[Lustre-discuss] MDS sizing question
prescott at hpc.ufl.edu
Thu Oct 23 05:33:51 PDT 2008
I am considering hardware requirements for an
MDS to be paired with a 500TB Lustre filesystem.
I have a question regarding the sizing guidelines
described in the manual.
For an anticipated average file size of 1MB, the
MDT size guideline from section 21.3.2 works out
to 4TB. For comparison, on our production 28TB
Lustre filesystem, we have:
# lfs df
UUID 1K-blocks Used Available Use% Mounted on
ufhpc-MDT0000_UUID 213655168 17329964 196325204 8%
filesystem summary: 29966190744 20728270148 9237920596 69% /ufhpc/scratch
# lfs df -i
UUID Inodes IUsed IFree IUse% Mounted on
ufhpc-MDT0000_UUID 61049728 21416476 39633252 35%
filesystem summary: 61049728 21416476 39633252 35% /ufhpc/scratch
My concern is that if I follow the guidelines, I would
over-provision the MDS with space we would never use.
I understand the inodes are pre-allocated and won't show up in
the "Used" column above. Under what conditions would the actual
MDT space get used more significantly?
UF HPC Center
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