dRAID Expansion Planning Question

[NugentS]

Whilst I can't answer your question - an RMS-200 on a 25Gb NIC isn't big enough. You need 5 seconds of maximum network transfer as default for the ZIL, and I did read somewhere that actually there are three different logs - so would want 3 times that - but I am unsure how valid that assertion is (and I can only find the one reference).
Either way an RMS-200 (8GB I think) ain't big enough, unless you have found a 16GB model that I thought was a myth.
5 seconds of 25Gb = 15.625 GB (assuming my math is is correct, and assuming no overhead, and assuming my three logs is incorrect)

 

[Arwen]

@TrumanHW - Just because dRAID is now included with OpenZFS 2.1.x, and TrueNAS SCALE, (don't know about CORE), has that version of ZFS, does not mean you want to jump on the band wagon now.

Lots of lower level things need to be completed before TrueNAS SCALE or CORE will be a good platform for ZFS dRAID. Same applies to RAID-Zx column expansion. Just because ZFS started supporting it, does not imply instant support from TrueNAS.

Other than testing, what is the hurry?

Yes, you may benefit from some of the newer features not yet supported by the GUI or TrueNAS. But, that may not be a bad thing from a data reliability point of view.

 

[Samuel Tai]

Am I wrong in believing you can use dRAID now?

Unfortunately, yes. dRAID won't be available until OpenZFS 2.1, which won't arrive until TrueNAS 13.

 

[TrumanHW]

Afaik ZFS cannot expand draid vdevs, and the upcoming raidz expansion feature could be adapted to also work on draid, but hasn’t been.

With current tech, your best bet is multiple raidz3 vdevs, one per year. The drawback is the longer rebuild time compared to draid.

And, if any of stripe (assuming he's not just adding mirrors) fail, all data is contingent on recovery of a single stripe. Whereas dRAID's resilience always increases & recovery-speed scales as devs increase, expanding via RAIDz stripes increases the odds. Of course 3 Parity devs is good, but a RAIDz3 been lost before.

I tried making his layout nice(r) to look at & made a Tab Delimited TXT File.