diff --git a/en_US.ISO8859-1/books/handbook/backups/Makefile b/en_US.ISO8859-1/books/handbook/backups/Makefile deleted file mode 100644 index 0ef5e26b26..0000000000 --- a/en_US.ISO8859-1/books/handbook/backups/Makefile +++ /dev/null @@ -1,15 +0,0 @@ -# -# Build the Handbook with just the content from this chapter. -# -# $FreeBSD$ -# - -CHAPTERS= backups/chapter.sgml - -VPATH= .. - -MASTERDOC= ${.CURDIR}/../${DOC}.${DOCBOOKSUFFIX} - -DOC_PREFIX?= ${.CURDIR}/../../../.. - -.include "../Makefile" diff --git a/en_US.ISO8859-1/books/handbook/backups/chapter.sgml b/en_US.ISO8859-1/books/handbook/backups/chapter.sgml deleted file mode 100644 index e66ab1f167..0000000000 --- a/en_US.ISO8859-1/books/handbook/backups/chapter.sgml +++ /dev/null @@ -1,861 +0,0 @@ - - - - Backups - - - Synopsis - - The following chapter will cover methods of backing up data, and - the programs used to create those backups. - - - - Tape Media - - tape media - The major tape media are the 4mm, 8mm, QIC, mini-cartridge and - DLT. - - - 4mm (DDS: Digital Data Storage) - - - tape media - DDS (4mm) tapes - - - 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 ~150kB/s, peaking at ~500kB/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. - - - - 8mm (Exabyte) - - tape media - Exabyte (8mm) tapes - - - 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 ~250kB/s to ~500kB/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. - - - - QIC - - 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; 15.2 x - 10.2 x 1.7 mm). Mini-cartridges, which - also use 1/4" wide tape are discussed separately. Tape libraries and - changers are not available. - - Data throughput ranges from ~150kB/s to ~500kB/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. - - - - XXX* Mini-Cartridge - - - - - - 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 1.5MB/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 - - 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. - - - - 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. - - - - - Backup Programs - backup software - - The three major programs are - &man.dump.8;, - &man.tar.1;, - and - &man.cpio.1;. - - - Dump and Restore - - backup software - dump / restore - - dump - restore - - The traditional Unix backup programs are - dump and restore. They - operate on the drive as a collection of disk blocks, below the - abstractions of files, links and directories that are created by - the filesystems. dump backs up an entire - filesystem on a device. It is unable to backup only part of a - filesystem or a directory tree that spans more than one - filesystem. dump does not write files and - directories to tape, but rather writes the raw data blocks that - comprise files and directories. - - If you use dump on your root directory, you - would not back up /home, - /usr or many other directories since - these are typically mount points for other filesystems or - symbolic links into those filesystems. - - dumphas quirks that remain from its early days in - Version 6 of AT&T Unix (circa 1975). The default - parameters are suitable for 9-track tapes (6250 bpi), not the - high-density media available today (up to 62,182 ftpi). These - defaults must be overridden on the command line to utilize the - capacity of current tape drives. - - rhosts - It is also possible to backup data across the network to a - tape drive attached to another computer with rdump and - rrestore. Both programs rely upon rcmd and - ruserok to access the remote tape drive. Therefore, - the user performing the backup must have - rhosts access to the remote computer. The - arguments to rdump and rrestore must be suitable - to use on the remote computer. (e.g. When - rdumping from a FreeBSD computer to an - Exabyte tape drive connected to a Sun called - komodo, use: /sbin/rdump 0dsbfu - 54000 13000 126 komodo:/dev/nrsa8 /dev/rda0a - 2>&1) Beware: there are security implications to - allowing rhosts commands. Evaluate your - situation carefully. - - It is also possible to use rdump and - rrestore in a more secure fashion over - ssh. - - - Using <command>rdump</command> over <application>ssh</application> - - &prompt.root; /sbin/dump -0uan -f - /usr | gzip -2 | ssh1 -c blowfish \ - targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz - - - - - - <command>tar</command> - - backup software - tar - - - &man.tar.1; also dates back to Version 6 of AT&T Unix - (circa 1975). tar operates in cooperation - with the filesystem; tar writes files and - directories to tape. tar does not support the - full range of options that are available from &man.cpio.1;, but - tar does not require the unusual command - pipeline that cpio uses. - - tar - Most versions of tar do not support - backups across the network. The GNU version of - tar, which FreeBSD utilizes, supports remote - devices using the same syntax as rdump. To - tar to an Exabyte tape drive connected to a - Sun called komodo, use: /usr/bin/tar - cf komodo:/dev/nrsa8 . 