IRIX Base Documentation 2002 November

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ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) NNNNAAAAMMMMEEEE tps, tpsc - SCSI tape interface SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS ////ddddeeeevvvv////rrrrmmmmtttt////ttttppppssss**** ////ddddeeeevvvv////rrrrmmmmtttt////****////lllluuuunnnn****////cccc****pppp**** DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN Silicon Graphics systems support the Small Computer System Interface (SCSI) for various tape drives, including QIC24 and QIC150 1/4" cartridges, 9-track, 8 mm video, Ampex DIS/DST series, DLT (digital linear tape), IBM 3590 and 3570, STK 9490 and 9840, STK SD3, Sony GY-10 and GY-2120, and DAT (digital audio tape) tape drives. Not all systems support all tape drives. Since so many different types of devices are supported, and not all their features can be determined directly from the drive, a configuration table defines their capabilities. This is usually found in the file /_v_a_r/_s_y_s_g_e_n/_m_a_s_t_e_r._d/_s_c_s_i. The special files are named according to this convention: PPPPaaaarrrraaaalllllllleeeellll SSSSCCCCSSSSIIII aaaannnndddd FFFFCCCC----AAAALLLL ////ddddeeeevvvv////{rrrr}mmmmtttt////ttttppppssss_c_o_n_t_r_o_l_l_e_rdddd_I_D{nnnnrrrr}{nnnnssss}{ssss}{vvvv}{...._d_e_n_s_i_t_y}{cccc} FFFFiiiibbbbrrrreeee CCCChhhhaaaannnnnnnneeeellll FFFFaaaabbbbrrrriiiicccc ////ddddeeeevvvv////{rrrr}mmmmtttt////_n_o_d_e_n_a_m_e////lllluuuunnnn_l_u_n{nnnnrrrr}{nnnnssss}{ssss}{vvvv}{...._d_e_n_s_i_t_y}{cccc}////cccc_c_o_n_t_r_o_l_l_e_rpppp_p_o_r_t Note that the Fabric device names always specify the _l_u_n, even if it is zero. _c_o_n_t_r_o_l_l_e_r is the SCSI controller number and _I_D is variously known as the SCSI ID, the SCSI address, the drive address, and the unit number. The _n_o_d_e_n_a_m_e and _p_o_r_t are used to indicate the Fibre Channel world wide name (WWN) and the device port number. A Fibre Channel Fabric device may have multiple special filenames. If the _n_o_d_e_n_a_m_e and _l_u_n of different filenames are the same, respectively, these filenames represent the same physical device. Care should be taken not to use the same device at the same time by unintentionally opening different filenames of the same device. The device types are: {nnnnrrrr} no-rewind on close device {nnnnssss} non-byte swapping device {ssss} byte swapping device {vvvv} variable block size device. This feature is present on most current generation tape drives, including those from STK, IBM, Sony, Quantum and others. PPPPaaaaggggeeee 1111 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) {ssssttttaaaatttt} a special purpose device; it can be used even when one of the other names for the same physical device is already opened (see below) {...._d_e_n_s_i_t_y} for 9-track tape it is one of 800, 1600, 3200, or 6250; for the Exabyte 8500 it is one of 8200 and 8500; for DLT7000 it is one of 4000 and 7000 {cccc} data compression is supported for Archive Python 01931 DDS-2 DAT, Sony SDT-9000 DDS-3 DAT, the various DLTs, IBM Magstar 3590 and IBM Magstar MP 3570, EXABYTE 8900, STK 9490 and 9840, STK SD3, Sony GY-2120, and Fujitsu M1016/M1017 3480 devices as shipped. Compression is not the same as density and should not be confused with density. The degree to which compression increases capacity is data dependent. These special devices are accessible by only one program at a time, except for the {ssssttttaaaatttt} device. Opens on the {ssssttttaaaatttt} device can block for several seconds, if another name for the same devices is being opened or closed at the same time. Similarly, the MTIOCGET ioctl on the {ssssttttaaaatttt} device can block if long operations are in progress via one of the other names for the same device. The only operation the {ssssttttaaaatttt} device supports is the MTIOCGET ioctl, open, and close; all other attempted operations cause the EINVAL errno to be returned. It never causes any tape movement of any kind (in particular, it never tries to load the tape, even if media is present). Typically, if this tape drive is used as the system tape drive, the device-specific names described above are linked to user-friendly names in the /_d_e_v directory. See NNNNOOOOTTTTEEEESSSS below and _m_t_i_o(7) for a description of the user-friendly names. SSSSPPPPEEEECCCCIIIIAAAALLLL FFFFEEEEAAAATTTTUUUURRRREEEESSSS The different devices support a multitude of capabilities. In particular, some support multiple densities, some support fixed block size only, many support variable block sizes, some support multiple speeds, some support direct transfer of audio data over the SCSI bus. Most of these features are selected by which minor device is opened, and PPPPaaaaggggeeee 2222 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) others must be