[Lustre-discuss] Unbalanced OSTs

syed haider syed.haider at gmail.com
Thu Feb 18 09:19:19 PST 2010

Forgive my novice understanding of lustre. Here is my current config:
1 combined MGS/MDT, 4 OSS's attached to DDN controller/SAN.

We have 32 1Tb OSTs (8 on each OSS) and because of the nature of our jobs,
the files written to lustre vary greatly (5MB ~ 400GB size files). I'm not
sure what algorithym lustre
uses to balance writes to the fs but we have very high inconsistencies in
disk space usage. One OST maybe only 40% full while another 94% full. This
is problematic because if one of our OST's fills up,
jobs begin to fail with out of disk space errors even though there are
terabytes of space unused. If someone can suggest a solution I would be
eteranally grateful.

The only solution I see is increasing each OST from 1TB to maybe 2 or 3TB?
So this lead me to my second question - what type of performance degradation
(if any)
am I looking at if increase the size of the OSTs? and is there a limit to
the size of OSTs? Any input is appreciated!

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