From owner-freebsd-doc@FreeBSD.ORG Sat Jan 12 02:20:01 2013 Return-Path: Delivered-To: freebsd-doc@smarthost.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 1E72739A for ; Sat, 12 Jan 2013 02:20:01 +0000 (UTC) (envelope-from gnats@FreeBSD.org) Received: from freefall.freebsd.org (freefall.freebsd.org [IPv6:2001:1900:2254:206c::16:87]) by mx1.freebsd.org (Postfix) with ESMTP id 06181EFF for ; Sat, 12 Jan 2013 02:20:01 +0000 (UTC) Received: from freefall.freebsd.org (localhost [127.0.0.1]) by freefall.freebsd.org (8.14.6/8.14.6) with ESMTP id r0C2K09j035822 for ; Sat, 12 Jan 2013 02:20:00 GMT (envelope-from gnats@freefall.freebsd.org) Received: (from gnats@localhost) by freefall.freebsd.org (8.14.6/8.14.6/Submit) id r0C2K0rk035818; Sat, 12 Jan 2013 02:20:00 GMT (envelope-from gnats) Resent-Date: Sat, 12 Jan 2013 02:20:00 GMT Resent-Message-Id: <201301120220.r0C2K0rk035818@freefall.freebsd.org> Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer) Resent-To: freebsd-doc@FreeBSD.org Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org, Diane Bruce Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 66FD52BB for ; Sat, 12 Jan 2013 02:15:35 +0000 (UTC) (envelope-from db@db.net) Received: from diana.db.net (diana.db.net [66.113.102.10]) by mx1.freebsd.org (Postfix) with ESMTP id 4898EECE for ; Sat, 12 Jan 2013 02:15:35 +0000 (UTC) Received: from night.db.net (localhost [127.0.0.1]) by diana.db.net (Postfix) with ESMTP id A48692AA4C0 for ; Fri, 11 Jan 2013 19:15:26 -0700 (MST) Received: by night.db.net (Postfix, from userid 1000) id E120C1CCDF; Fri, 11 Jan 2013 21:14:35 -0500 (EST) Message-Id: <20130112021435.E120C1CCDF@night.db.net> Date: Fri, 11 Jan 2013 21:14:35 -0500 (EST) From: Diane Bruce To: FreeBSD-gnats-submit@freebsd.org X-Send-Pr-Version: 3.113 Subject: docs/175226: obsolete section on tapes in handbook X-BeenThere: freebsd-doc@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: Diane Bruce List-Id: Documentation project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 12 Jan 2013 02:20:01 -0000 >Number: 175226 >Category: docs >Synopsis: obsolete section on tapes in handbook >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-doc >State: open >Quarter: >Keywords: >Date-Required: >Class: doc-bug >Submitter-Id: current-users >Arrival-Date: Sat Jan 12 02:20:00 UTC 2013 >Closed-Date: >Last-Modified: >Originator: Diane Bruce >Release: FreeBSD 9.0-RELEASE amd64 >Organization: Do I have to have any? >Environment: System: FreeBSD night.db.net 9.0-RELEASE FreeBSD 9.0-RELEASE #11: Sat Jun 30 08:32:31 EST 2012 root@night.db.net:/usr/obj/usr/src/sys/GENERIC amd64 >Description: >How-To-Repeat: >Fix: Index: en_US.ISO8859-1/books/handbook/disks/chapter.xml =================================================================== --- en_US.ISO8859-1/books/handbook/disks/chapter.xml (revision 40568) +++ en_US.ISO8859-1/books/handbook/disks/chapter.xml (working copy) @@ -2085,234 +2085,77 @@ tape media - The major tape media are the 4mm, 8mm, QIC, mini-cartridge - and DLT. + Tape technology has continued to evolve but is less likely to be + used in a modern system. Modern backup systems tend to use offsite + combined with local removable disk drive technologies. Nevertheless + FreeBSD will support any tape drive that uses SCSI such as LTO and + older devices such as DAT. There is limited support for SATA/USB tape + as well. + - - 4mm (DDS: Digital Data Storage) + + Tape drives/serial access - tape media - DDS (4mm) tapes + tape drives - - tape media - QIC tapes - - 4mm tapes are replacing QIC as the workstation backup - media of choice. This trend accelerated greatly when Conner - purchased Archive, a leading manufacturer of QIC drives, and - then stopped production of QIC drives. 4mm drives are small - and quiet but do not have the reputation for reliability that - is enjoyed by 8mm drives. The cartridges are less expensive - and smaller (3 x 2 x 0.5 inches, 76 x 51 x 12 mm) than 8mm - cartridges. 