Some new information:
It looks like the hang happens at the 4194304 byte boundary.
For example:
`dd if=/dev/zero of=zero bs=4194304 count=1` succeeds, but
`dd if=/dev/zero of=zero bs=4194305 count=1` hangs with an
empty file.
If bs is set lower, e.g. 8192, then 4194304 bytes are
written to a file and then the hang happens. The problem is
transient. Sometimes it goes away sometimes it comes back.
Tested on 3.10.0-1160.62.1.el7 kernel.
I've resolved slow metadata io issues and metadata is now
stored on 12 NVMe flash OSDs, so that wasn't the cause.
Vlad
On 4/24/22 16:25, Vladimir Brik wrote:
Hello
We are experiencing an issue where, sometimes, when users
write to cephfs an empty file is created and then the
application hangs, seemingly indefinitely. I am sometimes
able to reproduce with dd.
Does anybody know what might be going on?
Some details:
- ceph health complains about 100+ slow metadata IOs
- CPU utilization of ceph-mds is low
- We have almost 200 kernel cephfs clients
- Cephfs metadata is stored on 3 OSDs that use NVMe flash AICs
Vlad
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx
