Re: Bluestore cluster example

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On Fri, 22 Apr 2016, Dan van der Ster wrote:
> Hi Mark,
> 
> On Fri, Apr 15, 2016 at 2:06 PM, Mark Nelson <mnelson@xxxxxxxxxx> wrote:
> > Hi all,
> >
> > A couple of folks have asked me how to setup bluestore clusters for
> > performance testing.  I personally am using cbt for this, but you should be
> > able to use ceph-disk with some other cluster creation method as well.
> >
> > For CBT, you really don't need to do much.  In the old newstore days, a
> > "block" symlink needed to be created in the osd data dir to link to the new
> > block device.  CBT did this when the "newstore_block: True" option was set
> > in the cluster section of the cbt yaml file.  This isn't really needed
> > anymore, as you can now specify the block, db, and wal devices directly in
> > your ceph.conf file.  If your partitions are setup properly you can create
> > bluestore clusters without having to do anything beyond changing the
> > ceph.conf file (with cbt at least).
> >
> > Here's a very basic example:
> >
> > [global]
> >         enable experimental unrecoverable data corrupting features =
> > bluestore rocksdb
> >         osd objectstore = bluestore
> >
> > [osd.0]
> >         host = incerta01.front.sepia.ceph.com
> >         osd data = /tmp/cbt/mnt/osd-device-0-data
> >         bluestore block path = /dev/disk/by-partlabel/osd-device-0-block
> >         bluestore block db path = /dev/disk/by-partlabel/osd-device-0-db
> >         bluestore block wal path = /dev/disk/by-partlabel/osd-device-0-wal
> 
> The db and wal paths are optional perf boosting things, right?

Yeah.
 
> If I do ceph-disk prepare --bluestore /dev/sdae, I get:
> 
> /dev/sdae :
>  /dev/sdae2 ceph block, for /dev/sdae1
>  /dev/sdae1 ceph data, active, cluster ceph, osd.413, block /dev/sdae2

Looks right!  ceph-disk isn't smart enough to set up the wal or db devices 
yet.

The wal device should default to something like 128 MB.

The db device would be whatever portion of an SSD you want to allocate to 
storing the bluestore metadata.  My guess is that we'll get further than 
we did with FileStore, so the old 1:4 or 1:5 rule of thumb might be more 
like 1:10, but who knows--this'll require some testing.

sage

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