On 05/11/2014 06:15, Marcus Reid wrote:
On Tue, Nov 04, 2014 at 06:13:44PM +0000, Steven Hartland wrote:
On 04/11/2014 17:22, Allan Jude wrote:
Justin Gibbs and I were helping George from Voxer look at the same issue
they are having. They had ~169GB in inact, and only ~60GB being used for

Are there any further debugging steps we can recommend to him to help
investigate this?
The various scripts attached to the ZS ARC behavior problem and fix PR
will help provide detail this.

I've seen it here where there's been bursts of ZFS I/O specifically
write bursts.

What happens is that ZFS will consume large amounts of space in various
UMA zones to accommodate these bursts.
If you push the vmstat -z that he provided through the arc summary
script, you'll see that this is not what is happening.  His uma stats
match up with his arc, and do not account for his inactive memory.

uma script summary:

     oused: 5.860GB, ofree: 1.547GB, ototal: 7.407GB
     zused: 56.166GB, zfree: 3.918GB, ztotal: 60.084GB
     used: 62.026GB, free: 5.465GB, total: 67.491GB

His provided top stats:

     Mem: 19G Active, 20G Inact, 81G Wired, 59M Cache, 3308M Buf, 4918M Free
     ARC: 66G Total, 6926M MFU, 54G MRU, 8069K Anon, 899M Header, 5129M Other

The big uma buckets (zio_buf_16384 and zio_data_buf_131072, 18.002GB and
28.802GB respectively) are nearly 0% free.

Still potentially accounts for 5.4GB of your 20GB inact.

The rest could be malloc backed allocations?

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