How long is “too long”? 800MB on an SSD should only be a second or three.
I’m not sure if that’s a reasonable amount of data; you could try
compacting the rocksdb instance etc. But if reading 800MB is noticeable I
would start wondering about the quality of your disks as a journal or
rocksdb device.
-Greg

On Tue, Jun 12, 2018 at 2:23 PM Alfredo Daniel Rezinovsky <
[email protected]> wrote:

> I migrated my OSDs from filestore to bluestore.
>
> Each node now has 1 SSD with the OS and the BlockDBs and 3 HDDs with
> bluestore data.
>
> # lsblk
> NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
> sdd      8:48   0   2.7T  0 disk
> |-sdd2   8:50   0   2.7T  0 part
> `-sdd1   8:49   0   100M  0 part /var/lib/ceph/osd/ceph-2
> sdb      8:16   0   3.7T  0 disk
> |-sdb2   8:18   0   3.7T  0 part
> `-sdb1   8:17   0   100M  0 part /var/lib/ceph/osd/ceph-0
> sdc      8:32   0   3.7T  0 disk
> |-sdc2   8:34   0   3.7T  0 part
> `-sdc1   8:33   0   100M  0 part /var/lib/ceph/osd/ceph-1
> sda      8:0    0 223.6G  0 disk
> |-sda4   8:4    0     1G  0 part
> |-sda2   8:2    0  37.3G  0 part /
> |-sda5   8:5    0     1G  0 part
> |-sda3   8:3    0     1G  0 part
> `-sda1   8:1    0   953M  0 part /boot/efi
>
> Now the I/O works better, and I never saw again a slow response (OSD not
> MDS) warning.
>
> But when I reboot a ceph node the OSDs takes too long to get up. With
> filestore it was almost inmediate.
>
> Monitoring /proc/$(pidod ceph-osd)/io I could see that each OSD reads
> about 800 MBytes before getting up (My block.db partitions are 1G).
>
> Does the OSDs start re-process all the block.db when booting up?
>
> There's any way to accelerate the OSD availability after a reboot?
>
>
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>
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