[TriLUG] Anyone here know much about kernel programming?

[Len Boyle]

No matter what the filesystem one does have to worry about open files and a consistent view of data. The application can have data in memory that it only writes to disk at app shutdown time. Sometimes this may require working with multiple apps across multiple systems.
Some apps have a command to generate a  consistent view on disk. 
Some apps have a command to generate a backup stream of data.
For example Oracle Rman command.

If you were using Solaris or Freebsd you could look at zfs. I am not sure if Open Solaris is still an option. One group did fork off a copy.

There is also Oracle's  btrfs. See https://btrfs.wiki.kernel.org/index.php/Main_Page



-----Original Message-----
From: trilug-bounces at trilug.org [mailto:trilug-bounces at trilug.org] On Behalf Of Igor Partola
Sent: Monday, July 11, 2011 2:16 PM
To: Triangle Linux Users Group General Discussion
Subject: Re: [TriLUG] Anyone here know much about kernel programming?

If I understand correctly, you still would need to deal with the applications that are using the file system, at least on some level. Unless all the applications involved only use atomic transactions on the file system (which is pretty rare, from what I've seen), getting a consistent snapshot will always involve shutting down/pausing some of the applications first, then taking the snapshot (through whatever means necessary) and then starting the applications back up. I think from this point of view LVM is pretty good since it only takes a few moments to create the snapshot. You could also look at rdiff and rdiff-backup for more ad-hoc setups where speed is not as much of an issue.

Igor

On Mon, Jul 11, 2011 at 2:10 PM, Paul Bennett <paul.w.bennett at gmail.com>wrote:

> On Mon, 11 Jul 2011 13:57:36 -0400, Cristóbal Palmer 
> <cmp at cmpalmer.org>
> wrote:
>
>  If you are using LVM, as you should be, it is pretty simple:
>>
>> http://tldp.org/HOWTO/LVM-**HOWTO/snapshots_backup.html<http://tldp.o
>> rg/HOWTO/LVM-HOWTO/snapshots_backup.html>
>>
>
> There's a number of different systems in play here. I'm not the 
> sysadmin for them (thank the maker), but there are some cases where we 
> have to (e.g.) take down one half of a two-node cluster for a few 
> seconds in order to make a consistent backup of the data.
>
> I'm looking for a kind of "One Ring" solution that can be dropped in 
> place for situations like this, where for whatever reason the system 
> is adminsitered in such a way as to make LVM and CLVM snapshot backups 
> tedious or difficult or annoying or something.
>
>
> Thanks,
>
>
> --
> Paul
>
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