles . The back and forth pattern, working from the edges into the middle, conceptually resembles

2160-438: Is always an even number). LTO tape is designed for 15 to 30 years of archival storage. If tapes are archived for longer than 6 months they have to be stored at a temperature between 16 and 25 °C (61 and 77 °F) and between 20 – 50% RH. Both drives and media should be kept free from airborne dust or other contaminants from packing and storage materials, paper dust, cardboard particles, printer toner dust etc. Depending on

2240-421: Is an open standard, LTFS-formatted tapes are usable by a wide variety of computing systems. The block structure of the tape is logical so interblock gaps, file marks, tape marks and so forth take only a few bytes each. In LTO-1 and LTO-2, this logical structure has CRC codes and compression added to create blocks of 403,884 bytes. Another chunk of 468 bytes of information (including statistics and information about

2320-585: Is in how they are made, with shingles always being sawn and shakes normally being split, at least on one side. A wood shake is often more textured, as it is split following the natural grain of the wood rather than sawn against it like the shingle. Untreated wood shingles and shakes have long been known as a fire hazard and have been banned in various places, particularly in urban areas where exterior, combustible building materials contribute to devastating fires known as conflagrations . Modern pressure-impregnated fire retardant treated wood shakes and shingles can achieve

2400-431: Is typically an archive of data organized using some variation of tar format or proprietary container formats developed for and used by backup programs. In contrast, LTFS utilizes an XML-based index file to present the copied files as if organized into directories. This means LTFS-formatted tape media can be used similarly to other removable media ( USB flash drive , external hard disk drive , and so on). While LTFS can make

2480-464: Is very similar to the algorithm ALDC which is a variation of LZS . LTO-1 through LTO-5 are advertised as achieving a "2:1" compression ratio, while LTO-6 and LTO-7, which apply a modified SLDC algorithm using a larger history buffer, are advertised as having a "2.5:1" ratio. This is inferior to slower algorithms such as gzip , but similar to lzop and the high speed algorithms built into other tape drives. The actually achievable ratio generally depends on

Linear Tape-Open - Misplaced Pages Continue

2560-417: Is when the slates themselves begin to break up. The lower parts of a slate may break loose, giving a gap below a slate. Commonly the small and stressed area above the nail hole may fail, allowing the slate to slip as before. In the worst cases, a slate may simply break in half and be lost altogether. A common repair to slate roofs is to apply ' torching ', a mortar fillet underneath the slates, attaching them to

2640-426: Is within one track. Also, when data is written to the tape it is verified by reading it back using the read heads that are positioned just "behind" the write heads. This allows the drive to write a second copy of any data that fails the verify without the help of the host system. While specifications vary between different drives, a typical LTO-7 drive will take about 15 seconds to load the tape and 20 seconds to unload

2720-442: The 1950s, starting with the open reel formats IBM 7-track and later IBM 9-track . In the mid-1980s, smaller, enclosed, single-reel cartridge formats were developed by IBM and DEC . Although the physical tape was nominally the same width in these new formats and the preceding open-reel formats, the technologies and intended markets were significantly different and there was no compatibility between them. The IBM 3480 tape format

2800-466: The 1950s. As of 2018 , capacities of 20 terabytes or higher of uncompressed data per cartridge were available. In early computer systems, magnetic tape served as the main storage medium because although the drives were expensive, the tapes were inexpensive. Some computer systems ran the operating system on tape drives such as DECtape . DECtape had fixed-size indexed blocks that could be rewritten without disturbing other blocks, so DECtape could be used like

2880-641: The Automatic Identification Manufacturers (AIM) specification Uniform Symbol Specification (USS-39) and the ANSI MH10.8M-1993 ANSI Barcode specification. The tape inside an LTO cartridge is wound around a single reel. The end of the tape is attached to a perpendicular leader pin that is used by an LTO drive to reliably grasp the end of the tape and mount it in a take-up reel inside the drive. Older single-reel tape technologies, such as 9-track tape and DLT , used different means to load tape onto

2960-427: The battens. This may apply as either a repair, to hold slipping slates, or pre-emptively on construction. Where slates are particularly heavy, the roof may begin to split apart along the roofline. This usually follows rot developing and weakening the internal timbers, often as a result of poor ventilation within the roof space. An important aspect to slate roofs is the use of a metal flashing which will last as long as

