dasalvager - Initializes the Salvager component of the dafs process
dasalvager [initcmd] [-partition <name of partition to salvage>] [-volumeid <volume id to salvage>] [-debug] [-nowrite] [-inodes] [-force] [-oktozap] [-rootinodes] [-salvagedirs] [-blockreads] [-parallel <# of max parallel partition salvaging>] [-tmpdir <name of dir to place tmp files>] [-showlog] [-showsuid] [-showmounts] [-orphans (ignore | remove | attach)] [-help]
The dasalvager command initializes the Salvager component of the dafs process.
In the conventional configuration,
its binary file is located in the /usr/afs/bin directory on a file server machine.
The Salvager restores internal consistency to corrupted read/write volumes on the local file server machine where possible. For read-only or backup volumes, it inspects only the volume header:
If the volume header is corrupted, the Salvager removes the volume completely and records the removal in its log file, /usr/afs/logs/SalvageLog. Issue the vos release or vos backup command to create the read-only or backup volume again.
If the volume header is intact, the Salvager skips the volume (does not check for corruption in the contents). However, if the File Server notices corruption as it initializes, it sometimes refuses to attach the volume or bring it online. In this case, it is simplest to remove the volume by issuing the vos remove or vos zap command. Then issue the vos release or vos backup command to create it again.
Unlike other server process initialization commands, the Salvager command is designed to be issued at the command shell prompt, as well as being placed into a file server machine's /usr/afs/local/BosConfig file with the bos create command. It is also possible to invoke the Salvager remotely by issuing the bos salvage command.
Combine the command's options as indicated to salvage different numbers of read/write volumes:
To salvage all volumes on the file server machine, provide no arguments. No volumes on the machine are accessible to Cache Managers during the salvage, because the BOS Server stops the File Server and Volume Server processes while the Salvager runs.
To salvage all of the volumes on one partition, provide the -partition argument. As for a salvage of all volumes on the machine, no volumes on the machine are accessible to Cache Managers during the salvage operation.
To salvage only one volume, combine the -partition and -volumeid arguments. Only that volume is inaccessible to Cache Managers, because the BOS Server does not shutdown the File Server and Volume Server processes.
The Salvager normally salvages only those read/write volumes that are marked as having been active when a crash occurred. To have it salvage all relevant read/write volumes, add the -force flag.
The Salvager normally creates new inodes as it repairs damage. If the partition is so full that there is no room for new inodes, use the -nowrite argument to bringing undamaged volumes online without attempting to salvage damaged volumes. Then use the vos move command to move one or more of the undamaged volumes to other partitions, freeing up the space that the Salvager needs to create new inodes.
By default, multiple Salvager subprocesses run in parallel: one for each partition up to four, and four subprocesses for four or more partitions. To increase or decrease the number of subprocesses running in parallel, provide a positive integer value for the -parallel argument.
If there is more than one server partition on a physical disk,
the Salvager by default salvages them serially to avoid the inefficiency of constantly moving the disk head from one partition to another.
However,
this strategy is often not ideal if the partitions are configured as logical volumes that span multiple disks.
To force the Salvager to salvage logical volumes in parallel as if they were on separate disks,
provide the string all as the value for the -parallel argument.
To set both parameters at the same time,
append the number of Salvager processes to the string all.
For example,
-parallel all5 treats each partition as a separate disk and runs five Salvager processes,
thus salvaging five partitions at a time.
The Salvager creates temporary files as it runs, by default writing them to the partition it is salvaging. The number of files can be quite large, and if the partition is too full to accommodate them, the Salvager terminates without completing the salvage operation (it always removes the temporary files before exiting). Other Salvager subprocesses running at the same time continue until they finish salvaging all other partitions where there is enough disk space for temporary files. To complete the interrupted salvage, reissue the command against the appropriate partitions, adding the -tmpdir argument to redirect the temporary files to a local disk directory that has enough space.
The -orphans argument controls how the Salvager handles orphaned files and directories that it finds on server partitions it is salvaging. An orphaned element is completely inaccessible because it is not referenced by the vnode of any directory that can act as its parent (is higher in the filespace). Orphaned objects occupy space on the server partition, but do not count against the volume's quota.
To generate a list of all mount points that reside in one or more volumes, rather than actually salvaging them, include the -showmounts flag.
