[ceph-users] How to set osd_max_backfills in Luminous

Jean-Charles Lopez jelopez at redhat.com
Tue Nov 21 16:14:56 PST 2017


Hi,

to check a current value use the following command on the machine where the OSD you want to check is running

ceph daemon osd.{id} config show | grep {parameter}
  Or
ceph daemon osd.{id} config get {parameter}

What you are seeing is actually a known glitch where you are being told it has no effect when in fact it does. See capture below
[root at luminous ceph-deploy]# ceph daemon osd.0 config get osd_max_backfills
{
    "osd_max_backfills": "1"
}
[root at luminous ceph-deploy]# ceph tell osd.* injectargs '--osd_max_backfills 2'
osd.0: osd_max_backfills = '2' rocksdb_separate_wal_dir = 'false' (not observed, change may require restart)
osd.1: osd_max_backfills = '2' rocksdb_separate_wal_dir = 'false' (not observed, change may require restart)
osd.2: osd_max_backfills = '2' rocksdb_separate_wal_dir = 'false' (not observed, change may require restart)
[root at luminous ceph-deploy]# ceph daemon osd.0 config get osd_max_backfills
{
    "osd_max_backfills": "2"
}

Regards
JC

> On Nov 21, 2017, at 15:17, Karun Josy <karunjosy1 at gmail.com> wrote:
> 
> Hello,
> 
> We added couple of OSDs to the cluster and the recovery is taking much time.
> 
> So I tried to increase the osd_max_backfills value dynamically. But its saying the change may need restart. 
> 
> $ ceph tell osd.* injectargs '--osd-max-backfills 5'
> osd.0: osd_max_backfills = '5' osd_objectstore = 'bluestore' (not observed, change may require restart) rocksdb_separate_wal_dir = 'false' (not observed, change may require restart)
> ------------
> ------------
> =============
> 
> The value seems to be not changed too.
> 
> [cephuser at ceph-las-admin-a1 home]$  ceph -n osd.0 --show-config | grep osd_max_backfills
> osd_max_backfills = 1
> 
> Do I have to really restart all the OSD daemons ?
> 
> 
> 
> Karun 
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