Raidz1 4x4TB HDD zfs pool write speed is low (lower than 7MB/s)

[Davvo]

I don't see anything unusual in the iostat screenshot... besides the sdj and sdk (which I assume are the SSDs) discrepancy.

 

[Proxy5]

I don't see anything unusual in the iostat screenshot... besides the sdj and sdk (which I assume are the SSDs) discrepancy.

Unfortunately, neither do I, only that the combined writing speed of the four discs does not even reach 7000kb/s. :(

yes the sdj and sdk devices are SSDs the zfs pool called Apps

Thank you too for following this tangled thread.

 

[HoneyBadger]

Hey HoneyBadger

I will try to answer the questions asked accurately.


View attachment 70575
If I understand correctly, the fragmentation is 18%.

That's correct.

View attachment 70578
The disks affected are:
sdb
sdc
sde
sdd

What's jumping out to me right away is the small wareq-sz - it appears to be only 16K average size. Compare this with my iostat below where I'm copying a multi-GB ISO, writing drives being sd[a-d]:

Code:

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           1.80    0.00    4.50    3.54    0.00   90.16

Device            r/s     rkB/s   rrqm/s  %rrqm r_await rareq-sz     w/s     wkB/s   wrqm/s  %wrqm w_await wareq-sz     d/s     dkB/s   drqm/s  %drqm d_await dareq-sz     f/s f_await  aqu-sz  %util
nvme0n1          0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00
sda              0.00      0.00     0.00   0.00    0.00     0.00   70.20  62280.00     0.00   0.00    8.85   887.18    0.00      0.00     0.00   0.00    0.00     0.00    0.40    2.50    0.62  31.36
sdb              0.00      0.00     0.00   0.00    0.00     0.00   70.00  62280.00     0.00   0.00    9.10   889.71    0.00      0.00     0.00   0.00    0.00     0.00    0.40    4.00    0.64  32.40
sdc              0.00      0.00     0.00   0.00    0.00     0.00   74.40  64265.60     0.00   0.00    8.66   863.78    0.00      0.00     0.00   0.00    0.00     0.00    0.40    5.50    0.65  32.24
sdd              0.00      0.00     0.00   0.00    0.00     0.00   75.40  64265.60     0.00   0.00    8.35   852.33    0.00      0.00     0.00   0.00    0.00     0.00    0.40    6.00    0.63  31.20
sde              0.00      0.00     0.00   0.00    0.00     0.00   24.40    140.80     0.00   0.00    0.04     5.77    0.00      0.00     0.00   0.00    0.00     0.00    1.40    0.14    0.00   0.56
sdf              0.00      0.00     0.00   0.00    0.00     0.00   25.20    136.00     0.00   0.00    0.04     5.40    0.00      0.00     0.00   0.00    0.00     0.00    1.40    0.00    0.00   0.56
sdg              0.00      0.00     0.00   0.00    0.00     0.00   24.60    138.40     0.00   0.00    0.04     5.63    0.00      0.00     0.00   0.00    0.00     0.00    1.40    0.14    0.00   0.56
sdh              0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00
sdi              0.00      0.00     0.00   0.00    0.00     0.00   23.60    136.80     0.00   0.00    0.04     5.80    0.00      0.00     0.00   0.00    0.00     0.00    1.40    0.14    0.00   0.56
sdj              0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00
sdk              0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00
sdl              0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00      0.00     0.00   0.00    0.00     0.00    0.00    0.00    0.00   0.00

zfs get recordsize please? You can paste directly here using the [CODE] format tags.

 

[Proxy5]

What's jumping out to me right away is the small wareq-sz - it appears to be only 16K average size. Compare this with my iostat below where I'm copying a multi-GB ISO, writing drives being sd[a-d]:

I can see the difference, but unfortunately I don't understand zfs so deeply anymore to know what causes it.
It's not so far-fetched that I can do anything about it, at least I think.

zfs get recordsize please? You can paste directly here using the [CODE] format tags.

Code:

root@truenas[~]# zfs get recordsize Backup
NAME    PROPERTY    VALUE    SOURCE
Backup  recordsize  128K     default

All zfs pools show the same default value of 128k