3040-401: The cartridge memory identifies it to the drive as WORM, the servo tracks are slightly different to allow verification that data has not been modified, the bottom half of the cartridge shell is gray, and it may come with tamper-proof screws. WORM-capable drives immediately recognize WORM cartridges and include a unique WORM ID with every dataset written to the tape. There is nothing different about

3120-528: The classic appearance of traditional slate, cedar shingles, and other materials. Metal shingles are extremely fire resistant, so are used in fire prone areas. Plastic has been used to produce imitation slate shingles. These are lightweight and durable, but combustible. Also, they are very lightweight and are one of the cheapest shingles to have installed. Cedar shingles are resistant to rot and commonly available in lengths of 18 and 24 inches (460 and 610 mm). These fade gradually from natural wood colored to

3200-415: The compressibility of the data, e.g. for precompressed data such as ZIP files, JPEG images, and MPEG video or audio the ratio will be close to or equal to 1:1. New for LTO-3 was write once read many (WORM) capability. This is useful for legal record keeping, and for protection from accidental or intentional erasure, for example from ransomware , or simply human error. Standard LTO cartridges do include

3280-612: The data cartridges, there are also Universal Cleaning Cartridges (UCC), which work with all drives. All formats use the same cartridge dimensions, 102.0 mm × 105.4 mm × 21.5 mm (4.02 in × 4.15 in × 0.85 in). The colors of LTO Ultrium cartridge shells are mostly consistent, though not formally standardized; HP is the notable exception. Sometimes similar, rather than identical, colors are used by different manufacturers (slate-blue and blue-gray; green, teal, and blue-green; dark red and burgundy). WORM (write once, read many) cartridges are two-tone:

Linear Tape-Open - Misplaced Pages Continue

3360-454: The data rate flow. This nearly eliminates tape backhitching or "shoe-shining", maximizing overall throughput and device/tape life. The LTO Consortium provide a roadmap of future generations, which state that LTO-10 is expected to have 36 TB of storage and LTO-14 potentially 576 TB. In contrast to other tape technologies, an Ultrium cartridge is rigidly defined by a particular generation of LTO technology and cannot be used in any other way (with

3440-413: The data transfer rate falls below the minimum threshold at which the tape drive heads were designed to transfer data to or from a continuously running tape. In this situation, the modern fast-running tape drive is unable to stop the tape instantly. Instead, the drive must decelerate and stop the tape, rewind it a short distance, restart it, position back to the point at which streaming stopped and then resume

3520-466: The drive expects it to be. The magnetic servo tracks on the tape are factory encoded. Using a bulk eraser, degaussing, or otherwise exposing the cartridge to a strong magnetic field, will erase the servo tracks along with the data tracks, rendering the cartridge unusable. Erasing the data tracks without destroying the servo tracks can be done with an LTO drive or with special equipment. The erasing head used in these erasers has four magnetic poles that match

3600-443: The drive that wrote the data and when it was written) is then added to create a "dataset". Finally error correction bytes are added to bring the total size of the dataset to 491,520 bytes (480  KiB ) before it is written in a specific format across the eight heads. LTO-3 and LTO-4 use a similar format with 1,616,940-byte blocks. The tape drives use a strong error correction algorithm that makes data recovery possible when lost data

3680-465: The drives and/or tapes and can be ignored or enabled. Compression and encryption can also be performed in software prior to the data being sent to the tape drive. However, the partitioning function can only be done in hardware, and the WORM feature requires special WORM tapes. The original LTO specification describes a data compression method LTO-DC , also called Streaming Lossless Data Compression (SLDC). It

3760-400: The drop in disk drive prices made such alternatives obsolete. As some data can be compressed to a smaller size than the original files, it has become commonplace when marketing tape drives to state the capacity with the assumption of a 2:1 compression ratio; thus a tape with a capacity of 80 GB would be sold as "80/160". The true storage capacity is also known as the native capacity or

3840-424: The exception of LTO-M8, see below). While Ultrium drives are also defined by a particular generation, they are required to have some level of compatibility with older generations of cartridges. The rules for compatibility between generations of drives and cartridges are as follows: Within the compatibility rules stated above, drives and cartridges from different vendors are expected to be interchangeable. For example,

