We are benchmarking a test machine which has:
8 cores, 64GB RAM
12 * 12 TB HDD (SATA)
2 * 480 GB SSD (SATA)
1 * 240 GB SSD (NVME)
Ceph Mimic
Baseline benchmark for HDD only (Erasure Code 4+2)
Write 420 MB/s, 100 IOPS, 150ms latency
Read 1040 MB/s, 260 IOPS, 60ms latency
Now we moved WAL to the SSD (all 12 WALs on single SSD, default size (512MB)):
Write 640 MB/s, 160 IOPS, 100ms latency
Read identical as above.
Nice boost we thought, so we moved WAL+DB to the SSD (Assigned 30GB for DB)
All results are the same as above!
Q: This is suspicious, right? Why is the DB on SSD not helping with our benchmark? We use rados bench
We tried putting WAL on the NVME, and again, the results are the same as on SSD.
Same for WAL+DB on NVME
Again, the same speed. Any ideas why we don't gain speed by using faster HW here?
Jan
--
Jan Senko, Skype janos-
Phone in Switzerland: +41 774 144 602
Phone in Czech Republic: +420 777 843 818
Phone in Switzerland: +41 774 144 602
Phone in Czech Republic: +420 777 843 818
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