[lists] Re: [NMLUG] More RAID Questions

[kwilson at swcp.com (Kelly Wilson)]

Something I meant to add to my last post.  Get a couple of removeable 
drive cages for your RAID drives.   Label everything clearly.  If you 
prep someone at the remote site, they can do drive swaps for you with 
phone support.  Saves tons of hassle.  Regardless of needing special 
hardware, doing RAID is worth spending a bit on a good hardware 
controller.  If you get one with an onboard cache, you'll definitely 
notice an improvement on a file/print server over doing it in software.  
Besides, if you're using just the onboard IDE and it dies, you're down 
to replacing the motherboard or adding a controller anyhow.
Yes, RAID 5 is the least overhead for parity but RAID 1 is a better 
tradeoff if performance is an issue.
Remember this too...with software RAID, failover is a manual process, 
with hardware it's generally just swap a hotpluggable drive cage and 
you're done.  I guess it all depends on how hands-on you can be and how 
much downtime you can tolerate when a problem occurs.
-- 
Kelly Wilson

Ed Heron wrote:

 My 2 cents...

 Software RAID eliminates the need for special hardware.  I also 
perceive that as a good thing.

 In either case, hardware or software, RAID re-syncing should be low 
priority and not reduce system performance.  However, I'd want to test 
it if it were important.

 RAID 5 (3 drives or more) should be the preferred goal.  You would get 
both mirroring, to avoid drive failures, and stripping, to increase 
device capacity cheaply.  However, unless you need a hugmongeous single 
partition, RAID 1 really should do you.

 I evaluated the RAID 1 idea briefly.  I concluded that mirrored servers 
would be the true ideal, from a fault-tolerant point of view.  As soon 
as I resolve configuration issues for all of the software I'll be 
running on my new servers, I'll be looking into methods for 
accomplishing it.  Many of my servers are more than 2 hours away and a 
failure would significantly degrade services.  RAID 1 only helps the 
system survive if the failure is a hard drive.

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