3920-474: The fiber in the cement material was asbestos , the use of which has been banned since the 1980s, for health reasons. The removal of shingles containing asbestos requires extra precautions and special disposal methods. Metal shingles are a type of roofing material that offers the appeal of traditional shingles, such as wood, tile, and slate, while providing high fire resistance and durability. They are crafted from durable heavy-gauge aluminum and designed to emulate

4000-444: The generation of LTO technology, a single LTO tape should be able to sustain approximately 200-364 full file passes. There is a large amount of lifespan variability in actual use. One full file pass is equal to writing enough data to fill an entire tape and takes between 44 and 208 end-to-end passes. Regularly writing only 50% capacity of the tape results in half as many end-to-end tape passes for each scheduled backup, and thereby doubles

4080-939: The initial plans, only Ultrium was ever produced. So, in common usage, LTO refers to just the Ultrium form factor. Another proposed variation was to have different length tapes. The first generation of Ultrium was going to be available with four types of cartridges, holding 10 GB, 30 GB, 50 GB, and 100 GB. However, only the full length 100 GB tapes were ever produced. As of 2020, nine generations of LTO Ultrium technology have been made available and five more are planned. Between generations, there are strict compatibility rules that describe how and which drives and cartridges can be used together. While data capacity and speed figures vary with uncompressed or compressed data, most manufacturers list compressed capacities and speeds on their marketing material. Capacities are often stated on tapes assuming that data will be compressed at

SECTION 50

#1733094088018

4160-424: The last being a ridge course or ridge slates for a slate roof. The ridge is often covered with a ridge cap , board , piece , or roll , sometimes with a special ridge vent material. Roof shingles are almost always highly visible and so are an important aspect of a building's aesthetics in patterns, textures and colors. Roof shingles, like other building materials on vernacular buildings, are typically of

4240-477: The late 1990s, Quantum's DLT and Sony's AIT were the leading options for high-capacity tape storage for PC servers and UNIX systems. These technologies were tightly controlled by their owners and consequently, there was little to no competition between vendors and the prices were relatively high. Seeing an opportunity, IBM, HP and Seagate formed the LTO Consortium, which introduced a more open format focusing on

4320-479: The long-chain petroleum hydrocarbons, while wood shingles are protected by natural oils in the cellulose structure. Over time in the hot sun, these oils soften and when rain falls the oils are gradually washed out of the shingles. During rain, more water is channeled along eaves and complex rooflines, and these are subsequently more prone to erosion than other areas. Eventually the loss of the oils causes asphalt shingle fibers to shrink and wood shingles to rot, exposing

4400-415: The media can be deposited onto drive components that are in contact with the tape. This debris can result in increased media wear which generates more debris. Removing excessive debris from tape can reduce the number of data errors. Cleaning of the media requires special equipment. These cleaners are also used by Spectra Logic to clean new media that is marketed as "CarbideClean" media. HP LTO Gen.1 drives have

4480-624: The minimum recommended roof pitch is 4:12 without additional underlayment materials. In the United States, fiberglass-based asphalt shingles are by far the most common roofing material used for residential roofing applications. In Europe, they are called bitumen roof shingles or tile strips, and are much less common. They are easy to install, relatively affordable, last 20 to 60 years and are recyclable in some areas. Asphalt shingles come in numerous styles and colors. The protective nature of paper and fiberglass asphalt shingles primarily comes from

4560-418: The nail heads under the shingles. Once the nail heads are exposed, water running down the roof can seep into the building around the nail shank, resulting in rotting of underlying roof building materials and causing moisture damage to ceilings and paint inside. Two basic types of wood shingles are called shingles and shakes . Wood shakes are typically longer and thicker than wood shingles. The main difference

4640-669: The operation. If the condition repeats, the resulting back-and-forth tape motion resembles that of shining shoes with a cloth . Shoe-shining decreases the attainable data transfer rate, drive and tape life, and tape capacity. In early tape drives, non-continuous data transfer was normal and unavoidable. Computer processing power and available memory were usually insufficient to provide a constant stream, so tape drives were typically designed for start-stop operation. Early drives used very large spools, which necessarily had high inertia and did not start and stop moving easily. To provide high start, stop and seek performance, several feet of loose tape

