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Re: Snapshots in tmpfs

On Thu, Feb 23, 2012 at 07:58:11AM +0000, David Holland wrote:
> On Wed, Feb 22, 2012 at 08:17:15AM -0600, David Young wrote:
>  > On Wed, Feb 22, 2012 at 01:42:45PM +0100, Manuel Wiesinger wrote:
>  > > *)
>  > > What is it good for? The only practical use I can imagine are
>  > > backups on thin clients, which operate without a hard disk. But this
>  > > is clearly far-fetched, in my eyes.
>  > 
>  > It's good for writing checkpoints of a tmpfs to non-volatile (NV)
>  > storage in an embedded system where writing to the NV storage is costly
>  > (it wears out, or it is slow, or both).  When you have a snapshot, you
>  > can stream it to NV storage using pax(1).  This is the best practical
>  > way that I can think of in NetBSD at this time.
> other than, say, chfs or lfs?

Is CHFS really suitable for CompactFlash?  Is LFS even usable?

> That sounds like a horrible hack, anyhow, and prone to dying horribly
> if you crash or lose power in the middle of a writeback. (plus you'd
> want to use rsync to transfer, or so I'd think, or rewriting
> unmodified blocks will burn write cycles faster than not bothering to
> do anything special.)

I agree that whatever you have in mind sounds like a horrible hack. :-)


David Young    Urbana, IL    (217) 721-9981

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