Raid 1 or Raid 5 - which one? 1

[FAC17]

I am configuring a new server. I don't know if I should choose the less expensive Raid 1 or go with the Raid 5.

This server is a Dell PwerEdge 1600 SC. It is used mostly as an application server but also functions as a document server. Nothing high powered or huge. Just normal stuff for a 16 person law office. We are mainly interested in good performance and fault tolerance.

I have been reading about the two types of Raid and can't decide which would be better.

Your input would be appreciated.

Thanks!

FAC

 

[FredUG]

I would use RAID-5, if a drive fails you'll slow down a little but once you replace the drive it will rebuild itself. RAID-5 provides fault tolerance and some performance benefits.

Good luck,

FredUG

 

[comtec17]

This would depend on the use of the applications and files. If you will have more reads than writes I would suggest using RAID 1. If you will have a mix of reads and writes (Random I/O) then RAID 5 will do the trick.

 

[FredUG]

As an APP/file server, I suspect there will be plenty of writing going on, especially since it's a law firm. You could always setup a perfmon to check reads vs writes to be sure.

FredUG

 

[RB5]

RAID5 is the less expensive type of RAID when compared to RAID1. RAID5 has the parity striped across all of the disk drives. RAID1, on the other hand, is mirroring. So, you must double up your disks and is, therefore, more expensive. For example, if you have a 140 GB usable storage requirement, to run RAID1 would require 4-73 GB disks, 2-73 GB disks to meet the 140 GB usable storage requirement and 2-73 GB drives to make the mirror for the RAID protection. However, you would only need 3-73GB disks for a RAID5 configuration since 2/3 of all three disks together are being used for data and the other 1/3 of the disks is used for parity. So, you save money by not having to buy that 4th disk drive as required for the RAID1 configuration. Now, multiply that into multiple TBs and you can see that you must plan your RAID types based on your applications and storage requirements. I usually deal in multiple TBs of data requirements (currently, I'm working at a Data Center that has approx. 43 TBs of data using 3 EMC Symmetrix Arrays - so RAID1 vs. RAID5 can get real expensive!).

Continuing, RAID1 gives you the best performance for both reads and writes of any kind of RAID type that is available. An example of must use RAID1 are for database applications, like Oracle and SQL Server, if they are write intensive. However, RAID5, being cheaper, provides medium write performance and good read performance. Using RAID5 for databases is asking for trouble! The performance is not going to be there. You might get away with a RAID5 configuration if you are only doing database read operations.

Since you mentioned that you don't have any high powered applications and are also saving documentation (BTW, my wife is a paralegal), RAID5 should do just fine for you.

Good luck and let me know how you fair out.

 

[FAC17]

Thanks one and all for the input!

RB5 - after reading your post I am a bit confused. Perhaps the RAID1 is more expensive when you get to LARGE machines. On the quotes I have from Dell - the RAID5 is 10% higher than the quote for RAID1. The current server has 2 20 GIG drives (RAID 1). Theses drives are only 1/2 full. So Dell quoted 2 36Gig drives for the RAID 1 machine and 3 36Gig drives for the RAID 5. They are also apparently getting more $ for the RAID 5 controller.

Also for your consideration - they use Abacus and PhoneSlips the rest of the stored data is MSWord Documents.

One thing we are considering is scanning and storing more of their large paper files on CD. Here I believe the Raid 5 might be less costly. I assume to expand disk storage on RAID 1, we would have to always buy a pair of disks. For the RAID 5, can I just expand the array with another disk? Does the size have to match the size of the other disks?

Any thoughts on this? Thanks for your time and brain use!

 

[FredUG]

> I assume to expand disk storage on RAID 1, we would have to always buy a pair of disks.

Correct.


> For the RAID 5, can I just expand the array with another disk?

Yes. Always make backups just in case.

> Does the size have to match the size of the other disks?

RAID drives should be identical. If you want to use bigger drives you'd need to create a new array with matching drives.

Hope that helps,

FredUG

 

[nsnook]

You may also want to look into Non-windows based raid servers, such as SNAP servers, custom Redhat servers, or ReByte servers. They tend to be cheaper in terms of maintenance and are generally a little cheaper to buy.

I RARELY sell Windows based raid servers. Only when a customer insists, or really wants to run Exchange / Terminal services.

SNAP servers, like the 2200, can cost $1600 for RAID 1 (mirrored) 240gig (120 usable).

Redhat servers are usually something I do as a custom build.

ReByte is a cool RAID card around $200 that gets installed into pretty much any old computer (Pentium I, 166 minimum) and you pick whichever HDDs you want. It does both RAID 1 & RAID 5.

This is just meant to give you more information & add some options.

To tell you the truth though, 80 % of my small business clients (mostly small Law firms, Accountants, Engineers) use Linux based server solutions.

 

[FredUG]

Actually, most RAID is DAS or SAN not NAS. NAS is getting more popular and it's evolving to include better features. I would NEVER suggest my clients use linsux for anything. There are always better solutions. If you want a better NAS box look at Fastora, it's FreeBSD based not linsux based.

Hope that helped,

FredUG