[Linux-cluster] optimising DLM speed?
ajb2 at mssl.ucl.ac.uk
Wed Feb 16 19:07:10 UTC 2011
To add some interest (and give you numbers to work with as far as dlm
config tuning goes), here are a selection of real world lock figures
from our file cluster (cat $d | wc -l)
/sys/kernel/debug/dlm/WwwHome-gfs2_locks 162299 (webserver exports)
/sys/kernel/debug/dlm/soft2-gfs2_locks 198890 (Mainly IDL software -
it's hopelessly inefficient, 32Gb partition)
/sys/kernel/debug/dlm/home-gfs2_locks 74649 (users' /home directories,
/sys/kernel/debug/dlm/User1_locks 318337 (thunderbird, mozilla,
openoffice caches, 200gb partition)
/sys/kernel/debug/dlm/Peace04-gfs2_locks 265955 (solar wind data)
At the other end of the spectrum:
/sys/kernel/debug/dlm/xray0-gfs2_locks 24917 (solar observation data)
/sys/kernel/debug/dlm/cassini2-gfs2_locks 598 (cassini probe data from
/sys/kernel/debug/dlm/rgoplates-gfs2_locks 27 (global archive of 100
years' worth of photographic plates from Greenwich observatory)
Directories may have up to 90k entries in them, although we try very
hard to encourage users to use nested structures and keep directories
below 1000 entries for human readability (exceptions tend to be mirrors
of offsite archives), but the counterpoint to is that it drives the
number of directories up - which is why I was asking about the
~98% of directories are below 4000 entries.
FSes usually have 400k-2M inodes in use.
Does that help with tuning recommendations?
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