[ClusterLabs] DRBD and SSD TRIM - Slow!
eric.robinson at psmnv.com
Wed Aug 2 01:09:34 EDT 2017
Does anyone know why trimming a filesystem mounted on a DRBD volume takes so long? I mean like three days to trim a 1.2TB filesystem.
Here are some pertinent details:
OS: SLES 12 SP2
Drives: 6 x Samsung SSD 840 Pro 512GB
RAID: 0 (mdraid)
Latency: < 1ms
Iperf test: 900 mbits/sec
When I write to a non-DRBD partition, I get 400MB/sec (bypassing caches).
When I trim a non-DRBD partition, it completes fast.
When I write to a DRBD volume, I get 80MB/sec.
When I trim a DRBD volume, it takes bloody ages!
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