I am renting two identical physical servers (at Serverloft). These servers come with 2x512 GB SSD disks, and I've set them up with mdadm in a RAID1. The disks are locally installed in the server.
The write performance on these two systems seem to differ dramatically.
According to lshw -short
, the controller is :
C610/X99 series chipset 6-Port SATA Controller [AHCI mode]
1st server (2 x SAMSUNG MZ7TE512)
host02:/tmp# dd bs=1M count=8192 if=/dev/zero of=testfile conv=fdatasync
8192+0 records in
8192+0 records out
8589934592 bytes (8.6 GB) copied, 38.4952 s, 223 MB/s
2nd server (2 x SAMSUNG MZ7LN512)
host03:/tmp# dd bs=1M count=8192 if=/dev/zero of=testfile conv=fdatasync
8192+0 records in
8192+0 records out
8589934592 bytes (8.6 GB) copied, 108.284 s, 79.3 MB/s
Besides from the fact that the write performance overall is really bad, what can cause this huge gap in performance. The gap is consistent over several runs.
For comparison, I've got a 3rd server as well with 2x2TB SATA disks.
host01:/tmp# dd bs=1M count=8192 if=/dev/zero of=testfile conv=fdatasync
8192+0 records in
8192+0 records out
8589934592 bytes (8.6 GB) copied, 49.0217 s, 175 MB/s
What have I done?
- Validated that disk partitions are aligned (
parted
>align-check opt n
) fstrim -v /
(fails on 2nd server, succeeds on 1st server)blockdev --getbsz [partition]
gives a block size of 4096 (default, I believe)- Mounted drives with
defaults,errors=remount-ro
in /etc/fstab
What (more) can I do to improve write performance on these systems?