4mm, like 8mm, has comparatively short head life - for the same reason, both use helical scan. - Data throughput on these drives starts ~150 kB/s, - peaking at ~500 kB/s. Data capacity starts at - 1.3 GB and ends at 2.0 GB. Hardware compression, - available with most of these drives, approximately doubles the - capacity. Multi-drive tape library units can have 6 drives in - a single cabinet with automatic tape changing. Library - capacities reach 240 GB. - - The DDS-3 standard now supports tape capacities up to - 12 GB (or 24 GB compressed). - - 4mm drives, like 8mm drives, use helical-scan. All the - benefits and drawbacks of helical-scan apply to both 4mm and - 8mm drives. - - Tapes should be retired from use after 2,000 passes or 100 - full backups. + FreeBSD uses the sa(4) driver, providing /dev/sa0, + /dev/nsa0 and /dev/esa0. + In normal use only /dev/sa0 is needed. + /dev/nsa0 is the same + physical drive as /dev/sa0 but does + not rewind the tape when a file is written to the tape and + this enables more than one backup to be done on a tape. + /dev/esa0 Ejects the tape after + a close if applicable. + - - 8mm (Exabyte) + + Using mt(1) to control the tape drive tape media - Exabyte (8mm) tapes + mt - 8mm tapes are the most common SCSI tape drives; they are - the best choice of exchanging tapes. Nearly every site has an - Exabyte 2 GB 8mm tape drive. 8mm drives are reliable, - convenient and quiet. Cartridges are inexpensive and small - (4.8 x 3.3 x 0.6 inches; 122 x 84 x 15 mm). One downside of - 8mm tape is relatively short head and tape life due to the - high rate of relative motion of the tape across the - heads. - - Data throughput ranges from ~250 kB/s to - ~500 kB/s. Data sizes start at 300 MB and go up to - 7 GB. Hardware compression, available with most of these - drives, approximately doubles the capacity. These drives are - available as single units or multi-drive tape libraries with 6 - drives and 120 tapes in a single cabinet. Tapes are changed - automatically by the unit. Library capacities reach - 840+ GB. - - The Exabyte Mammoth model supports - 12 GB on one tape (24 GB with compression) and costs - approximately twice as much as conventional tape - drives. - - Data is recorded onto the tape using helical-scan, the - heads are positioned at an angle to the media (approximately 6 - degrees). The tape wraps around 270 degrees of the spool that - holds the heads. The spool spins while the tape slides over - the spool. The result is a high density of data and closely - packed tracks that angle across the tape from one edge to the - other. + mt(1) is the FreeBSD utility for controlling other operations + of the tape drive such as seeking through files on a tape or writing + tape control marks to the tape. + + For example you have already written several backups to the tape + and you wish to save the first 3 backups without overwriting them. + mt -f /dev/nsa0 fsf 3 + - - QIC + + Using tar(1) to read/write backups on tape - - tape media - QIC-150 - - - QIC-150 tapes and drives are, perhaps, the most common - tape drive and media around. QIC tape drives are the least - expensive serious backup drives. The downside - is the cost of media. QIC tapes are expensive compared to 8mm - or 4mm tapes, up to 5 times the price per GB data storage. - But, if your needs can be satisfied with a half-dozen tapes, - QIC may be the correct choice. QIC is the - most common tape drive. Every site has a - QIC drive of some density or another. Therein lies the rub, - QIC has a large number of densities on physically similar - (sometimes identical) tapes. QIC drives are not quiet. These - drives audibly seek before they begin to record data and are - clearly audible whenever reading, writing or seeking. QIC - tapes measure 6 x 4 x 0.7 inches (152 x - 102 x 17 mm). - - Data throughput ranges from ~150 kB/s to - ~500 kB/s. Data capacity ranges from 40 MB to - 15 GB. Hardware compression is available on many of the - newer QIC drives. QIC drives are less frequently installed; - they are being supplanted by DAT drives. - - Data is recorded onto the tape in tracks. The tracks run - along the long axis of the tape media from one end