Hello,
I’m currently performing a ZFS expand on a RAIDZ1 pool. It is moving at a snails pace over the past day since starting:
[~]$ sudo zpool status media
pool: media
state: ONLINE
scan: scrub repaired 0B in 02:26:30 with 0 errors on Sun Mar 1 02:26:31 2026
expand: expansion of raidz1-0 in progress since Mon Mar 9 16:07:20 2026
1012G / 4.32T copied at 9.98M/s, 22.86% done, 4 days 01:20:47 to go
config:
NAME STATE READ WRITE CKSUM
media ONLINE 0 0 0
raidz1-0 ONLINE 0 0 0
0a8b18e7-d8b9-41f2-9de1-a8750aa6fd8f ONLINE 0 0 0
3999e64b-a0ac-40ed-b872-d04f69cc1a1c ONLINE 0 0 0
3679901a-077a-4233-ae1f-11380b7a6e6f ONLINE 0 0 0
f7445afc-2562-460a-907c-5884e9a1203e ONLINE 0 0 0
errors: No known data errors
I’ve been searching around and found a few other posts with similar issues. A common check is to verify that write-caching is enabled for all drives in the pool. Turns out one of my drives has this disabled:
[~]$ for disk in /dev/sd?; do;sudo hdparm -W $disk; done
/dev/sda:
write-caching = 1 (on)
/dev/sdb:
write-caching = 1 (on)
/dev/sdc:
write-caching = 1 (on)
/dev/sdd:
write-caching = 1 (on)
/dev/sde:
write-caching = 1 (on)
/dev/sdf:
write-caching = 1 (on)
/dev/sdg:
write-caching = 1 (on)
/dev/sdh:
write-caching = 1 (on)
/dev/sdi:
write-caching = 0 (off)
I’ve tried forcing write-caching with the hdparm command with no luck:
[~]$ sudo hdparm -W 1 /dev/sdi
/dev/sdi:
setting drive write-caching to 1 (on)
write-caching = 0 (off)
Even after rebooting this bit was stuck to 0 for the same drive.
What steps should I take next to enable write caching on this drive?
Not finding a whole lot of info where to look next to enable write-caching. The odd thing is that sda, sdb, and sdi are all the same exact HDD model. sda, sdb, and sdi are connected through my HBA but sdi is connect to my MOBOs chipset. Other drives that are connected to my motherboard have write-caching enabled though. Is it how sdi is connected to my system?
Honestly not a dealbreaker that this expand will take a few days. Mostly curious why write-caching is disabled on one drive and how that might impact performance elsewhere on my system.
Thanks in advance!
Some system information along with commonly requested shell outputs are included in this section.
System Specs
- OS Version: TrueNAS-SCALE-24.10.2.2
- Motherboard: ASUS-ROG-MAXIMUS-IX-CODE Z270
- CPU: Intel(R) Core™ i7-7700K CPU @ 4.20GHz
- HBA: IBM M1115 LSI 9223-8i
Drive Models
sda- MB2000GCEHKsdb- MB2000GCEHKsde- WDC_WD2002FYPS-18U1B0 (new drive)sdi- MB2000GCEHK
Note:sda,sdb, andsdiare connected to my HBA.sdiis connect to my MOBOs chipset.
zpool iostat media -v
[~]$ sudo zpool iostat media -v
capacity operations bandwidth
pool alloc free read write read write
---------------------------------------- ----- ----- ----- ----- ----- -----
media 4.32T 1.13T 245 1.51K 15.8M 15.7M
raidz1-0 4.32T 1.13T 245 1.51K 15.8M 15.7M
0a8b18e7-d8b9-41f2-9de1-a8750aa6fd8f - - 123 427 5.26M 3.93M
3999e64b-a0ac-40ed-b872-d04f69cc1a1c - - 115 426 5.26M 3.93M
3679901a-077a-4233-ae1f-11380b7a6e6f - - 5 147 5.26M 3.93M
f7445afc-2562-460a-907c-5884e9a1203e - - 0 543 56 3.93M
---------------------------------------- ----- ----- ----- ----- ----- -----
iostat -x
Linux 6.6.44-production+truenas (irvingnas) 03/10/26 _x86_64_ (8 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
2.66 0.11 4.33 12.20 0.00 80.69
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
loop0 0.19 3.54 0.00 0.00 0.08 18.23 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
loop1 0.00 0.01 0.00 0.00 0.03 18.56 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 127.41 4126.07 0.05 0.04 7.47 32.38 431.34 3075.59 0.01 0.00 1.05 7.13 0.00 0.00 0.00 0.00 0.00 0.00 0.03 39.38 1.41 64.72
sdb 118.89 4126.18 0.04 0.04 8.07 34.71 429.88 3075.56 0.02 0.01 1.18 7.15 0.00 0.00 0.00 0.00 0.00 0.00 0.03 42.02 1.47 68.46
sdc 0.09 7.26 0.00 0.01 2.78 76.63 0.91 7.70 0.00 0.26 0.73 8.48 0.00 0.00 0.00 0.00 0.00 0.00 0.03 18.90 0.00 0.07
sdd 0.08 7.35 0.00 0.01 3.68 87.45 0.91 7.69 0.00 0.25 0.70 8.49 0.00 0.00 0.00 0.00 0.00 0.00 0.03 18.69 0.00 0.07
sde 0.02 0.58 0.00 0.00 14.88 32.24 516.01 3073.41 0.02 0.00 0.29 5.96 0.00 0.00 0.00 0.00 0.00 0.00 0.03 25.45 0.15 7.24
sdf 1.05 77.30 0.00 0.04 0.51 73.65 8.01 125.15 0.04 0.55 0.17 15.63 0.00 0.00 0.00 0.00 0.00 0.00 0.27 1.30 0.00 0.10
sdg 0.09 7.15 0.00 0.03 3.23 81.60 0.91 7.70 0.00 0.26 0.71 8.49 0.00 0.00 0.00 0.00 0.00 0.00 0.03 18.71 0.00 0.07
sdh 0.76 18.61 0.00 0.17 0.71 24.41 23.90 457.26 0.15 0.63 3.39 19.13 0.00 0.00 0.00 0.00 0.00 0.00 1.28 9.03 0.09 1.96
sdi 8.41 4123.97 0.00 0.00 14.88 490.50 151.13 3073.83 0.00 0.00 13.07 20.34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.10 98.56