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Re: Optimal configuration of Xiotech Magnitude for RMAN backups

From: Jeffery Thomas <>
Date: Thu, 9 Nov 2006 07:36:56 -0500
Message-ID: <>

We do have tape drives, unfortunately, the transfer rate is topping around around 7Mb/sec and I've given up on it because it was taking 20+ hours to backup the database.

On 11/8/06, Mark Brinsmead <> wrote:
> At one site I used to be at, there was a "storage manager" who swore that
> XIOtech disk arrays were the greatest thing since sliced bread becausethey have no cache. I never quite figured that out... ;-)
> If you insist on using this device, and you've already determined that
> RAID-5 sucks, I would think you choices are rather limited...
> It tops out at 75MB/s, huh? Here's a wild idea: have you considered a tape
> drive? I know this is kinda off the wall, radical sort of stuff, but hey,
> it may be worth a look. ;-)
> I haven't shopped for tape drives lately, but my very first (and
> completely arbitrary) peek at the internet turned up an Exabyte Magnum LTO-3
> tape drive. According to the datasheet, it does 160MB/s (assuming 2:1
> compression), stores 800GB on one cartridge (again 2:1 compression), and
> costs about USD $6500. Add a few hundred bucks for a dedicated LVD SCSI
> controller, and that's still probably less than you'll spend to maintain
> that XIOtech for a year.
> And just for good measure -- the tape drive has more cache than the
> XIOtech! Not that this is a challenge. ;-) (128MB on the LTO-3 model)
> The numbers above are based on the manufacturer's datasheet, which you can
> find here:
> (Reading the last page of the sheet, I get the impression that the
> transfer rates mentioned on the first page -- the ones I quoted above -- are
> "burst" rates. The sustained I/O rates are a good bit slower, but this
> puppy should still blow the doors off your XIOtech...)
> Note: everything above -- aside from the "dinosaur" technical advice --
> is taken from the vendors website, and the result only about about 30
> seconds inspection. I've offered it for illustration only. Read it for
> yourself, just in case I have misread/misinterpreted something.
> If you still want to use that fancy-schmancy XIOtech for a "sexy"
> disk-to-disk backup solution, I'd suggest you use either RAID-0 or RAID-10,
> depending on your capacity requirements.
> On 11/8/06, Jeffery Thomas <> wrote:
> >
> > Goran,
> >
> > That's is a big problem with this array, we do not have *any* cache :(
> >
> > We tried RAID5 and performance was horrendous.
> > ...
> >
> --
> Cheers,
> -- Mark Brinsmead
> Senior DBA,
> The Pythian Group

Received on Thu Nov 09 2006 - 06:36:56 CST

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