to the - other. The number of tracks, and therefore the width of a - track, varies with the tape's capacity. Most if not all newer - drives provide backward-compatibility at least for reading - (but often also for writing). QIC has a good reputation - regarding the safety of the data (the mechanics are simpler - and more robust than for helical scan drives). - - Tapes should be retired from use after 5,000 - backups. + An example of a simple backup using tar(1) and a tape drive. + tar cv file + As the default tape drive is /dev/sa0 + there is no need to specify it. + To specify a specific tape deivce from the command line. + tar cvf /dev/sa1dir + + Typical use to recover files backed up with tar from a tape. + tar xvf /dev/sa0 + - - - DLT - - - tape media - DLT - - - DLT has the fastest data transfer rate of all the drive - types listed here. The 1/2" (12.5mm) tape is contained in a - single spool cartridge (4 x 4 x 1 inches; 100 x 100 x 25 mm). - The cartridge has a swinging gate along one entire side of the - cartridge. The drive mechanism opens this gate to extract the - tape leader. The tape leader has an oval hole in it which the - drive uses to hook the tape. The take-up spool - is located inside the tape drive. All the other tape - cartridges listed here (9 track tapes are the only exception) - have both the supply and take-up spools located inside the - tape cartridge itself. - - Data throughput is approximately 1.5 MB/s, three - times the throughput of 4mm, 8mm, or QIC tape drives. Data - capacities range from 10 GB to 20 GB for a single - drive. Drives are available in both multi-tape changers and - multi-tape, multi-drive tape libraries containing from 5 to - 900 tapes over 1 to 20 drives, providing from 50 GB to - 9 TB of storage. - - With compression, DLT Type IV format supports up to - 70 GB capacity. - - Data is recorded onto the tape in tracks parallel to the - direction of travel (just like QIC tapes). Two tracks are - written at once. Read/write head lifetimes are relatively - long; once the tape stops moving, there is no relative motion - between the heads and the tape. - - + - AIT + Using restore(8)/dump(8) to read/write backups on tape - - tape media - AIT - - - AIT is a new format from Sony, and can hold up to - 50 GB (with compression) per tape. The tapes contain - memory chips which retain an index of the tape's contents. - This index can be rapidly read by the tape drive to determine - the position of files on the tape, instead of the several - minutes that would be required for other tapes. Software such - as SAMS:Alexandria can operate - forty or more AIT tape libraries, communicating directly with - the tape's memory chip to display the contents on screen, - determine what files were backed up to which tape, locate the - correct tape, load it, and restore the data from the - tape. - - Libraries like this cost in the region of $20,000, pricing - them a little out of the hobbyist market. + An example of a simple backup using dump(8) and a tape drive. + dump -0u -f /dev/nsa0 /usr + + Typical use to recover files backed up with dump(8) from a tape. + restore -f /dev/nsa0 + - - Using a New Tape for the First Time - - The first time that you try to read or write a new, - completely blank tape, the operation will fail. The console - messages should be similar to: - - sa0(ncr1:4:0): NOT READY asc:4,1 -sa0(ncr1:4:0): Logical unit is in process of becoming ready - - The tape does not contain an Identifier Block (block - number 0). All QIC tape drives since the adoption of QIC-525 - standard write an Identifier Block to the tape. There are two - solutions: - - - - mt fsf 1 causes the tape drive to - write an Identifier Block to the tape. - - - - Use the front panel button to eject the tape. - - Re-insert the tape and dump data to - the tape. - - dump will report - DUMP: End of tape detected and the - console will show: HARDWARE FAILURE info:280 - asc:80,96. - - rewind the tape using: - mt rewind. - - Subsequent tape operations are successful. - - - >Release-Note: >Audit-Trail: >Unformatted: