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From: Gandalf Corvotempesta <gandalf.corvotempesta@gmail.com>
To: Tren Blackburn <tren@eotnetworks.com>
Cc: ceph-devel@vger.kernel.org
Subject: Re: Ceph journal
Date: Wed, 31 Oct 2012 22:58:31 +0100	[thread overview]
Message-ID: <CAJH6TXjGP5QqOWchRTwUQ-EigCU9qAORA87JrZ6bhG5J4im=-A@mail.gmail.com> (raw)
In-Reply-To: <CANLRBoyLHrLP_hg6DSbESk=JhfHa5rzHiyLHcAotUokRe--xVA@mail.gmail.com>

2012/10/31 Tren Blackburn <tren@eotnetworks.com>:
> Unless you're using btrfs which writes to the journal and osd fs
> concurrently, if you lose the journal device (such as due to a
> reboot), you've lost the osd device, requiring it to be remade and
> re-added.

I don't understood.
Loosing a journal, will result in the whole OSD lost?

AFAIK, Ceph will write to journal. After this write it will return an "OK".
After that, the journal is wrote (in background) to a disk, so,
loosing a journal should result in loosing that portion of data, not
the whole osd.

Now, in case of 3 replicated nodes, ceph will write the same data at
the same time to the three journals? If yes, loosing a single
journal/osd should not result in loss of data, because the same data
are still on other 2 nodes. In this case, should be possible to use a
tmpfs as journal and using the replica as redundancy.

  parent reply	other threads:[~2012-10-31 21:58 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-10-31 21:18 Ceph journal Gandalf Corvotempesta
2012-10-31 21:24 ` Tren Blackburn
2012-10-31 21:32   ` Stefan Kleijkers
2012-10-31 21:54   ` Sage Weil
2012-10-31 21:58   ` Gandalf Corvotempesta [this message]
2012-10-31 22:04     ` Stefan Kleijkers
2012-10-31 22:07       ` Gandalf Corvotempesta
2012-10-31 22:55         ` Sébastien Han
2012-11-01 21:18       ` Gandalf Corvotempesta
2012-11-01 21:27         ` Mark Nelson
2012-11-01 21:33           ` Gandalf Corvotempesta
2012-11-03 17:29             ` Gregory Farnum
2012-11-04 11:48               ` Gandalf Corvotempesta
2012-11-05 13:06               ` Jean-Daniel BUSSY

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