[Bugs] [Bug 1333224] New: read/write performance degrades as the cache tier fills up

[bugzilla at redhat.com]

https://bugzilla.redhat.com/show_bug.cgi?id=1333224

            Bug ID: 1333224
           Summary: read/write performance degrades as the cache tier
                    fills up
           Product: GlusterFS
           Version: 3.7.10
         Component: tiering
          Severity: low
          Priority: medium
          Assignee: bugs at gluster.org
          Reporter: pcuzner at redhat.com
        QA Contact: bugs at gluster.org
                CC: bugs at gluster.org



Description of problem:
During a continuous write workload, writes were accelerated by the cache layer
up until the low watermark was reached. At this point performance to the client
degraded to pre-cache levels. 

Version-Release number of selected component (if applicable):


How reproducible:
Tried several times, and each time the effect was observed

Steps to Reproduce:
1. create a tier volume with SSD as the tier
2. create files on the volume with dd repeatedly
3. observe throughput degradation as the tier >  60% utilised

Actual results:
client writes degrade considerably

Expected results:
client writes should degrade, but I saw 150MB/s become 4MB/s

Additional info:
The test environment I used was vm's under KVM. Each gluster node has an SSD
disk for hot, and a replica 2 for cold tier.

-- 
You are receiving this mail because:
You are the QA Contact for the bug.
You are on the CC list for the bug.
You are the assignee for the bug.