4720-412: The partitioning feature that allows a tape to be divided into two separately writable areas, known as partitions. LTO-6 extends the specification to allow 4 separate partitions. The Linear Tape File System (LTFS) is a self-describing tape format and file system made possible by the partition feature. File data and filesystem metadata are stored in separate partitions on the tape. The metadata, which uses

4800-409: The predicted "death of tape". The presence of five certified media manufacturers and four certified mechanism manufacturers for a while produced a competitive market for LTO products. However, as of 2019, there are only two manufacturers developing media, Sony and Fuji, and only IBM is developing mechanisms. Tape drive A tape drive is a data storage device that reads and writes data on

4880-405: The raw capacity. The compression ratio actually achievable depends on the data being compressed. Some data has little redundancy; large video files, for example, already use compression and cannot be compressed further. A database with repetitive entries, on the other hand, may allow compression ratios better than 10:1. A disadvantageous effect termed shoe-shining occurs during read/write if

SECTION 60

#1733094088018

4960-633: The ridge the shingles on one side of the roof simply extend past the ridge or there is a ridge cap consisting of boards, copper, or lead sheeting. An asphalt shingle roof has flexible asphalt shingles as the ridge cap. Some roof shingles are non-combustible or have a better fire rating than others which influence their use, some building codes do not allow the use of shingles with less than a class-A fire rating to be used on some types of buildings. Due to increased fire hazard, wood shingles and organic-based asphalt shingles have become less common than fiberglass-based asphalt shingles. No shingles are water-tight so

5040-420: The same mid-range market segment. Much of the technology is an extension of the work done by IBM at its Tucson lab during the previous 20 years. In 2000, and around the time of the release of LTO-1, Seagate's magnetic tape division was spun off as Seagate Removable Storage Solutions, later renamed Certance , which was subsequently acquired by Quantum. Initial plans called for two distinct LTO formats: Despite

5120-411: The same player. The outer shell, made of plastic, sometimes with metal plates and parts, permits ease of handling of the fragile tape, making it far more convenient and robust than having spools of exposed tape. Simple analog cassette audio tape recorders were commonly used for data storage and distribution on home computers at a time when floppy disk drives were very expensive. The Commodore Datasette

5200-480: The slates. Slate shingles may be cut in a variety of decorative patterns and are available in several colors. Flagstone shingles are a traditional roofing material. Some stone shingles are fastened in place but some simply are held by gravity, so the roof pitch cannot be too steep or the stones will slide off the roof. Sandstone has also been used to make shingles. Fibre cement shingles are often known by their manufacturer's name, such as Eternit or Transite . Often,

5280-623: The tape lifespan. LTO uses an automatic verify-after-write technology to immediately check the data as it is being written, but some backup systems explicitly perform a completely separate tape reading operation to verify the tape was written correctly. This separate verify operation doubles the number of end-to-end passes for each scheduled backup, and reduces the tape life by half. The original release of LTO technology defined an optional data compression feature. Subsequent generations of LTO have introduced new technologies, including WORM, encryption, and partitioning features. These features are built into

5360-410: The tape medium in a WORM cartridge. The LTO-4 specification added a feature to allow LTO-4 drives to encrypt data before it is written to tape. All LTO-4 drives must be aware of encrypted tapes, but are not required to support the encryption process. All current LTO manufacturers support encryption natively enabled in the tape drives using Application Managed Encryption (AME). The algorithm used by LTO-4

5440-534: The tape speed level to the computer's data rate. Example speed levels could be 50 percent, 75 percent and 100 percent of full speed. A computer that streams data slower than the lowest speed level (e.g., at 49 percent) will still cause shoe-shining. Magnetic tape is commonly housed in a casing known as a cassette or cartridge —for example, the 4-track cartridge and the Compact Cassette . The cassette contains magnetic tape to provide different audio content using

5520-418: The tape. These drives have an average rewind time of 60 seconds and an average access time (from beginning of tape) of about 56 seconds. Because of serpentine writing methods, rewinding often takes less time than the maximum. If a tape is written to full capacity, there is no rewind time, since the last pass is a reverse pass leaving the head at the beginning of the tape (number of tracks ÷ tracks written per pass

