[gpfsug-discuss] HAWC (Highly available write cache)

[Tejas Rao]

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.