TrueNAS/FreeNAS scrub/resilver times

[nelem]

Firstly, my setup:
NAS1

CPU	Intel(R) Pentium(R) CPU G4400 @ 3.30GHz (AES-NI)
mb	ASUSTeK P10S-I Series
Memory	16GB ECC
HDD	4x6TB Wed Red Plus RAIDZ2 GELI Encrypted

Backup NAS

MB	ASRock E3C224D2I (No AES-NI)
CPU	Intel(R) Pentium(R) CPU G3260 @ 3.30GHz
Memory	8GB ECC
HDD	4x6TB Wed Red Plus RAIDZ2 GELI Encrypted

I have recently tried the upgrades and noticed increasingly slow scrub/resilver times on the later versions against what is essentially the same pool. The second figures for the 11.3-U5 version are the most recent and very consistent with the earlier scrubs on the same version.

	Backup NAS (no AES-NI)			NAS (AES-NI)
Version	Scrub	Resilver		Scrub	Resliver
11.1-U7	1d14h03m33s			11h36m57s	14h32m45s
11.3-U5	1d05h51m46s	1d06h52m02s		11h37m51s	17h16m03s
	1d05h25m44s	1d08h10m08s		11h55m30s	17h53m54s
12.0.-U8.1	1d7h31m48s			18h01m55s	2d04h44m05s
	1d8h46m35s
13.0-U5.3	2d14h49m13s			1d17h27m09s	3d14h16m57s
	3d14h07m59s			1d18h57m33s

Do the later versions do a better/more thorough job to justify the extra time? Are there any tuneables for the later version that I should look at?

Cheers, Tony

 

[Arwen]

The updated ZFS scrub & re-silver code was likely not taking into account full disk encryption below it, (aka GELI Encryption of the disk partitions).

Also, you don't list if your pools have gone past certain fullness thresholds. At 95% full, (or is it lower?), ZFS goes into space reclaimation over speed mode. The general rules of thumb is to keep pools at 80% or less, to reduce fragmentation.

It is probable that at some point GELI encrypted disk partitions will not be supported at all. Meaning you would not be able to update further until that has been removed. I vaguely recall it being mentioned that creating GELI encryption is no longer supported on the latest TrueNAS Core. But, someone else can speak to that aspect.

 

[nelem]

Thanks, Arwen.

There is one pool at about 67% full and fragmentation of 1% (due to me restoring the whole pool after I lost it)