[zfs-discuss] Re: degradation of performance due to lots of use SUnreclaim memory(?)

Nikola M. minikola at gmail.com
Sat Dec 27 07:09:02 EST 2014


On 12/27/14 12:26 PM, peter.volkov at gmail.com wrote:
> Thanks for feedback, Michael and Tren. I'll answer your questions 
> below and since this happened again I've gathered more information. 
> Also I wanted to note that we have two servers with similar 
> configuration and similar problems on both, so this does not look like 
> hardware problem.
Do you use deduplication? Deduplication needs certain amount of RAM per 
data deduplicated.
Do you use SAS to SATA disk extenders? Chips on them can make unexpected 
hiccups.
Have you done zpool scrub lately? Since I see your disk configuration is 
in raidz1 groups, that allow only one disk per group to fail before you 
lose data on all pool.

OpenZFS on disk format is multiplatform so you can prepare new system 
disk and boot server from it. Put some illumos base distribution 
(smartos, omnios, xstreamos, openindiana) or other Linux install, import 
pool and run your applilcation on linux inside aether kvm virtual 
machine or virtualbox or new Linux install.

That is to see if problem is with ZfsOnLinux implementation, ZFS 
configuration or it is about application. Also maybe it is good thing to 
have application running on separate machine that is not storage machine 
and writing over network so to isolate a problem.

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