Setting up RAID5 with three SAS Disks.. Need two partitions.

[JonathanAnon]

Hi, 

I have three SAS disks and I wish to set RAID 5 and have two partitions, one for the System and one for Data. Currently I am doing the following:

In Array Configuration Utility:

1. I create one array with the three disks

2. The SAS array is created. 

3.  When the array is created, I then create the first logical drive. This is my C: System drive in Windows. 

4. Then within the same array I create a second logical drive. This will then be my D: drive in Windows. 

I then run HP Intelligent Provisioning and let it install Windows for me... This works but I'm not sure it's the best way. Am I doing something wrong?

[Sbrown]

that is fine but you can also just make one big partition LD and then during setup carve up the space. One is much easier to adjust

[TVVJ]

The entire process of creating a RAID array, creating logical drive(s) and installing operating system, which is the way a fresh installation is done, can also be completely done from within Intelligent Provisioning environment. Ensure that Intelligent Provisioning in the server is the latest to ensure that the server has the latest firmware and support pack.

As such there are no issues stated in the methodology stated in the post.

For more information on utilizing Intelligent Provisioning for installing the operating system, refer to section "Configuring the server and installing an OS" in it’s user guide. Click here to access Intelligent  Provisioning user guide.

Regards,

Vijayasarathy

[JonathanAnon]

Hi Vijayasarathy, 

I boot to Intelligent Provisioning the I choose Perform Maintenance and do the ACU work in there... When I'm finished I come back out to the main menu again and choose Configure And Install and proceed with the Windows installation (once the RAID has been set up)... 

But when I create one large logical disk.... instead of two logical disks as in my original post..  there is nowhere in the Intelligent Provisioning install that it allows me to partition the single logical disk in to two parts... When the installation is finished I have one logical drive and one large C: partition. What way would you recommend to set it up with the two partitions. ?

[Sbrown]

windows 2008 allows you to shrink your partition of C:. I just did 300gb to 100gb, then created a D: E: F: for (database,tempdb,log).

The key is to never use [f8] to setup raid, if you do that, you may never get the chance to slice and dice!

I'd strongly recommend a 4th drive and raid-10. I've had two failures that would have killed raid-5 twice in my life.

Plus a cold shutdown (crash/power loss) requires smart array to rescan the entire raid-5 - which degrades performance greatly for a period of time to rescan.

Just a protip: RAID-10 ftw!

Also if you have 4 drives, you could do RAID-10 boot 100gb for speed, then raid-5 for the rest of the volume for extra storage!

great idea huh?

[JonathanAnon]

Sbrown, 

I normally deal with the small business sector, so we would have usually only implemented either RAID 1 or RAID 5, purely based on fewer disks and lower cost.

We are now looking at implementing Hyper-V (with two virtual servers) on the one physical machine.. on our typical small business site we would usually have installed two physical servers ... so maybe the fact that we are now using one physical machine, it might be a good idea to look at RAID10 for the Hypervisor.. 

It's certainly a good suggestion, which I will look in to. 

regards, 

J

[Sbrown]

I think most people will agree raid-5 only for most virtualization projects is pretty bad idea.

You can overcome some issues with HP SmartCache but that only helps read latency at this time. It also helps rebuild time.

But the cost of doing that would be far more expensive than choosing more spindles of enterprise drives (no sata or nearline SAS hard drives!).

End up with cpu's running at 10-20% all the time in maximum power saving mode waiting for disk i/o to complete.