I was looking after a Dell PowerEdge R420 server with a hardware RAID card in it, a PERC8 H710P Mini. Connected to this were two WD Blue 3D NAND SATA SSDs in RAID-1, that were handling a write-intensive database: Geth, in this case.
After 11 months of running without problems, I had reason to "resync" Geth, and the server could not keep up with the required IOPS.
Symptoms were Database compacting, degraded performance
messages for hours, without recovery, and read/write latency in excess of 20/70ms,
as measured by sudo iostat -mdx
and its r_await
and w_await
data.
The cause of this was that the RAID controller does not support TRIM on the SSD, and the SSD's performance degraded over time because of it.