This command does not use the syntax conventions of the AFS command suites. Provide the command name and all option names in full.
Accommodates the command's use of the AFS command parser, and is optional.
Specifies the name of the partition to salvage. Specify the full partition name using the form /vicepx or /vicepxx. Omit this argument to salvage every partition on the file server machine.
Specifies the volume ID of a specific read/write volume to salvage. The -partition argument must be provided along with this one and specify the volume's actual site.
Allows only one Salvager subprocess to run at a time, regardless of the setting of the -parallel option. Include it when running the Salvager in a debugger to make the trace easier to interpret.
Brings all undamaged volumes online without attempting to salvage any damaged volumes.
Records in the /usr/afs/logs/SalvageLog file a list of all AFS inodes that the Salvager modified.
Inspects all volumes for corruption, not just those that are marked as having been active when a crash occurred.
Removes a volume that is so damaged that even issuing the vos zap command with the -force flag is ineffective. Combine it with the -partition and -volumeid arguments to identify the volume to remove. Using this flag will destroy data that cannot be read, so use only with caution and when you're certain that nothing in that volume is still needed.
Records in the /usr/afs/logs/SalvageLog file a list of all AFS inodes owned by the local superuser root.
Salvages entire directory structures, even if they do not appear to be damaged. By default, the Salvager salvages a directory only if it is flagged as corrupted.
Forces the Salvager to read a partition one disk block (512 bytes) at a time and to skip any blocks that are too badly damaged to be salvaged. This allows it to salvage as many volumes as possible. By default, the Salvager reads large disk blocks, which can cause it to exit prematurely if it encounters disk errors. Use this flag if the partition to be salvaged has disk errors.
Specifies the maximum number of Salvager subprocesses to run in parallel. Provide one of three values:
An integer from the range 1 to 32.
A value of 1 means that a single Salvager process salvages the partitions sequentially.
The string all to run up to four Salvager subprocesses in parallel on partitions formatted as logical volumes that span multiple physical disks.
Use this value only with such logical volumes.
The string all followed immediately (with no intervening space) by an integer from the range 1 to 32,
to run the specified number of Salvager subprocesses in parallel on partitions formatted as logical volumes.
Use this value only with such logical volumes.
The BOS Server never starts more Salvager subprocesses than there are partitions, and always starts only one process to salvage a single volume. If this argument is omitted, up to four Salvager subprocesses run in parallel but partitions on the same device are salvaged serially.
Names a local disk directory in which the Salvager places the temporary files it creates during a salvage operation, instead of writing them to the partition being salvaged (the default). If the Salvager cannot write to the specified directory, it attempts to write to the partition being salvaged.
Displays on the standard output stream all log data that is being written to the /usr/afs/logs/SalvageLog file.
Displays a list of the pathnames for all files that have the setuid or setgid mode bit set.
Records in the /usr/afs/logs/SalvageLog file all mount points found in each volume. The Salvager does not repair corruption in the volumes, if any exists.
Controls how the Salvager handles orphaned files and directories. Choose one of the following three values:
Leaves the orphaned objects on the disk, but prints a message to the /usr/afs/logs/SalvageLog file reporting how many orphans were found and the approximate number of kilobytes they are consuming. This is the default if the -orphans argument is omitted.
Removes the orphaned objects, and prints a message to the /usr/afs/logs/SalvageLog file reporting how many orphans were removed and the approximate number of kilobytes they were consuming.
Attaches the orphaned objects by creating a reference to them in the vnode of the volume's root directory. Since each object's actual name is now lost, the Salvager assigns each one a name of the following form:
__ORPHANFILE__.index for files.__ORPHANDIR__.index for directories.where index is a two-digit number that uniquely identifies each object. The orphans are charged against the volume's quota and appear in the output of the ls command issued against the volume's root directory.
Prints the online help for this command. All other valid options are ignored.
The following command instructs the Salvager to attempt to salvage the volume with volume ID 258347486 on /vicepg on the local machine.
% /usr/afs/bin/dasalvager -partition /vicepg -volumeid 258347486
To issue the command at the shell prompt, the issuer must be logged in as the local superuser root.
BosConfig(5), SalvageLog(5), bos_create(8), bos_getlog(8), bos_salvage(8), vos_move(1)
IBM Corporation 2000. <http://www.ibm.com/> All Rights Reserved.
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