Hi Adam,

We already have been running with "echo 0 > /proc/sys/portals/debug"
across all Lustre boxes: MDS, OSSs, clients.

Dear Lustre community: Please jump to the bottom for specific questions.
Thank you.

Since we switched to Lustre 2 weeks ago, we've noticed the following:

- The site and its various components seem to load faster
- The same measured through Keynote, a metrics and monitoring company,
report that on average, pages now load a bit slower. The _average_ page
load time in recent weeks and months used to be 1.7 - 2.1 sec; for the
past 2 weeks it has been 2.0 - 2.4 sec. Traffic levels have remained
unchanged.
- When we crawl the Lustre file system, say for indexing or
regular-expression substitution purposes, processing about 1MM files
takes ~50 min over NFS, and ~2 hrs on Lustre, for an identical set of
files.

We used to mount NFS with:

rw,rsize=8192,wsize=8192,soft,intr,async,nodev

We mount Lustre with:

defaults,_netdev       on most clients and
defaults,_netdev,flock on a couple of special clients running
applications like Subversion requiring exclusive file locks
defaults,_netdev,ro    on a few special clients

Additionally, we mount the OSTs on the OSSs with:

fstype ldiskfs
mountfsoptions extents,mballoc

On the MDS:

ls -1 /proc/fs/lustre/ldlm/namespaces/*/lru_size
/proc/fs/lustre/ldlm/namespaces/OSC_lustre1_ost1p_mds-prod/lru_size
/proc/fs/lustre/ldlm/namespaces/OSC_lustre1_ost2p_mds-prod/lru_size
cat /proc/fs/lustre/ldlm/namespaces/*/lru_size
1000
1000

On the clients:

ls -1 /proc/fs/lustre/ldlm/namespaces/*/lru_size
/proc/fs/lustre/ldlm/namespaces/MDC_lustre1_mds-prod_MNT_client-prod-f7f
23600/lru_size
/proc/fs/lustre/ldlm/namespaces/OSC_lustre1_ost1p_MNT_client-prod-f7f236
00/lru_size
/proc/fs/lustre/ldlm/namespaces/OSC_lustre1_ost2p_MNT_client-prod-f7f236
00/lru_size
cat /proc/fs/lustre/ldlm/namespaces/*/lru_size
400
400
400

/proc/fs/lustre/llite/fs0/max_read_ahead_mb
4

/proc/fs/lustre/llite/fs0/max_read_ahead_whole_mb
1

Specific questions:
1) I am not sure about max_read_ahead_whole_mb - it's unclear to me
whether 0 or 1 should be preferred here.
2) Should I prefer 2500 for
/proc/fs/lustre/ldlm/namespaces/MDC*/lru_size and 1000 or 1500 for
/proc/fs/lustre/ldlm/namespaces/OSC*/lru_size?
3) If yes, should I be setting this across the board, on the clients
only, or on the MDS/OSSs only?
4) In general, should I still stick to avoiding mounting with flock
unless explicitly required?

Thank you very much, Zlatin

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