On 2021/3/2 下午4:49, James Page wrote:
Hi Norman
On Mon, Mar 1, 2021 at 4:38 AM Norman.Kern <norman.kern@gmx.com> wrote:
Hi, guys
I am testing ceph on bcache devices, I found the performance is not good as expected. Does anyone have any best practices for it? Thanks.
I've used bcache quite a bit with Ceph with the following configuration options tweaked
a) use writeback mode rather than writethrough (which is the default)
This ensures that the cache device is actually used for write caching
b) turn off the sequential cutoff
sequential_cutoff = 0
This means that sequential writes will also always go to the cache device rather than the backing device
c) disable the congestion read and write thresholds
congested_read_threshold_us = congested_write_threshold_us = 0
The following repository:
https://git.launchpad.net/charm-bcache-tuning/tree/src/files
has a python script and systemd configuration todo b) and c) automatically on all bcache devices on boot; a) we let the provisioning system take care of.
HTH
I have set the variables described above. Didn't you met the latency problems when cache used increaced 30%? My cache status like this: root@WXS0089:~# cat /sys/block/sda/bcache/priority_stats Unused: 4% Clean: 28% Dirty: 70% Metadata: 0% Average: 551 Sectors per Q: 29197312 Quantiles: [27 135 167 199 230 262 294 326 358 390 422 454 486 517 549 581 613 645 677 709 741 773 804 836 844 847 851 855 860 868 881]
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io
_______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-leave@ceph.io