set via ioctl commands. The list of capabilities that a particular drive supports is set by the MMMMTTTTCCCCAAAANNNN____**** bits set in the _m_a_s_t_e_r._d/_s_c_s_i file for that drive. When a capability required for an operation is not set, the EINVAL error code is returned for the request. In particular, in audio mode the variable block size device must always be used for I/O, and parameters such as the recording frequency, program number, and so on are all part of the data stream. Additionally, when in audio mode the rewind and seek commands return immediately. If the drive is closed in this state, subsequent opens block until they are completed. If the drive remains open, certain commands, such as MTIOCGET and MTIOCAUDPOSN, can be used to determine the current position of the tape during the seek or rewind operation; the third argument is a pointer to a struct mtaudio. The MTAUD tape op is used to enable and disable audio mode. The third argument is 0 to use data mode and 1 to use audio mode. Many of the features that require ioctls can be set or changed via the _m_t(1) command. The data structures and values for these ioctls can be found in the include file /_u_s_r/_i_n_c_l_u_d_e/_s_y_s/_m_t_i_o._h, which is shipped with all systems. There are extensive comments in this file, and at this time no attempt has been made to document most of them here or in the _m_t_i_o(7) reference page. However, there are a few surprising return values that are mentioned here. In particular, when using partitioned tapes (see mmmmtttt sssseeeettttppppaaaarrrrtttt, or the MTSETPART ioctl), partition 0 is the 'main' partition, which is the final part of the tape, and partition 1 is the partition closest to BOT. Partitioned tapes are intended primarily so that a tape directory can be written at the beginning of the tape, without any worry of overwriting the data portion of the tape. In addition, partitioned tapes indicate BOT (EOT) when at beginning (end) of partition, rather than the 'real' BOT (EOT). Some devices support overwrite at arbitrary tape positions, while others require that the tape be at BOT or EOD (end of data). Others allow overwrite at any filemark (that is, 8mm from the BOT side of any filemark). Some experimentation may be necessary to decide what your particular drive supports; all drives support at a minimum writing at both BOT and EOD, assuming the media isn't write protected. TTTTAAAAPPPPEEEE MMMMOOOOVVVVEEEEMMMMEEEENNNNTTTT CCCCRRRRIIIITTTTEEEERRRRIIIIAAAA The only time the driver ever moves a tape is when told to, with the exceptions listed below. A command that causes tape movement is always issued, assuming that it is a valid command and the media is loaded. A significant change from IRIX releases prior to 4.0 is that the driver does NOT automatically position to the next filemark on the first command that does I/O to the tape. This means that mmmmtttt bbbbssssrrrr, and mmmmtttt ffffssssrrrr now have meaning since the tape is in fact left where it is positioned. It is now the programmer's or user's responsibility to ensure that the tape is in a PPPPaaaaggggeeee 3333 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) valid state for I/O. The drive or driver still detects and prevents operations not valid for the current tape position, returning an appropriate error in _e_r_r_n_o. 1. If the first read after an open encounters a filemark before transferring any data and the tape was not known to be at the top of a filemark or BOT, the filemark is skipped and the read retried. Any further errors are reported exactly as they occur. In particular, if two sequential filemarks are found, the tape is positioned between them. 2. If a read command encounters a filemark, that read returns a short count (if any data was read) or 0. If a short count is returned, the next read returns 0, allowing detection of filemarks. An MTFSF ioctl should not be done at this point, as the tape drive itself has already passed over the filemark. If an MTFSF is done at this point, the count should be decremented by one. The driver attempts to deal with this case, but can not always do so, due to differences in drive firmware. The read following the read that returns 0 returns the data in the next tape file, if any. Note that this is a change from earlier IRIX releases, which required an explicit MTFSF or other tape ioctl to move the tape before further reads could be done. The new behavior is consistent with most actual tape drives and tape drivers in most BSD-derived UNIX systems. Similarly, if an MTFSR ioctl encounters a filemark, it stops at the filemark and subsequent reads return data from the next tapefile, if any. 3. If early warning is encountered on a write or write filemark, the driver does not allow further writes or write filemarks, unless the MTANSI ioctl is issued. Any data remaining is flushed to tape, if possible. For the QIC tape drives and the 8mm drives, an error is returned on both read and write unless all the data was transferred when early warning is encountered. This is so that older multi-volume backups continue to work and new ones can be read on older releases. All newer drives (9 track, DAT, and future drive types) return a short count if not all the data could be transferred. Requests other than read or write are sent to the tape drive as usual. 