REPAIR(1)REPAIR(1)NAMErepair - Repair conflicts in the Coda Distributed File System
SYNOPSISrepair-d
repair-allowclear
repair object_in_conflict fixfile [ repair_options ]
DESCRIPTION
The Coda repair tool allows you to manually resolve two kinds of con‐
flicts resulted from partitioned updates. Server-server conflicts are
conflicting mutations performed on partitioned servers that can not be
automatically resolved. Local-global conflicts are caused by mutations
performed on a disconnected client that are in conflict with the global
server state.
To use the repair tool interactively, type repair at the command
prompt.
Server-Server conflicts can be repaired from the command line without
entering interactive mode. This is useful if you need to repair many
conflicts within a volume at a time and wish to write a shell script.
Please see the EXAMPLES section for examples on invoking complete
repair sequences from the command line.
A description of the repair commands follows:
beginrepair object
verifies that object is indeed in conflict. It will print out
messages to indicate whether the current repair session is for
server-server conflict or local-global conflict.
For a server-server repair session, this command locks the cor‐
responding volume and and mounts its individual replicas read-
only. It will inform the users to only use the comparedirs,
dorepair and removeinc commands to repair the conflict.
For a local-global repair session, both local and global repli‐
cas of object are visible at object/local (read-only) and
object/global (mutable and serving as the workspace for storing
the repair result for object). You need to iterate through the
current sessions local-mutations-list containing all the local
updates to object and its descendants. Each operation in local-
mutations-list must be accounted for and Venus maintains the
current-mutation being iterated. Use the checklocal command to
find out the conflict between the current-mutation and the
server state. Note that not all local mutations are necessarily
in conflict, and you can use the listlocal command to see all
the operations in local-mutations-list. You can advance the
iteration to the next operation using either the preservelocal
or the discardlocal command with the former replaying the cur‐
rent-mutation operation on the relevant global replicas. To
speed up the iteration, the preservealllocal command repeats
preservelocal until the local-mutations-list is exhausted or the
first replay failure. Similarly, the discardalllocal command
repeats discardlocal until exhausting the local-mutations-list.
You can use external tools such as emacs(1) to make direct
updates on needed replicas under object/global. Use the quit
command to either commit or abort the session.
quit If the current session is repairing a server-server conflict,
this command releases all the volume-level locks and causes the
repair tool to return to the shell. If the current session is
repairing a local-global conflict, this command asks you whether
to commit or abort the repair session. If you answer yes, the
mutations performed on the relevant global replicas will be com‐
mitted to the servers. Otherwise, the repair result will be
aborted as if this repair session has never happened.
help Prints out a help message.
Use the following commands to repair a server-server conflict:
comparedirs object fixfile [ -acl user rwlidka ] [ -mode newmode ] [
-owner username ]
Compares the mounted read-only replicas of a directory in con‐
flict and prints the repair commands in fixfile to make the
replicas identical. To print out the repair commands on your
terminal give stdout as the pathname for fixfile. Compensating
actions for Name/Name conflicts and Update/Update conflicts are
not given. The user is only told about their existence and
required to edit the fixfile manually. You should have already
done a beginrepair on object and this command works only if
object is a directory.
dorepair object fixfile
Does the actual repair of an object. If the repair succeeds,
each accessible replica will be marked consistent. You will be
prompted for the arguments if they are missing, and will be
asked to confirm the repair. You should have already done a
beginrepair on this object (or on on some other object in this
volume.). If object is a file or symbolic link, fixfile must
provide its new contents. If object is a directory, fixfile
must provide a sequence of directory repair commands for each
replica. The format of fixfile for directories is as follows:
replica <servername> <id of replica1>
<repair commands for replica1>
replica <servername> <id of replica2>
<repair commands for replica2>
and so on
Repair commands are given one per line. Blank lines are ok. id
of replica1, id of replica2, etc. are numbers that identify
each replica. These are the same as the volume ids of read-
write volumes corresponding to a replicated volume. The volume
ids can be obtained by doing an ls on the inconsistent object,
after the beginrepair command has succeeded. The directory
repair commands are:
createf <filename> <fid.0> <fid.1> <fid.2>
creates <symlinkname> <fid.0> <fid.1> <fid.2>
createl <linkname> <fid.0> <fid.1> <fid.2>
created <dirname> <fid.0> <fid.1> <fid.2>
removefsl <filename or symlinkname or linkname>
removed <dirname>
mv <srcname> <tgtname>
<src <fid.0> <fid.1> <fid.2>>
<target <fid.1> <fid.2>>
setacl <username> [rwlikda]
delacl <username>
setmode <newmode>
setowner <new owner name>
setmtime <new modified time>
Note that for the setacl command, the short form access rights
of all and none can also be used.
