Hi Felix,
we've had cache pressure messages for a long time in our small
production cluster without seeing any negative impact to clients (or
the cluster). We don't use Ganesha but we export CephFS directories
via NFS. I guess NFS is the common denominator here.
In our case we started with a very low mds_cache_memory_limit value
(around 2 or 4 GB, we also started with only a few clients) and
increased it step by step, currently it is around 8 GB.
Cache status currently shows ~ 7.5 GB while top output shows 10.5 GB usage.
That seems to be enough for around 70 connected clients, although not
all of them are constantly active.
So I would suggest to increase memory in small steps to see if those
warnings go away.
Regards,
Eugen
Zitat von "Stolte, Felix" <f.stolte@xxxxxxxxxxxxx>:
Hey folks,
I keep getting ceph health warnings about clients failing to
respond to cache pressure. They always refer to sessions from
ganesha exports. I've read all threads regarding this issue, but
none of my changes resolved it. What I’ve done so far:
Ganesha.conf:
MDCACHE {
Dir_Chunk = 0;
NParts = 1;
Cache_Size = 1;
}
Attr_Expiration_Time = 0 in every export
mds_cache_memory_limit = 17179869184 on MDS Servers
I even set “client_oc = false” on the ganesha server, but this
doesn’t seem to be applied
My setup is ceph version 14.2.8 (All Server and clients. One active
MDS. Ganesha 2.8.3 runs on a dedicated Server.
ceph daemon mds.<active_mds> dump_mempools (filtered out the empty pools):
"mempool": {
"by_pool": {
"bloom_filter": {
"items": 1414723,
"bytes": 1414723
},
"buffer_anon": {
"items": 180992,
"bytes": 2404306271
},
"buffer_meta": {
"items": 178660,
"bytes": 15722080
},
"osdmap": {
"items": 4121,
"bytes": 75912
},
"mds_co": {
"items": 221728924,
"bytes": 16320868177
},
},
"total": {
"items": 223507420,
"bytes": 18742387163
Every hint how to resolve the issue are welcome. If more information
is needed, I am glad to provide it.
Regards Felix
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