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From Dusty Doris <couchdb.l...@dusty.name>
Subject Re: couch behavior for san snapshots
Date Tue, 20 Oct 2009 03:35:42 GMT
On Mon, Oct 19, 2009 at 5:37 PM, Alex P <apedenko@kolosy.com> wrote:
> thanks! i'll definitely look into that.

If your are using ext3 I can also help you with that.  You need to use
LVM2 to create volumes and then you can do something like

$ dmsetup suspend /dev/ebs/couchvol0
$ ebs_snapshot
$ dmsetup resume /dev/ebs/couchvol0

If you'd like more info on that let me know and I'll add some more details.



>
> On Mon, Oct 19, 2009 at 4:32 PM, Glenn Rempe <glenn@rempe.us> wrote:
>
>> Not sure if this will help at all, but I am also using EBS to store a large
>> cdb DB.
>> It is recommended that the filesystem that you want to snapshot on EBS is
>> frozen (or unmounted) if that is possible to help ensure a coherent EBS
>> snapshot.
>>
>> For example, on my mysql and couchdb volumes I use the XFS filesystem which
>> has an XFS freeze command which I use to temporarily lock the FS and flush
>> it to disk, and then request the snapshot.  You can do this in a script and
>> it takes only a few seconds of disk downtime.  I believe writes are cached
>> during this period.  I have been using this with mysql but have not yet set
>> it up for my couchdb volume.
>>
>> See :
>>
>>
>> http://developer.amazonwebservices.com/connect/entry.jspa?categoryID=100&externalID=1663
>> http://alestic.com/2009/09/ec2-consistent-snapshot
>>
>> HTH
>>
>> On Mon, Oct 19, 2009 at 1:55 PM, Chris Anderson <jchris@apache.org> wrote:
>>
>> > On Mon, Oct 19, 2009 at 12:53 PM, Alex P <apedenko@kolosy.com> wrote:
>> > > a simple copy seems to work just fine. db shows up with the right seq
>> > number
>> > > etc.
>> >
>> > cool. totally wanna learn about the SAN roundtrip. :)
>> >
>> > >
>> > > On Mon, Oct 19, 2009 at 2:37 PM, Paul Davis <
>> paul.joseph.davis@gmail.com
>> > >wrote:
>> > >
>> > >> On Mon, Oct 19, 2009 at 3:35 PM, Alex P <apedenko@kolosy.com>
wrote:
>> > >> > cdb catalogs databases purely on file name and presence in the
>> > >> appropriate
>> > >> > directory, right? so if i copy db1 to db1_copy, i should see
>> db1_copy
>> > >> show
>> > >> > up in futon?
>> > >>
>> > >> Yepper. Make sure the permissions are correct after copying though.
>> > >>
>> > >> Paul Davis
>> > >>
>> > >
>> >
>> >
>> >
>> > --
>> > Chris Anderson
>> > http://jchrisa.net
>> > http://couch.io
>> >
>>
>>
>>
>> --
>> Glenn Rempe
>>
>> email                 : glenn@rempe.us
>> voice                 : (415) 894-5366 or (415)-89G-LENN
>> twitter                : @grempe
>> contact info        : http://www.rempe.us/contact.html
>> pgp                    : http://www.rempe.us/gnupg.txt
>>
>

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