How to speed up slow zpool scrub?

[Andy Farkas]

On 27/04/2016 02:34, Miroslav Lachman wrote:
> DH wrote on 04/26/2016 17:47:
>>> 5GB of RAM
>>
>> That seems to be an insufficient amount of system ram when employing 
>> zfs.
>>
>> Take a look at this:
>>
>> http://doc.freenas.org/9.3/freenas_intro.html#ram
>
> I know 5GB is not much these days but is memory used for scrubbing a 
> lot? Because I am satisfied with working performance. The only concern 
> is slow scrubbing and I am not sure that more memory helps in this case.
>

CPU: Intel(R) Pentium(R) 4 CPU 3.00GHz (3000.02-MHz 686-class CPU)
real memory = 4294967296 (4096 MB)
avail memory = 3404075008 (3246 MB)
ACPI APIC Table: <INTEL D945GTP >
ad4: 3815447MB <ST4000DM000 1F2168 CC52> at ata2-master UDMA100 SATA
ad5: 3815447MB <ST4000DM000 1F2168 CC52> at ata2-slave UDMA100 SATA
ad6: 3815447MB <ST4000DM000 1F2168 CC52> at ata3-master UDMA100 SATA
ad7: 3815447MB <ST4000DM000 1F2168 CC52> at ata3-slave UDMA100 SATA

NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT
z 14.6T 10.1T 4.50T 69% 1.00x ONLINE -

scan: scrub repaired 43K in 25h15m with 0 errors <--

NAME STATE READ WRITE CKSUM
z ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
ad6 ONLINE 0 0 0
ad4 ONLINE 0 0 0
ad5 ONLINE 0 0 0
ad7 ONLINE 0 0 0

-andyf