[ceph-users] how to test journal?

Loris Cuoghi loris.cuoghi at artificiale.net
Tue Nov 21 01:26:53 PST 2017


Le Tue, 21 Nov 2017 10:52:43 +0200,
Rudi Ahlers <rudiahlers at gmail.com> a écrit :

> [snip, snap]
> 
> Maybe I'm confusing the terminology. I have created a DB and WAL
> device for my Bluestore, but I presume that's not a journal
> (anymore?).

They never were, please read further in the documentation and mailing
list archives about their respective functions. For instance:
http://docs.ceph.com/docs/master/rados/configuration/bluestore-config-ref/

> 
> This is how I set it up this time: ceph-disk prepare
> --bluestore /dev/sdc --block.wal /dev/sde --block.db /dev/sde

Putting the WAL and DB on the same device is a non sequitur once you
carefully read the available documentation and ML. The whole purpose of
a WAL is in it being on a faster device than the DB/main storage one(s).

> 
> Apart from "ceph grafana", which I can't install at this stage since
> the cluster isn't ready yet, how else can I test the SSD cache drives?
> 
> On Tue, Nov 21, 2017 at 10:37 AM, Christian Balzer <chibi at gol.com>
> wrote:
> 
> > On Tue, 21 Nov 2017 10:23:20 +0200 Rudi Ahlers wrote:
> >  
> > > Hi,
> > >
> > > Is it possible to test the CEPH journal to see if it performs
> > > optimally? 
> > You're using bluestore, as I said before, there is no journal.
> >
> > The SSDs you're using are top of the line, perfectly suited for what
> > you're using them for.
> >  
> > > And, how can I see how much data is being cached?
> > >  
> > Nothing gets cached per se with bluestore.
> > As for utilization, there were values for the journal, AFAIK there
> > isn't anything for the DB stuff at this point.
> >
> > In general, google "ceph grafana", you will REALLY want to monitor
> > a ceph cluster this way.
> >
> > --
> > Christian Balzer        Network/Systems Engineer
> > chibi at gol.com           Rakuten Communications
> >  
> 
> 
> 



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