[Gluster-users] [Draf] Troubleshooting process for files inaccessible to Gluster native clients

Burnash, James jburnash at knight.com
Tue Jun 21 19:33:51 UTC 2011


Looking for feedback / corrections to my logic for trying to preemptively scan GlusterFS storage for inconsistent file conditions that may prevent access from GlusterFS clients.

This is only targeted to the 3.1.x software releases, though may be applicable to earlier and later versions.

Steps to troubleshoot client access problems (reorder when a reasonable process has been nailed down)

Check client for:
is gluster-client service running?
are GlusterFS mount points present and accessible
can other files in the same directory be accessed?
do file permissions as presented to the client prohibit client from performing whatever access is being attempted?
does lsof show the file, or the directory path to the file in use?
Check backend storage servers for:
file presence on one pair of mirrors, and that if the file exists on the other pair of mirrors it is a GlusterFS symlink (perm 0000)
file permissions are consistent across all bricks
file attributes are consistent for all occurrences of the file (unless file is a GlusterFS symlink)

Logic for storage server check:
1) find all files with permissions of 0000 (GlusterFS symlink)
2) check extended attribute of each file
3) if attribute is trusted.glusterfs.dht.linkto, lookup indicated bricks and servers contained in that replica set (e.g pfs-ro1-replicate-11\000)
4) check to see that actual (normal) file exists on both of those bricks (e.g, pfs-ro1-client-22 and pfs-ro1-client-23).
5) if file does NOT exist, log to error file

Possible auto correction steps:
1) if error file exists, process it by removing Gluster LINK files, then
2) copy error file to Gluster client node
3) on that client node, copy missing files from source to native gluster mount

This is the type of tool that would not only be helpful to administrators, but would increase confidence in the state of the GlusterFS storage system.

I believe that the development team is working to incorporate some of this type of functionality in newer releases of the GlusterFS software - but some of us are stuck running what we are currently running until we can make compelling arguments for the stability of newer releases.

James Burnash
Unix Engineer
Knight Capital Group




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