ADSM-L

Re: [ADSM-L] Raid 1 vs Raid 5

2010-08-09 12:40:35
Subject: Re: [ADSM-L] Raid 1 vs Raid 5
From: "Ochs, Duane" <Duane.Ochs AT QG DOT COM>
To: ADSM-L AT VM.MARIST DOT EDU
Date: Mon, 9 Aug 2010 11:37:04 -0500
I use raid-5 for all diskpools.

Although I don't agree with no raid, in some instances it is less of an issue 
than others.

A few of my pools use caching for some of our more popular servers that get 
restores.
As well as our daily exchange and db backups.

Can't think of a single instance where calling a group back and saying we need 
you to resend a couple servers because a disk died on the backup server. I'm 
not saying that it is a huge issue, but from the mindset of the end users and 
upper management that we, the retention team, has not protected itself from a 
disk failure to save a tb or so of space would be very difficult to swallow.



-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of 
Kelly Lipp
Sent: Monday, August 09, 2010 11:24 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: Raid 1 vs Raid 5

I'll amplify what Skylar said: if your goal for this disk pool is short term
storage then I probably wouldn't use any RAID protection as the data will be
backed up to tape and then migrated to tape again.  And as Skylar said,
worst case, the client will send it again if it somehow escapes.

Conserve space: don't RAID...

Kelly J. Lipp
O: 719-531-5574 C: 719-238-5239
kellyjlipp AT yahoo DOT com

-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Skylar Thompson
Sent: Monday, August 09, 2010 9:33 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: [ADSM-L] Raid 1 vs Raid 5

Do you have tape in your primary storage hierarchy? If so, remember that
even if part of your disk pool fails, you only lose access to the data
that are on the failed volumes. You can then regenerate that data by
either running another backup from the nodes that had backed up to that
volume (if the backup to the copy pool hasn't happened yet) or from the
copy pool. New backups can continue against the disk pool volumes that
are still available, or can be cut through directly to tape if the
entire pool is unavailable.

On 08/09/10 08:23, Dana Holland wrote:
> Does anyone have opinions about setting up storage pools as Raid 1 as
> opposed to Raid 5? We have a very limited amount of disk space at the
> moment and don't know when we'll get approval to buy more. At the time
> we first started planning to implement TSM, we purchased what we thought
> would be plenty of storage. But, that was 4 years ago - and our usage
> has grown. Now, if I choose Raid 1, I barely have enough to create a
> primary and copy storage pool for one of our servers. And that isn't
> allowing for any growth at all. And I'm not sure how much additional
> space incremental backups would take. I know Raid 5 would give me more
> storage space, but I've also read that it's harder to recover from if
> there's a disk failure (read this on a TSM site somewhere). So, I'm
> wondering what some of you are using?
>
>
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--
-- Skylar Thompson (skylar2 AT u.washington DOT edu)
-- Genome Sciences Department, System Administrator
-- Foege Building S048, (206)-685-7354
-- University of Washington School of Medicine

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