[gpfsug-discuss] HAWC (Highly available write cache)
Tejas Rao
raot at bnl.gov
Mon Aug 1 19:36:15 BST 2016
I have enabled write cache (HAWC) by running the below commands. The
recovery logs are supposedly placed in the replicated system metadata
pool (SSDs). I do not have a "system.log" pool as it is only needed if
recovery logs are stored on the client nodes.
mmchfs gpfs01 --write-cache-threshold 64K
mmchfs gpfs01 -L 1024M
mmchconfig logPingPongSector=no
I have recycled the daemon on all nodes in the cluster (including the
NSD nodes).
I still see small synchronous writes (4K) from the clients going to the
data drives (data pool). I am checking this by looking at "mmdiag
--iohist" output. Should they not be going to the system pool?
Do I need to do something else? How can I confirm that HAWC is working
as advertised?
Thanks.
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