dump(1M)
dump, rdump - incremental filesystem backup for EFS filesystems
As shipped in IRIX 6.5.22. Last changed in IRIX 6.5.15.
NAME dump, rdump - incremental filesystem backup for EFS filesystems SYNOPSIS dump [ key [ argument ... ] ] filesystem rdump [ key [ argument ... ] ] filesystem DESCRIPTION dump and rdump are applicable only to EFS filesystems, use xfsdump(1m) for XFS filesystems. dump backs up all files in filesystem or files changed after a certain date to magnetic tape or files. The key specifies the date and other options about the dump. key consists of characters from the set 0123456789fusCcdbWwn. Any arguments supplied for specific options are given as subsequent words on the command line, in the same order as that of the options listed. If no key is given, the key is assumed to be 9u and the filesystem specified is dumped to the default tape device /dev/tape. 0-9 This number is the dump level. All files modified since the last date stored in the file /etc/dumpdates for the same filesystem at lesser levels are dumped. If no date is determined by the level, the beginning of time is assumed; thus the option 0 causes the entire filesystem to be dumped. For instance, if you did a level 2 dump on Monday, followed by a level 4 dump on Tuesday, a subsequent level 3 dump on Wednesday would contain all files modified or added to the filesystem since the level 2 (Monday) backup. A level 0 dump copies the entire filesystem to the dump volume. f Place the dump on the next argument file instead of the default tape device /dev/tape. If the name of the file is ``-'', dump writes to standard output. If the name of the file is of the format machine:device, the filesystem is dumped across the network to the remote machine. Since dump is normally run by root, the name of the local machine must appear in the .rhosts file of the remote machine. If the filename argument is of the form user@machine:device, dump attempts to execute as the specified user on the remote machine. The specified user must have a .rhosts file on the remote machine that allows root from the local machine. dump creates a remote server, /etc/rmt, on the client machine to access the tape device. u If the dump completes successfully, write the date of the beginning of the dump on file /etc/dumpdates. This file records a separate date for each filesystem and each dump level. The format of /etc/dumpdates is readable by people, consisting of one free format record per line: filesystem name, increment level, and ctime(3C) format dump date. /etc/dumpdates can be edited to change any of the fields, if necessary. s The size of the dump tape is specified in feet. The number of feet is taken from the next argument. It is recommended that the C option be used instead, as it is more predictable. When the specified size is reached, dump prompts the operator and wait for the reel/volume to be changed. d The density of the tape, expressed in BPI (bytes per inch), is taken from the next argument. This is used in calculating the amount of tape used per reel. It is recommended that the C option be used instead, as it is more predictable. b The blocking factor (number of 1-kilobyte blocks written out together) is taken from the next argument. The default is 10. The default blocking factor for tapes of density 6250 BPI and greater is 32. For some network, tape type, and server combinations, there may be a significant throughput improvement by using a blocking factor of 32, rather than the default of 10, when using rdump. If values larger than 32 are used, restore does not correctly determine the block size unless the b option is also used. To maximize tape utilization, use a blocking factor that is a multiple of 8. For most types of supported tape drives, the greatest capacity and tape throughput is obtained using a blocking factor of 128 or even larger; note that restore(1M) automatically determines the blocking factor only if it is 32 or less. C This specifies the total tape capacity in 1-kilobyte blocks, overriding the c, s, and d arguments if they are also given. Unlike the size and density arguments, the capacity is used as specified, no correction factors are applied. Since capacity lost to retries or underruns (by the drive), are not taken into account, you should be conservative when specifying capacity. The argument is parsed with strtoul(3C), so it can be in any base (for example, a 0x prefix specifies a hexadecimal value, a 0 prefix specifies octal, no prefix is decimal). The argument can have a k, K, m, or M suffix. The first two multiply the value by 1024, the third and fourth multiply by 1048576, so a tape with a 2.2 Gbyte capacity might be specified as C 2m allowing 10% loss to retries, and so on. When the specified capacity has been written, dump prompts the operator and wait for the reel/volume to be changed. It is not currently possible to specify different capacities for different volumes of multi-volume backups. c Indicates that the tape is a cartridge tape instead of the standard default half-inch reel. This should always be specified when using cartridge tapes, unless the C option is used. The values for blocking factor, size, and density are taken to be 10 (1-kilobyte blocks), 5400 feet, and 1000 BPI respectively unless overridden with the b, s, or d option. W dump tells the operator what filesystems need to be dumped. This information is gleaned from the files /etc/dumpdates and /etc/fstab. The W option causes dump to print out, for each filesystem in /etc/dumpdates, the most recent dump date and level and highlights those filesystems that should be dumped. The mnt_freq field in the /etc/fstab entry of the filesystem must be nonzero for dump to determine whether the filesystem should be dumped or not. If the W option is set, no other option must be given and dump exits immediately. w Is like W, but prints only those filesystems that need to be dumped. n Whenever dump requires operator attention, notify by means similar to a wall(1) all of the operators in the group operator. dump reads the character device associated with the filesystem and dumps the contents onto the specified tape device. It searches /etc/fstab to find the associated character device. NOTES rdump is a link to dump. Operator Intervention dump requires operator intervention on these conditions: end of tape, end of dump, tape write error, tape open error, or disk read error (if there are more than a threshold of 32). In addition to alerting all operators implied