4. On close, if the last tape movement operation was a successful write (not a write filemark), the following happens: a) Half-inch tape drives write two filemarks and then backspace one file, so that the tape is positioned between the two filemarks just written. If, however, the tape is not in ansi mode and early warning has been encountered, no write filemark or backspace is done; filemarks are never written in audio mode. PPPPaaaaggggeeee 4444 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) b) Other tape drives write one filemark. No backspace is done. 5. On the first status request or request that does tape motion after a system boot, a SCSI bus reset, or a tape cartridge insertion, the tape is rewound and loaded; this occurs even for the norewind devices. [Note: This can be suppressed via master.d/scsi changes (e.g. Ampex drives)]. In addition, most drives rewind a tape when it is ejected. This means that if you wish to append a new dataset to a tape that already contains datasets, you should always issue the mmmmtttt ffffeeeeoooommmm command AFTER loading the tape, just prior to using the program that will append to the tape. Do not count on a tape remaining at EOD, just because that is where it was before it was removed. For devices that support it, the prevent media removal command is sent to the drive on open and released on close, so that eject buttons (when present) are disabled. EEEERRRRRRRROOOORRRR RRRREEEETTTTUUUURRRRNNNNSSSS The following errors are returned by this driver; other errors can also be returned by higher levels of the operating system. EAGAIN The drive returned an error indicating it was not ready (tape ejected, drive taken offline, and so on). EBUSY Returned on opens when the drive has already been opened. EFAULT A bad address was passed in a call that required a data transfer. EINVAL This is returned for requests that are invalid for one reason or another including: +o Attempting to write or write file-mark after reading (except in audio mode, for devices that support it) without an intervening close, or ioctl to re-position the tape. +o Attempting to read after writing (same exceptions as for writing). +o Using an invalid count on read, write, write file-mark, and so on. +o Attempting to do MTAFILE on a drive that doesn't support it (the MTCAN_APPEND bit is not set in the _m_a_s_t_e_r._d/_s_c_s_i file). +o Attempting to do an ioctl on a drive that doesn't support it (such as MTBSR on Cipher 540S) or attempting to do an unsupported MTOP operation or other unsupported ioctl's. PPPPaaaaggggeeee 5555 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) +o Attempting to write to a QIC24 cartridge from a QIC150 drive (an MTIOCGET should be done, and the *QIC* bits should be checked for in mt_dposn to confirm this error). +o Attempting to do something when not at BOT that can only be done at BOT, such as writing or reading a Kennedy tape drive at a different speed than was previously used or switching from the variable block size device to the fixed block size device. (In IRIX 4.0, an attempt to use a different density is allowed, but the drive continues to use the original density.) +o Attempting to perform reads, writes, or ioctls other than MTIOCGET on the {ssssttttaaaatttt} device. EIO A generic error occurred, such as a SCSI bus reset, unrecoverable media error, and so on. Also occurs on close or read/write if the media has been unloaded while the device is open. ENOMEM An attempt was made to read data with a count less than that at which the block was written. This can only happen with drives that support variable block sizes. It can also occur if the kernel memory allocator is not able to allocate memory for the driver structures, or the request exceeds maxdmasize for the system. ENOSPC Occurs on read or space commands that encounter end of tape or end of data, on writes that are attempted at end of tape, and also on some other commands that encounter EOT or EOD. EROFS A write or write file-mark was attempted to a write-protected tape. ENODEV An open was attempted on a device with an invalid SCSI controller or SCSI ID specified (that is, a mknod with the wrong arguments was used to create the device special file) or an attempt to open a tape in variable blocksize mode when the device doesn't support it. Also