Thank you Eric. That 'sounds like' exactly my issue. Though I'm surprised to
bump into something like that on such a small system and at such low bandwidth.
But the information I can find on those parameters is sketchy to say the least.
Can you point me at some doco that explains what they do, how to read the current values
and how to set them?
Cheers,
Steve
-----Original Message-----
From: Eric Smith <Eric.Smith(a)vecima.com>
Sent: Monday, 11 May 2020 8:00 PM
To: Steve Hughes <steveh(a)scalar.com.au>au>; ceph-users(a)ceph.io
Subject: RE: [ceph-users] Re: Write Caching to hot tier not working as expected
It sounds like you might be bumping up against the default objecter_inflight_ops (1024)
and/or objecter_inflight_op_bytes (100MB).
-----Original Message-----
From: steveh(a)scalar.com.au <steveh(a)scalar.com.au>
Sent: Monday, May 11, 2020 5:48 AM
To: ceph-users(a)ceph.io
Subject: [ceph-users] Re: Write Caching to hot tier not working as expected
Interestingly, I have found that if I limit the rate at which data is written the tiering
behaves as expected.
I'm using a robocopy job from a Windows VM to copy large files from my existing
storage array to a test Ceph volume. By using the /IPG parameter I can roughly control
the rate at which data is written.
I've found that if I limit the write rate to around 30MBytes/sec the data all goes to
the hot tier, zero data goes to the HDD tier, and the observed write latency is about
5msec. If I go any higher than this I see data being written to the HDDs and the
observed write latency goes way up.
_______________________________________________
ceph-users mailing list -- ceph-users(a)ceph.io To unsubscribe send an email to
ceph-users-leave(a)ceph.io
--
Show replies by date