[ale] Question: to LVM or not LVM

[Greg Freemyer]

Mike,

I've seen a couple filesystems with the snapshot feature.  Win2003 even went
that way with NTFS I believe.

Need I say more. :)

Seriously you can add a significant number of lines code to each and every
filesystem, or you can put a LVM layer below the filesystem and implement it
there.  Then you just need a much smaller amount of interface code to let a
filesystem take advantage of the underlying snapshot code.

Since Linux supports a fairly large number of different filesystems, they
chose to go the LVM route.  Another nice feature is that from a filesystem
perspective supporting a snapshot capable LVM is very similar to supporting
a snapshot capable array.  (Think SAN.)

Greg

On 2/11/07, Michael B. Trausch <fd0man at gmail.com> wrote:
>
>  On Sat, 2007-02-10 at 19:08 -0500, Greg Freemyer wrote:
>
> First, I would never boot dom0 off of LVM.  If you have a problem itmakes it hard to fix.
> Other than that LVM is a good fit with any VM if you are going tocreating / deleting VM setups.  OTOH, if it is a one time thing youdon't need it.
> There are 2 big advantages to LVM; flexibility and snapshots.
>
>
> Is there any particular reason that LVM is required for FS snapshotting
> under Linux?  My understanding of FreeBSD is that you can snapshot UFS2
> drives in a regular partition, and that happens at the FS level.  Why didn't
> Linux go that route?
>
>     -- Mike
>
> --
>   Michael B. Trausch  fd0man at gmail.com
>   Phone: (404) 592-5746   Jabber IM:  fd0man at gmail.com
> fd0man at livejournal.com
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-- 
Greg Freemyer
The Norcross Group
Forensics for the 21st Century
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