occurs when the SCSI inquiry command fails or returns indicating that the device is not a tape device (media not removable, or not a sequential access device). NNNNOOOOTTTTEEEESSSS High density tape cartridges such as the DC6150 (originally called 600 XTD) written on a system equipped with QIC 150 tape drives can NOT be read on older systems. Even if a low density tape (such as DC 600A) is used, it is still written at a higher density (QIC 120) than older tape drives can read. Tapes written on the older systems can still be read on the new tape drives, however. Systems with QIC 150 cartridge tape drives such as the Personal IRIS are able to read QIC24 tapes (310 oersted) such as the DC 300XL, but are not able to write them. PPPPaaaaggggeeee 6666 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) All tape devices other than the QIC (quarter-inch) tape drives have /_d_e_v/_t_a_p_e linked to the {nnnnssss} device for performance, since there is no compatibility issue, and byte swapping is done in software. Most newer drives support variable block size devices, and the /_d_e_v/_t_a_p_e link uses those by default; when multiple densities are supported, as with 9-track, the link is to the highest capacity device. For compatibility with earlier IRIX releases, the 8mm device is linked to the fixed block device. See the (unfortunately somewhat confusing) script /_d_e_v/_M_A_K_E_D_E_V for details; in particular, look at the ttttaaaappppeeeelllliiiinnnnkkkkssss target. Each time the tape drive is closed and the drive has reported recovered error, the driver reports to the console and (as normally configured) to /_v_a_r/_a_d_m/_S_Y_S_L_O_G the number of recovered errors, if any. A small number is not indicative of problems, but a large number (somewhere above about 2-5% errors as a percentage of I/Os, depending on media age and quality) probably indicates that the media is approaching the end of its lifetime, that the drive read/write heads are dirty, or that the heads need to be realigned. A typical recovered error message might look like: NOTICE: tps0d7 had 8 successfully retried commands (1% of r/w) The first number is the controller number, the second is the SCSI ID on that controller. It is important to realize that these are _r_e_c_o_v_e_r_e_d errors (at the drive level) and therefore do not result in errors being reported to the program doing the tape I/O. It should be noted that the reported percentage of retried errors for some devices, most notably EXABYTE, may be shown to be orders of magnitude larger than the actual number of I/Os. This is not necessarily indicative of a serious problem when one realizes how this value is derived. The EXABYTE 8505, for example, when returning the number of retried I/Os will report the number of retried 1Kbyte blocks, and hence an alarmingly large reported percentage of retried errors. With more recent versions of microcode, the Ampex DIS/DST series of drives support variable length blocks. These should be detected as such and the appropriate device names created. It is important to note that even though variable blocks are supported, blocks smaller than 1,199,840 bytes will reduce cartridge capacity and throughput. Nine track tape users wishing to read large blocks (i.e. "gapless") tapes should obtain their drive from the M4 Data Corporation in Florida. They should request the "SGI Long Block" feature to insure that the proper microcode is installed in the 9914 drive. These drives will identify themselves as "SGI" for the vendor and "GOLD SEAL" for the model. The default master.d/scsi supplied by SGI includes a definition for this drive. It is also important to check that maxdmasize is set correctly for the system. PPPPaaaaggggeeee 7777 ttttppppssss((((7777MMMM)))) ttttppppssss((((7777MMMM)))) FFFFIIIILLLLEEEESSSS /dev/rmt/tps* /dev/rmt/*/lun*/c*p* /dev/mt exists as a symlink to /_d_e_v/_r_m_t; the use of the /_d_e_v/_m_t pathname is deprecated and is supported only for compatibility /dev/tape, /dev/nrtape, /dev/tapens, /dev/nrtapens convenience links to the "preferred" device in /_d_e_v/_r_m_t (highest SCSI ID on lowest numbered SCSI bus, for tps devices only) /var/sysgen/master.d/scsi contains a configuration table indicating what devices support what features and what string should be matched against the string returned by the SCSI inquiry command and the _h_i_n_v(1M) command; this was formerly in _m_a_s_t_e_r._d/_t_p_s_c /dev/MAKEDEV a makefile (normally invoked by the superuser in the /_d_e_v directory only) that creates devices that match the installed tape drives if invoked as ccccdddd ////ddddeeeevvvv;;;; ....////MMMMAAAAKKKKEEEEDDDDEEEEVVVV ttttaaaappppeeee SSSSEEEEEEEE AAAALLLLSSSSOOOO MAKEDEV(1M), bru(1), cpio(1), hinv(1M), mt(1), tar(1), ioctl(2), rmtops(3), datframe(4), mtio(7). PPPPaaaaggggeeee 8888