[rescue] somewhat OT: secondary market storage?

[Chris Byrne]

I'd say this qualifies for rescue materiel.

Anyway it's a very complicated topic. In a general sort of way heres the
breakdown.

The performance of any software RAID isnt even in the same league with what
a good hardware RAID setupcan do. Dont even try and compare either
performance or reliability.

For relativley small amounts of storage,or  relativley small numbers of
transactions, on a single or very few machines, then properly architected
and configured directly attached high performance local disks with good
quality high perf controllers and lots of cache almost always beat the hell
out of a storage array.

Whether the storage (local or array) is straight SCSI of FC doesnt really
make that much difference, since the effective throughput from the drives is
going to be the same. It takes a hell of a lot of drives doing a hell of a
lot of work to fill up either FC or U160

You start seeing the benefits of a large scale array (most are now FC) when
you have to deal with large amounts of highly available storage (over say
500gb, large numbers of transactions, or large numbers of clients. With
local disk theres only so much you can handle. A good array should be able
to handle many times the I/O load that a single machine can generate. It
should also scale to far more usable storage than any machine could handle
locally.

Think of say an E450. Good midsize server with 4 procs, max ram, and max
disks. You are still talking about a maximum usable raid 1 storage capacity
of well under a terrabyte, and if you are very lucky 256 meg of dedicated
cache (most raid cards have a lot less, though there are a few that have
more). A large scale storage array cmay be able to scale to 500 terrabytes
and have up to 32gb of cache.

Chris Byrne



-----Original Message-----
From: rescue-admin at sunhelp.org [mailto:rescue-admin at sunhelp.org]On
Behalf Of David Rouse
Sent: 01 April 2002 23:30
To: rescue at sunhelp.org
Subject: Re: [rescue] somewhat OT: secondary market storage?


On Monday, April 1, 2002, at 12:45 PM, Derrick D. Daugherty wrote:

>
> oracle will live here.  anyone have much luck with the t3 arrays?  I'm
> adverse to them for db's since they're raid5, but if the performance is
> good...  in the past i remember reading things about the clariion kit
> that made me dislike them, anyone have an argument for them?

In a related issue, how does FC-AL type boxes compare (speed and
reliability) with, directly attached SCSI disks with multiple
controllers and DiskSuite running 0+1?

All I have ever seen has been directly attached SCSI, so I don't have
anything to compare with.

I understand if this needs to be Geeks, and hopefully this isn't war
bait...

--
David Rouse