Rich Freeman on 6 Feb 2013 10:43:13 -0800

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Re: [PLUG] Solaris backup/restore

On Wed, Feb 6, 2013 at 1:18 PM, Sean M. Collins <> wrote:
> On Wed, Feb 06, 2013 at 12:14:49PM -0500, Eric Lucas wrote:
>> They suggested using dd and scripting it but I know the disks (200
>> GB) are not full so using dd seems like a crazy waste of space (DVDs full
>> of nothing.)
> I think you can just pipe dd through gzip when you're creating the backup - it'll
> compress the unused space. Then just pipe gunzip to dd to restore.

I think (but could be mistaken) that they essentially want to do the
restore while doing the backup - that is their backup is a clone of
the original drive, which means you could just swap the drive out and
power up and be running.

In that case gzip won't buy you anything - every cluster on the source
drive has to read, and every cluster on the destination drive has to
be written.  Those are the rate-limiting steps so anything you do on
the CPU in-between won't do much.

If you were storing the image files then compressing them would
obviously reduce space use, and if you could store a compressed image
instead of a live image then it would also reduce the number of blocks
to be written during the backup.

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