Split Optane Drive for LOG/CACHE and mirror?

[ksdmg]

Hello guys,
I just setup a Optane P900 PCIE card as cache and log, so both on one drive with different partitions.
I did this by creating two partitions on the card and then:

Code:

zpool add ironwolf log /dev/nvme0n1p1
zpool add ironwolf cache /dev/nvme0n1p2

This works fine, however, it doesn't have any redundancy for the log. Is there any way to mirror this setup? Would I simply add another optane and execute the same commands on the new drive?

 

[artlessknave]

no. what you are trying to do is unsupported. Truenas supports only dedicating drives to a single pool; trying what you are trying might "work" NOW but fail later, usually in unexpected ways. there is no middleware support for what you have done in the CLI.

additionally:

• you dont have enough RAM for l2arc.
• you dont need to mirror L2ARC ( I don't even think you can)
• SLOG is unlikely to do anything for you. (ONLY applies to sync writes, which are usually only used for things like VM or Database storage. smb cannot interact with sync functionality)
• you have drives far over the raidz1 max recommended size of 2TB

 

[ksdmg]

I know that this is not supported and I only wanted to mirror the SLOG, but I understood that it does not work how I've set it up.
It does a lot for me but not in a way it was supposed to. I wanted to reduce noise on HDD activity, and it achieves this perfectly.
Thanks for you answer!

 

[Stux]

IIRC, the only reason to mirror a LOG drive is to protect in flight writes that occur just before a spontaneous reboot, and have not yet been flushed to disk, where the drive then fails during the reboot.

This won't actually destroy your pool.

So unless you have a true mission critical data store where you can't afford to lose a second of writes, don't worry about it

And if you were running a true mission critical data store, you wouldn't be mucking about in the terminal of an appliance splitting optanes.

PS: I split optanes too.

 

[joeschmuck]

What you are asking to do can be done. Go with your gut, get experimental, I have done that kind of stuff as well but after trying it, I dumped it because I didn't need it and keeping things simple is generally the best way to go. But it is true, you do not have enough RAM for a L2ARC. You will succeed in slowing your system down if you do.