ZFS with log drive

[limer]

Some questionsa about https://pve.proxmox.com/wiki/ZFS_on_Linux

SSD with power-loss protection
This seems PLP in SSD drives ?

If all log devices fail the ZFS main pool itself will be used again, until the log device(s) get replaced.
Scenario. I have one disk for ZIL, not in RAID, single disk added to pool. When this disk failed - what will happened Operations with sync=always maybe lost ?
Maybe the best option is ZFS RAID 1 for security ?

 

[UdoB]

This seems PLP in SSD drives ?

Yes. And the same is true for NVMe!

Scenario. I have one disk for ZIL, not in RAID, single disk added to pool. When this disk failed - what will happened Operations with sync=always maybe lost ?

No! Okay, probably not - as long as no other failures adds up:

SLOG is basically "write only". The only moment it is read from it is when data could not be written to the data disks during the next few seconds, for example because of a power failure. In this case SLOG is read from during the next startup.

Maybe the best option is ZFS RAID 1 for security ?

Technically: yes.

But the more important aspect is to check if you really enhance your situation with a Separate LOG. It really only helps to quickly acknowledge SYNC writes. In a more common setup these may be rare. The most common usecase is the wide field of Databases.