Re: BlueStore fragmentation woes

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

 



On 5/25/23 18:17, Igor Fedotov wrote:
Perhaps...

I don't like the idea to use fragmentation score as a real index. IMO it's mostly like a very imprecise first turn marker to alert that something might be wrong. But not a real quantitative high-quality estimate.

Chiming in on the high fragmentation issue. We started collecting "fragmentation_rating" of each OSD this afternoon. All OSDs that have been provisioned a year ago have a fragmentation rating of ~ 0.9. Not sure for how long they are on this level. And after reading your mails it might not be a problem at all. But we will start collecting this information in the coming weeks.

We will be re-provisioning all our OSDs, so that might be a good time to look at the behavior and development of "cnt versus frags" ratio.

After we completely emptied a host, even after having the OSDs run idle for a couple of hours, the fragmentation ratio would not drop lower than 0.27 for some OSDs, and up to 0.62 for others. Is it expected that this will not go to ~ zero?

We have not noticed any performance degradation whatsoever. We are running with bitmap for current OSDs, hybrid allocator for the new provisioned OSDs (4k min alloc size).

Gr. Stefan
_______________________________________________
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