Re: Best practices for OSD on bcache

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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@xxxxxxx> 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@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
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx




[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]


  Powered by Linux