Note: This is a beta release of Red Hat Bugzilla 5.0. The data contained within is a snapshot of the live data so any changes you make will not be reflected in the production Bugzilla. Also email is disabled so feel free to test any aspect of the site that you want. File any problems you find or give feedback here.
Bug 163823 - gfs_tool reclaim explanation
Summary: gfs_tool reclaim explanation
Alias: None
Product: Red Hat Cluster Suite
Classification: Retired
Component: gfs
Version: 3
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: michael conrad tadpol tilstra
QA Contact: GFS Bugs
Depends On:
TreeView+ depends on / blocked
Reported: 2005-07-21 14:05 UTC by Bastien Nocera
Modified: 2010-01-12 03:06 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2005-07-27 19:31:14 UTC

Attachments (Terms of Use)

Description Bastien Nocera 2005-07-21 14:05:35 UTC
Using GFS on a 4 node cluster. In a regular base we run into the problem where a
large amount of the available storage is used in meta data.

For example on this partition
/dev/pool/gpo_worko    17G  7.0G  9.3G  43% /worko

And a 100MB file could not be written.

The problem goes away as soon as 'gfs_tool reclaim' is issued.

There is not a single usage pattern, it varies from 100000s of small files,
which are written and deleted a couple times a second, up to a 1TB file, that is
written, and sometimes deleted.

Questions are:
- is the behaviour supposed to be like this?
- if it is, is it planned to change it?
- is it recommended to run "gfs_tool reclaim" every couple of hours through cron?

Comment 1 michael conrad tadpol tilstra 2005-07-27 19:31:14 UTC
gfs grabs free blocks as needed and makes them into meta-data blocks.  Once a
block is marked as meta-data, it remains as meta-data even if it isn't being
used.  gfs_tool reclaim can be used to convert these back.  Doing so locks the
entire fs while the reclaim takes place.  The reason for keeping meta-data
blocks around like this is a bit of a kludge to deal with the way nfs server is

From the above, the best responses are (one of these should be enough.)
- Change the usage pattern
- If the work load is from some kind of batch system, add gfs_tool reclaim to
part of the batch job.
- create two seperate filesystems, one for the tiny files, one for the larger.
- create a single fs that is large enough that it can have all of the unused
meta-data and large files.

Note You need to log in before you can comment on or make changes to this bug.