From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <4017E699.5020703@gene.concordia.ca> From: Chris Beck MIME-Version: 1.0 Subject: Re: [linux-lvm] LVM Snapshots for remote archiving. References: <4016EE45.1050300@gene.concordia.ca> <1075246162.25365.16.camel@david.internal.NorcrossGroup.com> In-Reply-To: <1075246162.25365.16.camel@david.internal.NorcrossGroup.com> Content-Transfer-Encoding: quoted-printable Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Wed Jan 28 11:44:02 2004 List-Id: Content-Type: text/plain; charset="utf-8"; format="flowed" To: linux-lvm@sistina.com I guess I am misunderstanding how a snapshot volume works, I kinda=20 thought it would be this mythical transaction log - disk writes need to=20 be stored somewhere while the original volume is frozen and I was hoping=20 that I could move the whole thing around like any other file. I was hoping to avoid rsync/rdiff because the snapshot volume itself was=20 a list of differences over the last 24 hours. It is whispered that Greg Freemyer was heard, on or about 1/27/2004 6:29=20 PM to say: >On Tue, 2004-01-27 at 18:03, Chris Beck wrote: > =20 > >>Hi! I've been looking through the archives and I can't see anything=20 >>addressing my issue. Probably because I didn't look hard enough. >> >>I want to use 24-hour snap shots as an archival tool. >>I have 2 identical file servers, one primary and one as an off-site=20 >>mirror. I'd like the primary system to generate a transaction log that= =20 >>rolls over every 24-hours and gets transmitted to the remote site. =20 >>After 7 days on the remote site, the log gets triggered so the remote i= s=20 >>always 7 days out of sync but with the last 6 days logs ready to go. = I=20 >>could have it auto update on arrival, but I was thinking that allowing = a=20 >>week for someone to realize that they deleted something vital would be = a=20 >>good thing(TM) - standard archiving stuff I guess. >> >>Do you think that lvm snapshot volumes are a simple and convenient way=20 >>of doing this? Does this make sense at all? >> >>Thanks, >>Chris >> =20 >> > >The above transaction log is new to me. I have seen that done with >databases, but not with generic fileservers. > >If I was trying to accomplish what I think are your goals, I would use >rdiff-backup. > >I don't know the syntax offhand, but the process would be: > >Create snapshot >mount snapshot as /snap >rdiff-backup /snap //backup_server/snap=20 >rdiff-backup --delete_older_than 7-days //backup_server > >rdiff-backup uses technology similar to rsync to ensure only the deltas >are sent between the servers. (ie. first check datestamps etc. to see >if file changed. If so, use md5sums to isolate what parts of the file >changed and send them between the servers.) > >It maintains a current copy of the source files, and a series of diffs >to go backwards to older versions of the files. In the above it would >keep a max of 7 diffs per file. If you wanted to restore from 7 days >prior, rdiff-backup would internally have to apply all 7 diffs, one >after another. > >rdiff-backup has lots of other features/capabilities. > >Also, it uses ssh to encrypt all data between the servers, so it is also >fairly secure. > >The only problems I have with rdiff-backup are: > >1) ACL and EA support is only in the Unstable release, but they seem to >be working fine > >2) rdiff-backup is written in python and when an unhandled error occurs, >it dumps out a stack trace. To see what the problem is you have to go >thru the stack trace and the code. Not to bad if you have some >programming skills. If not, the mailing list is fairly responsive. > >There is a wiki at >http://rdiff-backup.solutionsfirst.com.au/index.php?RdiffBackupWiki > >Greg > =20 > --=20 Chris Beck / Y.A.B.A. / Fungal Genomics CFSG / Concordia University "La loi dans sa majestueuse =C3=A9galit=C3=A9, interdit =C3=A0 tous, aux = riches comme aux pauvres de dormir sous les ponts, de coucher dans la rue et de voler du pain." -- Anatole France (Les Lys Rouge - 1894)