2>&1. For versions without - remote device support, you can use a pipeline and - rsh to send the data to a remote tape - drive. - - &prompt.root; tar cf - . | rsh hostname dd of=tape-device obs=20b - - If you are worried about the security of backing up over a - network you should use the ssh command - instead of rsh. - - - - <command>cpio</command> - - backup software - cpio - - - &man.cpio.1; is the original Unix file interchange tape - program for magnetic media. cpio has options - (among many others) to perform byte-swapping, write a number of - different archive formats, and pipe the data to other programs. - This last feature makes cpio and excellent - choice for installation media. cpio does not - know how to walk the directory tree and a list of files must be - provided through stdin. - cpio - - cpio does not support backups across - the network. You can use a pipeline and rsh - to send the data to a remote tape drive. - - &prompt.root; for f in directory_list; do -find $f >> backup.list -done -&prompt.root; cpio -v -o --format=newc < backup.list | ssh user@host "cat > backup_device - - Where directory_list is the list of - directories you want to back up, - user@host is the - user/hostname combination that will be performing the backups, and - backup_device is where the backups should - be written to (e.g., /dev/nrsa0). - - - - <command>pax</command> - - backup software - pax - - pax - POSIX - IEEE - - &man.pax.1; is IEEE/POSIX's answer to - tar and cpio. Over the - years the various versions of tar and - cpio have gotten slightly incompatible. So - rather than fight it out to fully standardize them, POSIX - created a new archive utility. pax attempts - to read and write many of the various cpio - and tar formats, plus new formats of its own. - Its command set more resembles cpio than - tar. - - - - <application>Amanda</application> - - backup software - Amanda - - Amanda - - - Amanda (Advanced Maryland - Network Disk Archiver) is a client/server backup system, - rather than a single program. An Amanda server will backup to - a single tape drive any number of computers that have Amanda - clients and a network connection to the Amanda server. A - common problem at sites with a number of large disks is - that the length of time required to backup to data directly to tape - exceeds the amount of time available for the task. Amanda - solves this problem. Amanda can use a "holding disk" to - backup several filesystems at the same time. Amanda creates - "archive sets": a group of tapes used over a period of time to - create full backups of all the filesystems listed in Amanda's - configuration file. The "archive set" also contains nightly - incremental (or differential) backups of all the filesystems. - Restoring a damaged filesystem requires the most recent full - backup and the incremental backups. - - The configuration file provides fine control of backups and the - network traffic that Amanda generates. Amanda will use any of the - above backup programs to write the data to tape. Amanda is available - as either a port or a package, it is not installed by default. - - - - Do Nothing - - Do nothing is not a computer program, but it is the - most widely used backup strategy. There are no initial costs. There - is no backup schedule to follow. Just say no. If something happens - to your data, grin and bear it! - - If your time and your data is worth little to nothing, then - Do nothing is the most suitable backup program for your - computer. But beware, Unix is a useful tool, you may find that within - six months you have a collection of files that are valuable to - you. - - Do nothing is the correct backup method for - /usr/obj and other directory trees that can be - exactly recreated by your computer. Some examples are the files that - comprise the HTML or PostScript version of this Handbook. - These document formats have been created from SGML input - files. Creating backups of the HTML or PostScript files is - not necessary. The SGML files are backed up regularly. - - - - Which Backup Program Is Best? - - LISA - - - &man.dump.8; Period. Elizabeth D. Zwicky - torture tested all the backup programs discussed here. The clear - choice for preserving all your data and all the peculiarities of Unix - filesystems is dump. Elizabeth created filesystems containing - a large variety of unusual conditions (and some not so unusual ones) - and tested each program by doing a backup and restore of those - filesystems. The peculiarities included: files with holes, files with - holes and a block of nulls, files with funny characters in their - names, unreadable and unwritable files, devices, files that change - size during the backup, files that are created/deleted during the - backup and more. She presented the results at LISA V in Oct. 1991. - See torture-testing - Backup and Archive Programs. - - - - Emergency Restore Procedure - - - Before the Disaster - - There are only four steps that you need to perform in - preparation for any disaster that may occur. - - disklabel - - - First, print the disklabel from each of your disks - (e.g. disklabel da0 | lpr), your filesystem table - (/etc/fstab) and all boot messages, - two copies of - each. - - fix-it floppies - Second, determine that the boot and fix-it floppies - (boot.flp and fixit.flp) - have all your devices. The easiest way to check is to reboot your - machine with the boot floppy in the floppy drive and check the boot - messages. If all your devices are listed and functional, skip on to - step three. - - Otherwise, you have to create two custom bootable - floppies which have a kernel that can mount all of your disks - and access your tape drive. These floppies must contain: - fdisk, disklabel, - newfs, mount, and - whichever backup program you use. These programs must be - statically linked. If you use dump, the - floppy must contain restore. - - Third, create backup tapes regularly. Any changes that you make - after your last backup may be irretrievably lost. Write-protect the - backup tapes. - - Fourth, test the floppies (either boot.flp - and fixit.flp or the two custom bootable - floppies you made in step two.) and backup tapes. Make notes of the - procedure. Store these notes with the bootable floppy, the - printouts