[nflug] backups on an nfs server

[Mark Musone]

FYI,

Don't get me wrong, i'm a dump/restore lover myself, and until last week swore up and down that it's stil lthe best thing since sliced bread..

HOWEVER..the following has gotten me seriously thinking otherwise..(you can google more info about it too..soem more recent)



http://lwn.net/2001/0503/a/lt-dump.php3

From:	 Linus Torvalds <torvalds at transmeta.com>
To:	 Neil Conway <nconway.list at ukaea.org.uk>
Subject: Re: [PATCH] SMP race in ext2 - metadata corruption.
Date:	 Fri, 27 Apr 2001 09:59:46 -0700 (PDT)
Cc:	 Kernel Mailing List <linux-kernel at vger.kernel.org>


[ linux-kernel added back as a cc ]

On Fri, 27 Apr 2001, Neil Conway wrote:
> 
> I'm surprised that dump is deprecated (by you at least ;-)).  What to
> use instead for backups on machines that can't umount disks regularly? 

Note that dump simply won't work reliably at all even in 2.4.x: the buffer
cache and the page cache (where all the actual data is) are not
coherent. This is only going to get even worse in 2.5.x, when the
directories are moved into the page cache as well.

So anybody who depends on "dump" getting backups right is already playing
russian rulette with their backups.  It's not at all guaranteed to get the
right results - you may end up having stale data in the buffer cache that
ends up being "backed up".

Dump was a stupid program in the first place. Leave it behind.

> I've always thought "tar" was a bit undesirable (updates atimes or
> ctimes for example).

Right now, the cpio/tar/xxx solutions are definitely the best ones, and
will work on multiple filesystems (another limitation of "dump"). Whatever
problems they have, they are still better than the _guaranteed_(*)  data
corruptions of "dump".

However, it may be that in the long run it would be advantageous to have a
"filesystem maintenance interface" for doing things like backups and
defragmentation..

		Linus

(*) Dump may work fine for you a thousand times. But it _will_ fail under
the right circumstances. And there is nothing you can do about it.




On Thu, Aug 03, 2006 at 06:47:19PM -0400, Cyber Source wrote:
> eric wrote:
> >which would be better with a mounted nfs share from a nfs server.
> >
> >executing a tar and gzip command to package a home dir on the servers
> >share from the client or
> >executing a tar and gzip command to package a home dir on the client and
> >then moving the package to the servers share?
> >
> >
> >I will want to increment files once a full backup is created, so I'm not
> >sure which would be better in the long run.
> >What seems to be quicker is to execute the increment on the share across
> >the network instead of always moving/coping a large package from client
> >to server.
> >
> >Thank you for your input,
> >Eric
> >
> >
> >
> >
> >_______________________________________________
> >nflug mailing list
> >nflug at nflug.org
> >http://www.nflug.org/mailman/listinfo/nflug
> >
> >  
> Gotta LOVE NFS!
> Here is what we do, and it works very well for us. We have a backup 
> server that has some drives lvm'd together so we have huge storage 
> capability. Then we have our boxes in the shop mount the respective 
> shares exported from the backup server, and inside those respective 
> shares are daily folders, so each box in the shop mounts it's respective 
> share from the backup server and they then all have say /backup/Monday, 
> /backup/Tuesday etc..
> I then run crons on the respective boxes to backup to that share nightly 
> of what is important on that box and to each daily folder for it's 
> respective day, as the days repeat, they get overwritten, so this gives 
> me 7 days of redundancy. I like that alot better than worrying about 
> incremental backups, etc., and hard drive space is cheap today. So on my 
> servers per say, I backup /etc /home and /var and have full dumps 
> elsewhere in case of emergency for the rest.
> I use dump to backup to these shares. I LOVE dump and it's counterpart 
> restore. Restore has an interactive flag (-i) that lets you cruise 
> through the dumps and find the data you might need, in the same 
> directory tree that it backed up. I also limit my dumps to 1gb each, 
> then they make another dump001, dump002, and the restore command can 
> parse them all with one command.
> The only thing that might stop someone from doing it this way is if they 
> actually use acl's, as dump does not do acl's. Other than that, it works 
> beautifully.
> 
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