5600-453: The top half of the shell is the normal color of that generation for that manufacturer, and the bottom half of the shell is a light gray. Every LTO cartridge has a cartridge memory chip inside it. It is made up of 511, 255, or 128 blocks of memory, where each block is 32 bytes for a total of 16 KiB for LTO-6 to 8; 8 KiB for LTO-4 and 5; and 4 KiB on LTO-1 to 3 and cleaning cartridges. This memory can be read or written, one block at

5680-492: The use of an internal data buffer to somewhat reduce start-stop situations. These drives are often referred to as tape streamers . The tape was stopped only when the buffer contained no data to be written , or when it was full of data during reading. As faster tape drives became available, despite being buffered, the drives started to suffer from the shoe-shining sequence of stop, rewind, start. Some newer drives have several speeds and implement algorithms that dynamically match

5760-497: The usual name outside the US. Slate roof shingles are relatively expensive to install but can last 80 to 400 years depending on the quality of the slate used, and how well they are maintained. The material itself deteriorates only slowly, and may be recycled from one building to another. The primary means of failure in a slate roof is when individual slates lose their peg attachment and begin to slide out of place. This can open up small gaps above each slate. A secondary mode of failure

5840-447: The volume of data that can be stored without manual intervention. In the early days of home computing , floppy and hard disk drives were very expensive. Many computers had an interface to store data via an audio tape recorder , typically on Compact Cassettes . Simple dedicated tape drives, such as the professional DECtape and the home ZX Microdrive and Rotronics Wafadrive , were also designed for inexpensive data storage. However,

5920-470: The whole tape is reformatted. In spite of these disadvantages, there are several use cases where LTFS-formatted tape is superior to disk and other data storage technologies. While LTO seek times can range from 10 to 100 seconds, the streaming data transfer rate can match or exceed disk data transfer rates. Additionally, LTO cartridges are easily transportable and the latest generation can hold more data than other removable data storage formats. The ability to copy

6000-400: The width and the location of the data bands. The gaps between the poles correspond to the servo tracks, which are not erased. Tapes erased by this equipment can be recorded again. Although keeping a tape drive clean is important, normal cleaning cartridges are abrasive and frequent use will shorten the drive's lifespan. LTO drives have an internal tape head cleaning brush that is activated when

6080-705: Was a dedicated data version using the same media. Elimination of the capstan and pinch-roller system Manufacturers often specify the capacity of tapes using data compression techniques; compressibility varies for different data (commonly 2:1 to 8:1), and the specified capacity may not be attained for some types of real data. As of 2014 , tape drives capable of higher capacity were still being developed. In 2011, Fujifilm and IBM announced that they had been able to record 29.5 billion bits per square inch with magnetic-tape media developed using Barium Ferrite (BaFe) particles and nanotechnologies, allowing drives with true (uncompressed) tape capacity of 35 TB. The technology

6160-553: Was designed to meet the demanding requirements of its mainframe products. DEC's CompacTape was targeted at a broader market, including minicomputers and smaller systems. Later on, it was renamed Digital Linear Tape (DLT) and eventually sold to Quantum Corporation . In the late 1980s, Exabyte's Data8 format, derived from Sony's dual-reel cartridge 8 mm video format, saw some popularity, especially with UNIX systems. Sony followed this success with their own now-discontinued 8 mm data format, Advanced Intelligent Tape (AIT). By

6240-404: Was not expected to be commercially available for at least a decade. In 2014, Sony and IBM announced that they had been able to record 148 billion bits per square inch with magnetic tape media developed using a new vacuum thin-film forming technology able to form extremely fine crystal particles, allowing true tape capacity of 185 TB. On December 15, 2020, Fujifilm and IBM announced

6320-418: Was played out and pulled by a suction fan down into two deep open channels on either side of the tape head and capstans . The long thin loops of tape hanging in these vacuum columns had far less inertia than the two reels and could be rapidly started, stopped and repositioned. The large reels would move as required to keep the slack tape in the vacuum columns. Later, most tape drives of the 1980s introduced

6400-613: Was released in 2000 and stored 100  GB of data in a cartridge; throughout newer generations, the capacity has increased while maintaining the same physical size. They feature built-in encryption for safer storing and transporting of data, and the partition feature enables usage of LTFS , generally having higher capacity, better long-term stability, and lower unit cost than other data storage formats. There are also write once read many LTO cartridges, useful to protect against accidental or malicious deletion. Half-inch (12.65 mm) wide magnetic tape has been used for data storage since

#17982