and the backup tapes. You will be so distraught when - restoring that the notes may prevent you from destroying your backup - tapes (How? In place of tar xvf /dev/rsa0, you - might accidentally type tar cvf /dev/rsa0 and - over-write your backup tape). - - For an added measure of security, make bootable floppies and two - backup tapes each time. Store one of each at a remote location. A - remote location is NOT the basement of the same office building. A - number of firms in the World Trade Center learned this lesson the - hard way. A remote location should be physically separated from - your computers and disk drives by a significant distance. - - - A Script for Creating a Bootable Floppy - - /mnt/sbin/init -gzip -c -best /sbin/fsck > /mnt/sbin/fsck -gzip -c -best /sbin/mount > /mnt/sbin/mount -gzip -c -best /sbin/halt > /mnt/sbin/halt -gzip -c -best /sbin/restore > /mnt/sbin/restore - -gzip -c -best /bin/sh > /mnt/bin/sh -gzip -c -best /bin/sync > /mnt/bin/sync - -cp /root/.profile /mnt/root - -cp -f /dev/MAKEDEV /mnt/dev -chmod 755 /mnt/dev/MAKEDEV - -chmod 500 /mnt/sbin/init -chmod 555 /mnt/sbin/fsck /mnt/sbin/mount /mnt/sbin/halt -chmod 555 /mnt/bin/sh /mnt/bin/sync -chmod 6555 /mnt/sbin/restore - -# -# create the devices nodes -# -cd /mnt/dev -./MAKEDEV std -./MAKEDEV da0 -./MAKEDEV da1 -./MAKEDEV da2 -./MAKEDEV sa0 -./MAKEDEV pty0 -cd / - -# -# create minimum filesystem table -# -cat > /mnt/etc/fstab < /mnt/etc/passwd < /mnt/etc/master.passwd < - - - - - - - After the Disaster - - The key question is: did your hardware survive? You have been - doing regular backups so there is no need to worry about the - software. - - If the hardware has been damaged. First, replace those parts - that have been damaged. - - If your hardware is okay, check your floppies. If you are using - a custom boot floppy, boot single-user (type -s - at the boot: prompt). Skip the following - paragraph. - - If you are using the boot.flp and - fixit.flp floppies, keep reading. Insert the - boot.flp floppy in the first floppy drive and - boot the computer. The original install menu will be displayed on - the screen. Select the Fixit--Repair mode with CDROM or - floppy. option. Insert the - fixit.flp when prompted. - restore and the other programs that you need are - located in /mnt2/stand. - - Recover each filesystem separately. - - - mount - - root partition - - disklabel - - - newfs - - Try to mount (e.g. mount /dev/da0a - /mnt) the root partition of your first disk. If the - disklabel was damaged, use disklabel to re-partition and - label the disk to match the label that you printed and saved. Use - newfs to re-create the filesystems. Re-mount the root - partition of the floppy read-write (mount -u -o rw - /mnt). Use your backup program and backup tapes to - recover the data for this filesystem (e.g. restore vrf - /dev/sa0). Unmount the filesystem (e.g. umount - /mnt) Repeat for each filesystem that was - damaged. - - Once your system is running, backup your data onto new tapes. - Whatever caused the crash or data loss may strike again. Another - hour spent now may save you from further distress later. - - - - * I did not prepare for the Disaster, What Now? - - - -]]> - - - - - - What About Backups to Floppies? - - - Can I Use floppies for Backing Up My Data? - backup floppies - floppy disks - - Floppy disks are not really a suitable media for - making backups as: - - - - The media is unreliable, especially over long periods of - time - - - - Backing up and restoring is very slow - - - - They have a very limited capacity (the days of backing up - an entire hard disk onto a dozen or so floppies has long since - passed). - - - - However, if you have no other method of backing up your data then - floppy disks are better than no backup at all. - - If you do have to use floppy disks then ensure that you use good - quality ones. Floppies that have been lying around the office for a - couple of years are a bad choice. Ideally use new ones from a - reputable manufacturer. - - - - So How Do I Backup My Data to Floppies? - - The best way to backup to floppy disk is to use - tar with the (multi - volume) option, which allows backups to span multiple - floppies. - - To backup all the files in the current directory and sub-directory - use this (as root): - - &prompt.root; tar Mcvf /dev/fd0 * - - When the first floppy is full tar will prompt you to - insert the next volume (because tar is media independent it - refers to volumes. In this context it means floppy disk) - - Prepare volume #2 for /dev/fd0 and hit return: - - This is repeated (with the volume number incrementing) until all - the specified files have been archived. - - - - Can I Compress My Backups? - - tar - - - gzip - - compression - - Unfortunately, tar will not allow the - option to be used for multi-volume archives. - You could, of course, gzip all the files, - tar them to the floppies, then - gunzip the files again! - - - - How Do I Restore My Backups? - - To restore the entire archive use: - - &prompt.root; tar Mxvf /dev/fd0 - - There are two ways that you can use to restore only - specific files. First, you can start with the first floppy - and use: - - &prompt.root; tar Mxvf /dev/fd0 filename - - tar will prompt you to insert subsequent floppies until it - finds the required file. - - Alternatively, if you know which floppy the file is on then you - can simply insert that floppy and use the same command as above. Note - that if the first file on the floppy is a continuation from the - previous one then tar will warn you that it cannot - restore it, even if you have not asked it to! - - - - -