Help: IBM x3650 M2 Raid 10 Configuration

[amznilla]

Guys,

We have a IBM x3650 M2 server (IBM ServeRAID MR10i SAS/SATA Controller) w/ 8 disk (135.972GB per disk). Now, I've already configured the RAID 10 and most of the settings are by default (see image below). Did i configured it properly or is there any other way since we will be installing Windows 2003 SP2 R2 Enterprise (32-Bit) and MSSQL 2005 SP2 Enterprise (32-bit) What is the best configuration that we can do? And also if i create a partition do i need to use the mirror option? Hoping for your advise. Thanks.

 

[technome]

You are setup correctly.
Once you start the Windows install, apply the necessay raid driver, do not accept the Windows default to use the entire unallocated space to install Windows. Create a partition of spproc 50-60 Gb for the Os/programs. Once in Windows go to DiskManager and you will see the c: drive and unallocate space. From the unallocated space, create a partition for your data. Having aseparate partition for the OS and the data makes management of files easier and safer, easier if corruption or virus attack affect the system.
The default settings for the raid parameter are fine unless you have a server strictly dedicated to say a database or other program such as Exchange.
You already have a mirror from the raid setup, Windows knows nothing about it, you will only see the c: drive and the unallocated space.
Personally with the number of drives, I would order a spare disk to have on hand even if the drives are warranteed. I assume you have 8 drive bays, if you have more you should setup the spare drive as a hotspare.
Raid 10 is a good choice for speed and safety, safer and faster then raid 5.


........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

 

[goombawaho]

I would order a spare disk to have on hand even if the drives are warranteed.

Excellent advice. If you don't have a (global) hot spare in the server, at least have a drive sitting on the shelf. With that many drives in service, I would have both. Things go from bad to worse very quickly and often drives can fail pretty close to each other given MTBF and bad luck. It's happened to me.

 

[technome]

One of my clients, beyond cheap, and the office manager being self destructive( really) would not go for a hotspare or cold spare, or backup as it was to much trouble. The manager did not get a replacement drive for a degraded raid 5 array for 3 1/2 weeks after I gave the person a link to a suppler with warnings to get the drive immediately...the array failed, with 958K Word/Excel files, one day before the replacement drive arrived. This same manager previously allowed other system drives to fail, and I resuurected the data; the last time the only way to get the drive going was to freeze the drive in my freezer. This time they pay the price.



........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

 

[goombawaho]

Similar experience with an email server (circa 2001). 9GB SCSI drives in a RAID 5 with a hot spare. Needed more disk space. No more room for hard drives. Folded RAID 5 hot spare into array (space problem solved). Fast forward 6-8 months. One drive dies - okay, no problem. Hard drive on order, 2nd drive dies. Dead in water. Should have had drive on SHELF.

My advice to have ON HAND was not heeded.

 

[amznilla]

Ok.. i will need to reconfigure the raid setup, please see below:

Step1: Create Raid 1 (Mirroring)
RAID 1: Physical Disks: (Span: 0)
Slot: 0 - 135.972GB
Slot: 1 - 135.972GB
Stripe Size - ? (Now, what would be the most appropriate stripe for maximum performance?)
Select Size - ? (Should use all of them? This will the OS reside right?)
Now i will run the ServerGuide CD, what will be the process for this?

Step 2: Create Raid 10 (stripe mirroring)
RAID 10: Physical Disks: (Span: 1)
Slot: 2 - 135.972GB
Slot: 3 - 135.972GB
Slot: 4 - 135.972GB
Slot: 5 - 135.972GB
Slot: 6 - 135.972GB
Slot: 7 - 135.972GB
Stripe Size - default (64k) or maximum (1024k)? (The maximum stripe size is 1024k)
Select Size - ? (Should use all of them? This will the MSSQL, database files (bak/trn and .mdf/.ldf) reside)
Now i will run the ServerGuide CD, what will be the process for this?

 

[technome]

Amznilla...
Your original setup was the best for speed, If you lower the number of drive pairs in the raid 10, you sacrifice speed and you lower the size of the raid 10 capacity, so I would go keep your original setup. If you had ten or more drive slots, then I might go with the raid 1 and the raid 10.

Your second setup does provide a bit more safety, as the OS would be isolated from the data array, and having two completely separate arrays provides multiple spindle sets, a plus in having SQL tmp/log files running on different spindles from the SQL database but In my opinion if you run the SQL tmp/logs files on the raid 1, the performance of the raid 1 ( being so much slower the the raid 10, especially a raid 10 with more then the minimum 4 drives) does not make it worthwhile, basically you not gaining any performance due to the extra spindle set, you are lowering it. Raid 1 only READS from the fastest drive in a raid 1 (controller chooses it) and only WRITES to that drive first, once the data is committed, it then WRITES to the second drive...so raid 1 has inheritant delays. The raid adapters cache makes up for much of the delays, but not if the server is slightly stressed , at that point the cache is flooded and does not make up for the delays; if a server's disk lights go solid, the cache is likely flooded. If only a few entry are inputted in a short time or a small report is done, then the raid adapters cache makes up for the raid 1 delays; if the server disk lights are flickering, on/off, then the cache is not likely flooded.

Now, if you had more drive bays, and unlimited resources, then you could have a 4 drive raid 10 for the OS/programs/tmp/log files and a 6 or 8 drive raid 10 for the SQL, then the multiple spindle set would make sense. Or if you had an SSD raid 1 and a 6-8 drive raid 10, or Cachecade v2 setup....I'm getting carried away.

Most of my clients can't afford raid 10, so they go for slower raid 5, and most have SQL, speed is fast, so your original setup will be very fast.

Choosing the best stripe size is difficult. To find the fastest stipe size would require benchmarking with your data, as it is dependant upon the data chunk size. Choosing different stripe sizes is a trade off, if you choose a size which increases your database speed, it will lower your OS and other program's/data speed. If your server will only be used for SQL then it would be worth benchmarking to find the optimal stripe size. If the server is going to be used for SQL and other data, such as Word/Excel/other program data then the best choice is to go with the DEFAULT size. Even if it is strictly for SQL, and you stick with the default size, you will still have a fast server.
If you do want to play with the stripe size, unless things have change since the last time I tweaked the stripe size and benchmarked the results ( been a few years), the stripe size can be changed without destroying the array in raid 10 (not possible with raid 5), as long as you do not allow the array to initialize. Obviously do not work with live data, work with a copy of your data. If you do want to play with the stripe size, by all means use bench mark programs, but also check you speed by going into your SQL program, and run what ever you do on a normal basis to see the reponsiveness. Benchmark results mean little if the areas in SQL you use slow down.

Now to really add complexity to the performance issue, google IBM Cachecade v2 performance

........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

 

[goombawaho]

i will need to reconfigure the raid setup

You mean WANT to reconfigure it. Why bother, the other setup will work. Extra hard drives is a better insurance plan than any RAID setup. It all gets to be very subjective as to the best setup.