Re: Compressed Disks

There is a big difference between saving backup copies of volumes in
compressed format that compressed versions of the production drives.
For backups under Flex-ES, one need only run othe ckdbackup utility
piped to gzip to get the equivalent (or better) footprint as you
presently use for your 4 backup copies.   These copies need not be
stored on the main server, and in fact off-site is something that seems
prudent for backup copies.  In my own system here at home, I have cheap
IDE disk NSF mounted to my server which I use as a landing pad for
backups, and then copy those disks over the net to an offsite location
-- only my production disks are under the mainframe RAID array.

We don't require production to have mirroring or raid 5, but we think
one is ordinarily nuts to run production without one of these, and I
imagine the support arrangement with the reseller would reflect the lack
of what is essentially an in-place work-around to disk failure.

The statements "Compressed data can be read quicker than uncompressed
data.  I/O contention can be less." is not our usual experience, but
yours may reflect some design differences.

PDW

somitcw wrote:

>  --- In [email protected], "Peter D. Ward" <pdw@m...> wrote:
> - - -
> >We long ago rejected compressed DASD as unsuitable
> >for our production goals.  On developer systems it
> >makes more sense but there are still opportunities
> >for trouble with it.
>
>     I now keep four copies of my production system
> on one 160GB PC disk in CCKD format. ( Four weekly
> backups).  The last 160GB hard drive that I bought
> was USD150.  My small old 233Mhz and 300Mhz
> Gateway towers will hold over a TB of storage each.
> Mirror or RAID 5 would cut into that.  With RAID 5,
> I could still squeeze a TB in the little tower and
> keep about 30 copies of all of my large server disks.
> Compressed data can be read quicker than uncompressed
> data.  I/O contention can be less.
>
>     Looking at Flex-ES, I will need ten 72GB hard
> drives to hold one copy of my data which will max
> out the Flex box.  I cannot use fast ( 15K RPM )
> disks internally and still hold all of my data.
> If I need more space for faketape or other stuff,
> external disks will be needed.  The ten hard drives
> cost over USD7000.  Having to spread the data over
> so many disks does help make up for performance
> lost by not being to use compression.
>
>     If Flex coders cannot handle compressed disks,
> is there some SCO compression that works like
> Windows folder compression?  My preference would
> be a good, fast RVA emulation with the code to
> create snapshot images of my disks.
>


[Non-text portions of this message have been removed]


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