Re: 280R and A5200 question

From: Juhan Leemet (juhan_at_logicognosis.com)
Date: 06/30/04 

Date: Wed, 30 Jun 2004 03:29:09 -0200

On Tue, 29 Jun 2004 21:20:53 -0400, Dennis Clarke wrote:
> On Tue, 29 Jun 2004, Rich Pierson wrote:
>> I just finished racking and installing a new to me 280R Sunfire and an a
>> 5200 with 12 discs, Solaris9 from the dvd. Six in front and 6 in back.

You don't say what the purpose of this storage is, i.e. access stats.
 
> Good config. That should work well. I guess that you are not using an
> additional controller or fibre HBA ?
>
>> Format sees them fine plus the two internal hard drives on the sunfire.
>> Everything is up and running.
>> I want to make 2 raid arrays
>
> You seem to want RAID for some reason. My only advice is "don't do that."
> The A5200 does not provide a hardware RAID controller...
> For now I simply suggest that you do not perform a RAID setup. The
> performance is terrible. Go with a stripe with reasonable stripe depth.

While I would generally agree with this advice, I think the design
tradeoff(s) should take into account the usage.

While it is true that in my case I measured a 5x disk I/O overhead with
Solaris9 SVM S/W RAID on a 711 array I setup for my own use, I'm still
happy to use it that way. My usage is: seldom write, occasionally read, in
a code repository for reference purposes. S/W RAID5 works fine for me: max
storage efficiency and reasonable (for me) performance, with drive failure
protection (5 drives on-line and 1 hotspare). Depends on the situation.

The fibre array should perform better than my old SCSI-W 711 on Ultra2.

I would say: if you can stand writing to your disk array at 1/5th the
normal write throughput, S/W RAID5 might still be a viable alternative,
otherwise don't consider it, and go with mirroring instead. Note that
reading from S/W RAID5 is pretty good, since it is (sort of) striped.

Although... as you imply... H/W RAID controller with lots of battery
backed cache and many internal SCSI channels would be ideally flexible.
However, that is quite a different animal, with an expensive pedigree. 

-- 
Juhan Leemet
Logicognosis, Inc.

Relevant Pages

  • Re: asm on san
    ... everyone inside oracle corp was migrating to that kind of hardware ... religion against raid 5 from this poster. ... The "baarf" crowd has been around a long time, back when companies allowed you to have a single server w/locally attached storage for your app. ... And not to mention the fact that you could be on an array with 10 other systems connected - competing for both bus bandwidth and spindle access due to the virtualization of the LUNs within that array. ...
    (comp.databases.oracle.server)
  • Software RAID-1 with Mandrake9.0 problems - LONG
    ... I have configured RAID -1 ... md: md0: raid array is not clean -- starting background reconstruction ... ...trying to set up timer as Virtual Wire IRQ... ... host bus clock speed is 132.8612 MHz. ...
    (comp.os.linux.setup)
  • Re: Problems with software RAID on SATA
    ... Connected to this are two 320GB drives ... >>which I want to turn into a RAID1 array. ... >>I'm almost certain it's a problem with initting the RAID arrays at boot. ...
    (Debian-User)
  • Re: RAID newbie...can I have several partitions on a RAID 1 array?
    ... You haven't expounded upon why you think you need raid. ... better backup device rather than buy 2 cheap RAID HBAs. ... RAID array then I would have to replace the mobo with the same one or at ... Lets say, for example, you buy 2 identical model drives, from ...
    (comp.sys.ibm.pc.hardware.storage)
  • Re: [PATCH 000 of 5] md: Introduction
    ... "why linux raid isn't Raid really, why it can be worse than plain disk") ... After this, the array ... error is in the filesystem, due to the complex layout of raid5. ... hundreds or 1000s of drives, you've quite high probability that some of them will fail sometimes, or will develop a bad sector etc). ...
    (Linux-Kernel)