Hi
I'm adding a sparse file to my SLOG device for mirroring since there is only 1 SSD available on my current FreeBSD storage. Performance wise is close to the purely SSD based SLOG. What I'm concerning is will it able to prevent data loss due to my SLOG SSD death?
The storage consists of 2 zfs pool which are zroot and vol. The SLOG was added at the vol but the sparse file is sitting on the zroot with sync=disabled, atime=off, compression=on and recordsize=128k for better write performance.
I'm getting the following tps on ESXI virtual machine when SLOG device is not present:
Below is the zpool status after adding the ssd and sparse file as a mirrored SLOG：
Performance on during dd with 4k write, tps is much higher than before
I guess the data on slog will survive after power outage as long as the ssd is there, correct me if I'm wrong.
Is adding a sparse file as slog mirror is necessary? Will zfs keep the data on SLOG in RAM automatically to prevent data loss when slog SSD sudden death?
Can we apply the same theory on ram disk pair with SSD instead of sparse file for mirroring?
Thanks.
I'm adding a sparse file to my SLOG device for mirroring since there is only 1 SSD available on my current FreeBSD storage. Performance wise is close to the purely SSD based SLOG. What I'm concerning is will it able to prevent data loss due to my SLOG SSD death?
The storage consists of 2 zfs pool which are zroot and vol. The SLOG was added at the vol but the sparse file is sitting on the zroot with sync=disabled, atime=off, compression=on and recordsize=128k for better write performance.
I'm getting the following tps on ESXI virtual machine when SLOG device is not present:
Code:
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda3 15.00 0.00 0.06 0 0
sda3 106.00 0.00 0.98 0 0
sda3 311.88 0.00 1.57 0 1
sda3 259.00 0.00 1.01 0 1
sda3 139.00 0.00 0.54 0 0
sda3 23.00 0.00 0.09 0 0
sda3 380.00 0.00 1.89 0 1
sda3 249.00 0.00 0.97 0 0
sda3 59.41 0.00 0.24 0 0
sda3 5.00 0.00 0.71 0 0
sda3 185.00 0.00 1.54 0 1Below is the zpool status after adding the ssd and sparse file as a mirrored SLOG：
Code:
NAME STATE READ WRITE CKSUM
vol ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada0p3 ONLINE 0 0 0
ada1p3 ONLINE 0 0 0
mirror-1 ONLINE 0 0 0
ada2p3 ONLINE 0 0 0
ada3p3 ONLINE 0 0 0
logs
mirror-2 ONLINE 0 0 0
md0.nop ONLINE 0 0 0
ada4p1 ONLINE 0 0 0
cache
ada4p2 ONLINE 0 0 0Performance on during dd with 4k write, tps is much higher than before
Code:
Device: tps MB_read/s MB_wrtn/s MB_read MB_wrtn
sda3 1361.00 0.01 5.68 0 5
sda3 1509.00 0.25 6.33 0 6
sda3 1151.49 0.02 5.09 0 5
sda3 1848.00 0.02 7.43 0 7
sda3 1099.00 0.65 4.23 0 4
sda3 1765.00 0.00 6.89 0 6
sda3 1714.00 0.00 6.77 0 6
sda3 1754.00 0.00 6.93 0 6
sda3 1873.00 0.00 7.88 0 7
sda3 1478.00 0.02 5.75 0 5
sda3 1806.00 0.00 7.49 0 7
sda3 1086.00 0.00 4.57 0 4
sda3 2024.75 0.00 7.91 0 7I guess the data on slog will survive after power outage as long as the ssd is there, correct me if I'm wrong.
Is adding a sparse file as slog mirror is necessary? Will zfs keep the data on SLOG in RAM automatically to prevent data loss when slog SSD sudden death?
Can we apply the same theory on ram disk pair with SSD instead of sparse file for mirroring?
Thanks.