Hi Gareth,
- Smartmon/smarctl does not report any hw issues on the HDDs.
- Fragmentation score is 1 (not fragmented at all)
- 18% used only
- RAID status is green (force-resynced)
- rebooted several times
- the IO utilization is almost zero(!) - chart attached
- tried to change the io scheduler of the disks from mq-deadline to noop:
does not bring change.
- the read latency increased on ALL 4 discs by the bullseye upgrade!
- no errors/warnings in kern.log/syslog/messages
Br,
Mihaly
On Tue 8 Nov 2022, at 09:48, Vukovics Mihály <v...@informatik.hu> wrote:
Hello Community,
since I have upgraded my debian 10 to 11, the read IO wait time of all
disks have been increased dramatically.
[...]
Chart attached, you can clearly see the date of the upgrade.
Any ideas?
Hello,
I'm not an expert in the area, but a few thoughts:
---
(Seemingly unlikely issues)
Hardware problems coincident with upgrade - smartmon tests?
Fragmentation? What % capacity is used? What filesystem?
---
RAID status?
Have you rebooted?
After a quick web search, this article suggests iowait may not be the best
indicator of problems (though not sure if this extends to wait times for
particular operations)...
https://ioflood.com/blog/2021/01/25/iowait-in-linux-is-iowait-too-high/
...does iostat's %util give cause for concern? (per the article)
HDDs or SSDs? The article suggests ~100ms may be reasonble for HDDs - your
chart only seems to show one outstandingly high wait time - do you actually
notice a difference in performance?
Not sure if any of that helps but I will follow the thread with interest.
Nice chart btw. What produced the data and the chart itself?
Best wishes,
Gareth
--
Köszönettel:
Vukovics Mihály