Is the Radian-RMS-200 exempt from TrueNAS suggested-requirement that Zils be mirrored..?

[TrumanHW]

I followed a member's suggestion & grabbed a Radian RMS-200
...but TrueNAS wants me to either use FOUR drives (RAIDz2) .... or to STRIPE it ..??

So, either double the risk of a single-drive ... or ... use a 4-drive array ..?
I'm guessing that the RMS-200 as a ZIL is exempt ... as it has a BBU & the reliability claims...

So, Force the system to accept it alone..?

Thanks

 

[gea]

If you want to add a data z2 vdev, to a ZFS pool, you need at least 4 disks. If you want to add an Slog you need at least one disk. You can stripe or mirror them but this is not a ZFS requirement and it is uncritical.

If an Slog fails, ZFS simply reverts to onpool logging which is much slower on a pool from mechanical disks. You use a mirror mainly to avoid this slowdown on a failure or to avoid the minimal risk of a data loss in the ultra rare case that an Slog fails combined with a system crash.

 

[TrumanHW]

Cool, thank you. And ... 8GB is adequate for a ZIL, yes ..?
After maxing out RAM, this is the 2nd means for speeding up an array, yes .. ?

And for clarity -- an Slog is a ZIL ... so the answer is, Force away.
So it's a goofy thing that remains low priority for Devs to fix poorly worded choices:

• 4 ZILs (arbitrarily RAIDz2) or
• STRIPED (Double risk)
• FORCE to enable a (SINGLE DRIVE)

 

[gea]

If you add an Slog, the ZIL logging functionality is on that disk otherwise onpool
8 GB is ok (quite the needed minimum)
You cannot use a Z2 as an Slog, only basic, mirror or stripe

 

[TrumanHW]

You cannot use a Z2 as an Slog, only basic, mirror or stripe

Isn't it odd it only provides the option to use STRIPED devices though ..?

 

[gea]

I do not use TrueNAS to comment the menu options but basically a stripe with a single disk is a basic vdev

 

[TrumanHW]

It's not odd to act like 2x-risk is the safe option ..?
And not striping is the 'dangerous option' ..?? Requires a:
... "Force command" so you "understand how risky" your choice is ..??