[OPLINTECH] RAID 5 vs. RAID 10 on a file server

[Shane I. Hoffman]

I use Raid 6 and have had good luck with that.  I’d be wary of Raid 5.  Due to the size of newer drives, the possibility of losing another during rebuild is pretty real.  RAID 6 gives you the ability to lose 2 drives.

Has anyone looked into the JBoD capabilities in the newer MS Server OSs?  I’m starting to look at that as I’m replacing my servers in the spring.

From: oplintech-bounces at lists.oplin.org [mailto:oplintech-bounces at lists.oplin.org] On Behalf Of Chad Neeper
Sent: Wednesday, December 2, 2015 12:24 PM
To: oplintech at lists.oplin.org
Subject: Re: [OPLINTECH] RAID 5 vs. RAID 10 on a file server

http://www.adaptec.com/en-us/solutions/raid_levels.html

That's a good write-up and comparison of the various types of RAID. Each type has it's own characteristics, strengths, and weaknesses and you really need to assess your own scenario and requirements to determine what type of array will work best for your particular needs.

In my own experience, I do use RAID 5 and I use RAID 1. On a purely comfort level, I've always felt the most comfortable using RAID1...simply because ALL of the data resides in a complete and usable form on a single drive. In an absolute catastrophe with absolutely critical data, I could even take one failed/failing drive out and stick in into a plain old workstation for recovery/repair efforts or even send it off to be repaired, if I needed to go to that level (I never have). I've never lost data on a RAID1.

On the other hand, I have been bitten by a RAID controller with firmware that didn't safely handle a RAID5 array with a marginal drive. It pretty much ruined the whole array. Twice. Each time, I had to rebuild the array and recover the data from backup. Fortunately, it was just my own in-house company server and didn't store irreplaceable data. But still a PIA and I've since then been a little gun-shy of arrays that require multiple drives to store a single set of data (basically, anything that isn't a RAID1).

But I still do usually use RAID 5 because it has a good balance between reliability, performance, cost, and allows the creation of a large single array. You've given me some food for thought, though. With hard drives having commodity-level prices these days, maybe it's time to take a closer look at 10.

WRT RAID10, it does seem that 10 performs better for both reads and writes, although RAID5 can perform equally well in an environment with more reads than writes. RAID 10 can also potentially sustain more drive failures before data loss vs RAID 5. But you pay more for 10. There's lots of technical analysis and info about 10 vs 5 (and RAID in general), if you Google for it.


Bottom line, you'll have to figure your own needs and find the array that best suits your specific balance between reliability, performance characteristics, and cost. Also, always use a hardware array. Always have a hot spare available And always use ECC RAM!

$.02,
Chad

______________________________
Chad Neeper
Senior Systems Engineer

Level 9 Networks
740-548-8070 (voice)
866-214-6607 (fax)

Full IT/Computer consulting services -- Specialized in libraries and schools

On Wed, Dec 2, 2015 at 11:10 AM, Jim Lack <J.Lack at rrpl.org<mailto:J.Lack at rrpl.org>> wrote:
Thanks Jessica.  I guess I’m at the other end of the spectrum.  All our servers have RAID 5 setups and I’ve never come across an issue of having downtime.  Sure, I’ve had drives go bad but the systems keep plugging away until I get a replacement drive in.  I just don’t know if there is a huge benefit if I move to RAID 10.  Thanks for your input!!

From: Jessica D. Dooley [mailto:dooleyje at adamscolibrary.org<mailto:dooleyje at adamscolibrary.org>]
Sent: Wednesday, December 02, 2015 11:01 AM
To: Jim Lack
Subject: RE: [OPLINTECH] RAID 5 vs. RAID 10 on a file server

Hi Jim,

I can’t speak to the reputed performance benefits of RAID 10, since I’ve never used it, but I have four servers, including two domain controllers, running RAID 5, and I would never choose that configuration again. I have a virtual host and NAS box running multiple instances of RAID 1, but not configured for striping. RAID 1 with a hot spare would be my configuration of choice in the future. The servers configured with RAID 5 have failed on more than one occasion; even with backups, it’s a significant interruption. I’d be interested to hear if anyone has committed a large environment to RAID 10, and has seen noticeable performance benefits. Our domain controllers and member servers also double as file storage, with DFS replication configured. I’d downvote RAID 5 on reliability alone – fwiw.

Thanks,

Jessica D. Dooley
IT Specialist
Adams County Public Library
937-587-2085<tel:937-587-2085>
dooleyje at adamscolibrary.org<mailto:dooleyje at adamscolibrary.org>

From: Jim Lack [mailto:J.Lack at rrpl.org]
Sent: Wednesday, December 02, 2015 10:43 AM
To: oplintech at lists.oplin.org<mailto:oplintech at lists.oplin.org>
Subject: [OPLINTECH] RAID 5 vs. RAID 10 on a file server

I need to replace my current domain controller with a new server.  The server also acts as our main file server.  Our current server is set up with two drives, configured in a RAID one setup which houses just the OS (Windows Server 2008).  We have three additional drives set up with RAID 5 which houses all of our user files.  We also have an additional drive as a global hot spare.

I’m wrestling with the option of using RAID 10 on our new server (someone suggested it).  Do I sacrifice a couple of drives in RAID 10 for performance or should I just stick with the RAID 1 (OS) and RAID 5 configuration?  I’m just wondering if there will be a big benefit going with RAID 10.  There’s a lot of smart people on this list and I value your opinions.  Let me know your thoughts

Thank You,

Jim Lack
Technology Support Manager
Rocky River Public Library
1600 Hampton Rd.
Rocky River, OH  44116
440-895-3765<tel:440-895-3765>


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