removeinc object
Removes the inconsistent object if it is file or a symbolic
link. If the object is a directory, all the descendants of the
object will be removed in all the accessible replicas and the
directory itself will be removed as long as its replicas are
identical. If the owner or the ACL of the directory replicas are
different, you have to repair the conflict first.
clearinc object
Compares the mounted read only replicas of a directory in con‐
flict and if the replicas are identical it clears the inconsis‐
tency flag of the replicas. Otherwise it will inform you about
the inequality of the replicas. You should run the comparedirs
command to find out the cause of conflict. This command should
be used only for directories. Files and symbolic links are
cleared of their inconsistency with the dorepair command.
The following commands are used only for repairing local-global con‐
flicts:
checklocal
Checks to see if the current-mutation being iterated by the cur‐
rent local-global repair session is in conflict with the server
state. It displays the operator and operand (s) of the current-
mutation operation and indicates whether it is in conflict with
the relevant server replicas. If it is in conflict, a brief rea‐
son of the conflict is given. Note that this command does not
advance the iteration of the local-mutations-list.
discardlocal
Simply advances the iteration of the local-mutations-list of the
current local-global repair session to the next operation. Use
this command when the user does not want the current-mutation
operation to have any effect on the repair result.
preservelocal
Tries to replay the current-mutation of the current local-global
repair session on the relevant global replicas. In other words,
it will try to preserve the effect of the current mutation in
the repair result. If the replay succeeds, the iteration of
local-mutations-list will be advanced to the next operation. The
effect of the replay is visible only on this client and not on
the server until the repair result is successfully committed. If
the replay fails, information about the reason of the failure
will be displayed.
discardalllocal
Repeatedly performs the discardlocal command until the local-
mutations-list is exhausted. Its effect is to finish the itera‐
tion and discard the effect of all the remaining mutations on
the repair result.
preservealllocal
Repeatedly performs the preservelocal command until the first
failure or the iteration of local-mutations-list is exhausted.
This command is used if the user wants to preserve the effect of
all the remaining mutation operations in the repair result.
listlocal
Prints out all the mutation operations in the local-mutations-
list of the current local-global repair session.
The following commands existed in old versions but are no longer sup‐
ported:
showreplicas object
Shows the names of the individual replicas of object, and the
pathnames by which these replicas may be examined read-only. A
beginrepair must have been done earlier on this object (or on
another object in the same volume).
unlockvolume pathname
Tells Venus to unlock the specified volume in repair. No
check is done to see if you locked the volume during this
repair session. The primary use of this command is to unlock
volumes that were locked during a previous, aborted, invocation
of the repair tool. The command will fail if Venus discovers
that you do not hold the repair lock on the server. This could
happen, for example, if your aborted repair occurred on another
workstation, or if you were not repairing the volume in the
first place.
EXAMPLES
This will cause repair to examine the object "common", generate a fix
file for it and in addition to the contents of the fix file, and set
the acl for hmpierce to rlidwka on the replica.
repair common /tmp/fix -acl hmpierce all
The same repair would look like this in interactive mode:
repair> beginrepair common
repair> comparedirs common /tmp/fix -acl hmpierce all
repair> dorepair common /tmp/fix
repair> endrepair
repair> quit
AUTHORS
· M. Satyanarayanan, 1989, Created
· Puneet Kumar, 1991, Substantially revised
· Joshua Raiff, 1993, Created man page
· Qi Lu, 1995, Added local-global repair commands and revised man page
· Henry M. Pierce, 1998, updated for command line options
Coda Distributed File System 25 April 2005 REPAIR(1)