by the n key, dump interacts with the operator on dump's control terminal at times when dump can no longer proceed or if something is grossly wrong. All questions dump poses must be answered by typing yes or no, appropriately. Since making a dump involves a lot of time and effort for full dumps, dump checkpoints itself at the start of each tape volume. If writing that volume fails for some reason, dump, with operator permission, restarts itself from the checkpoint after the old tape has been rewound and removed and a new tape has been mounted. dump reports periodically, including usually the percentage of the dump completed, low estimates of the number of blocks to write in 1-kilobyte blocks (or, more strictly, TP_BSIZE units from protocols/dumprestore.h), the number of tapes it will take, the time to completion, and the time to the tape change. The estimated time is given as hours:minutes and is based on the time taken to dump the blocks already on tape. It is normal for this estimate to show variance, and the estimate improves over time. The output is verbose, so that others know that the terminal controlling dump is busy and will be for some time. Suggested Dump Schedule It is vital to perform full level 0 dumps at regular intervals. When performing a full dump, bring the machine down to single-user mode using shutdown -is. Otherwise the dump may not be internally consistent and may not restore correctly. While preparing for a full dump, it is a good idea to clean the tape drive and heads (most types of drives require head cleaning for approximately every 30 hours of tape motion). Incremental dumps allow for convenient backup and recovery of active files on a more frequent basis, with a minimum of media and time. However, there are some trade-offs. First, the interval between backups should be kept to a minimum (once a day at least). To guard against data loss as a result of a media failure (a rare but possible occurrence), it is a good idea to capture active files on (at least) two sets of dump volumes. Keep unnecessary duplication of files to a minimum to save both operator time and media storage. A third consideration is the ease with which a particular backed up version of a file can be located and restored. The following four-week schedule offers a reasonable trade-off between these goals. Sun Mon Tue Wed Thu Fri Week 1: Full 5 5 5 5 3 Week 2: 5 5 5 5 3 Week 3: 5 5 5 5 3 Week 4: 5 5 5 5 3 Although the Tuesday through Friday incrementals contain extra copies of files from Monday, this scheme assures that any file modified during the week can be recovered from the previous day's incremental dump. Dump Parameters Since it is suggested that the C option be used instead of the density and size options, and since those values are almost never really correct for any tape drive except 9 track tapes, recommended values for these parameters are no longer suggested in this man page. As an example of the capacity, a typical QIC150 cartridge would use C 140k, a DDS1 90 meter DAT or 112 meter 8mm (8200 mode) cartridge would use C 1800k, and a DDS2 120 meter cartridge would use C 3800k. EXAMPLES /dev/usr /usr efs rw,raw=/dev/rdsk/dks0d1s6 0 0 Here are a few examples on how to dump the /usr filesystem with the above /etc/fstab entry. dump 0Cfu 140k guest@kestrel:/dev/tape /usr does a level 0 dump of /usr onto a remote cartridge tape device /dev/tape on host kestrel using the guest account. dump also updates the file /etc/dumpdates. dump 2Cu 140k /usr does a level 2 dump of /usr to the local cartridge tape device /dev/tape and also updates the file /etc/dumpdates. dump 0Cb 140k 128 /usr does a level '0' dump of /usr to the local tape device /dev/tape using a blocking factor of 128. The tape is specified to have a capacity of 140 megabytes in the second, which allows for retries, space lost to repositioning, and so on. It is also appropriate for a QIC 150 quarter- inch tape drive. The ordering of the arguments depends on the ordering of the key. dump 1Cf 140k /dev/mt/tps0d7 /usr dump 1Cf 140k /dev/mt/tps0d7 /dev/rdsk/dks0d1s6 both do a level 1 dump of /usr to the local cartridge tape. dump /usr does a level 9 dump of /usr to the local tape device /dev/tape and updates the file /etc/dumpdates. dump 9uCf 2048k /dev/mt/tps0d6nrnsv /os dump 9uCf 2m /dev/mt/tps0d6nrnsv /os Both do a level 9 dump of /os to the local tape device /dev/mt/tps0d6nrnsv where the tape device being used is an 8mm tape drive, and we are being somewhat optimistic about the capacity. dump W prints out, for each filesystem in /etc/dumpdates, the most recent dump date and level and highlights those filesystems that should be dumped. FILES /dev/tape default tape unit to dump to /etc/dumpdates new format dump date record /etc/fstab dump table: filesystems and frequency /etc/group to find group operator SEE ALSO restore(1M), rmt(1M), shutdown(1M), xfsdump(1M), xfsrestore(1M), wall(1), ctime(3C), fstab(4), group(4), rhosts(4), dump(5), mtio(7). DIAGNOSTICS While running, dump emits many verbose messages. The exit codes are 0 Normal exit 1 Startup errors encountered 3 Abnormal termination BUGS Fewer than 32 read errors on the filesystem are ignored. Each reel requires a new process, so parent processes for reels already written just hang around until the entire tape is written. dump with the W or w options does not report filesystems that have never been recorded in /etc/dumpdates, even if listed in /etc/fstab. It would be nice if dump knew about the dump sequence, kept track of the tapes scribbled on, told the operator which tape to mount when, and provided more assistance for the operator running restore. It is recommended that incremental dumps also be performed with the system running in single-user mode. dump needs accurate information regarding the length and density of the tapes used. It can dump the filesystem on multiple volumes, but since there is no way of specifying different sizes for multiple tapes, all tapes used should be at least as long as the specified/default length. If dump reaches the end of the tape volume unexpectedly (as a result of a longer than actual length specification), it aborts the entire dump. This can be a problem when writing multiple dumps to the same physical tape, or when the tape drive supports hardware compression, and it is not possible to determine the average compression ratio ahead of time. Currently the only solution to this problem in this version of dump is to be conservative in specifying capacity.