Eric,
Lets say I'm with a LARGE storage company, involved solely in storage &
that's what I've been doing for the past 8 years.... Storage. So as not
to cloud the waters with company propaganda, there are many excellent
subsystems out there.... Some are truly better than others.
Bottom line is it comes down to what your requirements are before a
recommendation can be made. Several factors should be considered before
"jumping in" and putting an array on your server. A couple of things
that I always spend time with engineers reviewing is RAID itself.
Everyone "thinks" they know it, but when the rubber meets the road many
subtle differences will rear their ugly head.
Couple of things to consider:
What actually IS the requirement? Size / speed / growth / fault recovery
/ redundancy
What type of data? Small block / large block / print & file / database
(tables-logs-swap)
What's the IO requirement? Gather a week or so SAR data at 15 second
increments on your present subsystem. This will reveal many important
things that can potentially save you a TON of Cash (and cache too), or
quite possibly show the glaring inefficiencies of what your dealing
with. The IMPORTANT thing in SAR is the "-d" flag
What about consolidation? Replication?
Many of these answers will begin to paint a picture of the IO
requirements, something that you simply cannot just throw a bunch of
disks at. The way these are defined, presented and optimized will play a
major role in the success of your project. An excellent primer on RAID
was published by the RAB (Raid Advisory Board) several years back called
"The RAIDbook". I have about 20 copies & if you want to send me your
address off-line Ill be happy to forward you a copy.
Start there before you jump in and put all your eggs into one RAID
basket.... RAID-5 Gives you protection, but at a heavy price (that is
not always obvious). I would get into several vendors white papers, try
to fully understand the semantics, ask MANY questions, and run tests. Of
course if this is simply a low budget single server and its more of an
educational experience, by all means try out anything you can.
Regards
Matt
-----Original Message-----
From: owner-linux-xfs@xxxxxxxxxxx [mailto:owner-linux-xfs@xxxxxxxxxxx]
On Behalf Of Eric Peters
Sent: Tuesday, December 18, 2001 3:52 PM
To: linux-xfs@xxxxxxxxxxx
Subject: Re: Pulling disk out of the RAID 5 Array?
I'm following this thread with great interest, what hardware
configuration would any of you recommend for this type of hot swap and
go system - I want to be able and have some data redundancy for a couple
of web servers I have at the harddrive level - where I could swap out a
bad disk and still have the server reving - gradually rebuilding the
replaced mirror/or parity drive/etc
Thanks!
Eric
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