HP IR Volume?

[Doug Short]

I am new to the Itanium class world so please be gentle...

I am configuring an ia64 rx6600 server. It has (2) physical internal 146gb disks on the SAS controller. These are apparently in some sort of internal raid configuration as when I do an ioscan I only have one path to the disks. I was unaware at time of purchase that these disks were in an internal raid (if I'm even right in my presumption about that). I had also purchased MirrorUX as well as that is our standard package so to speak. However with only 1 logical disk presenting itself due to this IR volume, I'm not able to utilize mirroring. So I see my options as this:
1. Don't use MirrorUX
2. Order 2 more internal drives and use MirrorUX, or
3. Somehow break the internal raid and use the 2 physical disks as just physical disks.

Am I missing something else that is a possibility here? Any and all help is greatly appreciated, thanks.

Doug

root@chcccmx1:/# ioscan -fnC disk
Class I H/W Path Driver S/W State H/W Type Description
====================================================================================
disk 2 0/0/2/1.0.16.0.0 sdisk CLAIMED DEVICE TEAC DV-28E-V
/dev/cdrom /dev/rdsk/c0t0d0
/dev/dsk/c0t0d0
disk 1 0/4/1/0.0.0.0.0 sdisk CLAIMED DEVICE HP IR Volume
/dev/dsk/c3t0d0 /dev/rdsk/c3t0d0
/dev/dsk/c3t0d0s1 /dev/rdsk/c3t0d0s1
/dev/dsk/c3t0d0s2 /dev/rdsk/c3t0d0s2
/dev/dsk/c3t0d0s3 /dev/rdsk/c3t0d0s3

[Tim Nelson · Accepted solution]

The rx6600s come with an SAS raid controller. It can be configured to Raid 1 the internal disk(s) ( i.e. HW raid ) the OS will then only see 1 disk.

It is up to you what you want to do as any option you listed above is a valid option.

Opinion,
why pay for Mirror/UX if you do not have to. If you need it for other things then use it for everything to be consistent.

I am using the HW raid option from the controller. The rest of my storage is san based.

[Doug Short]

Mr. Nelson, thanks for your quick response, and for the record I share your opinion. However, at this point the decision on what to do is above my pay grade so I'm just trying to gather options to present to the powers that be. If I were to want to pursue option 3, and break the raid, can you point me in the direction of some documentation to possibly exercise this option? Again, any help is greatly appreciated.

Doug

[Torsten.]

Look at your config (if sasd0 is your device file):

# sasmgr get_info -D /dev/sasd0 -q raid

This is a hardware RAID1 (mirror).

In this combination it is much better to manage than with LVM (at least in this system, because it is SAS).

Don't change anything!

Post the result if you want more info.

[Doug Short]

Ok, here are the results of the sasmgr command:

# ./sasmgr get_info -D /dev/sasd0 -q raid

Fri Feb 1 10:56:06 2008

---------- LOGICAL DRIVE 7 ----------

Raid Level : RAID 1
Volume sas address : 0x3e7f53903774801
Device Special File : /dev/rdsk/c3t0d0
Raid State : OPTIMAL
Raid Status Flag : ENABLED
Raid Size : 139898
Rebuild Rate : 0.00 %
Rebuild Progress : 100.00 %

Participating Physical Drive(s) :

SAS Address Enc Bay Size(MB) Type State

0x5000cca00019da59 1 7 140014 PRIMARY ONLINE
0x5000cca00019dc49 1 8 140014 SECONDARY ONLINE

Based on this, I see that it is a raid1. Given that, it is likely the most economical solution to not use MirrorUX, or at least in my opinion that's the case. This should provide adequate redundancy. Thanks!

[Torsten.]

A hardware RAID is always a good solution.
If one drive fails, replace it and your are done. If you use mirror/ux and you have to replace a SAS disk on this internal controller - it's a tough job, because you have to deal with self-changing device files ...

But this controller can only mirror 1 disk to another + a spare = that's it. For all other disks you need to use LVM together with the "plain" disks.

Another "workaround" option is the upgrade to the smartarray P400.

But as long as you have only 2 internal disks, use the integrated raid.

[TTr]

The default internal controller is a RAID controller BUT it has its limitations. You can only RAID upto 5 disks with it, (two mirrored pairs -two separate volumes- and one hot spare). The remaining ones if they need to be mirrored, you must use MirrorUX. If you are not going to use more than 2 or 4 internal disks and not have any external JBOD then you do NOT need MirrorUX. To RAID more than that you need to upgrade the internal controller but then you are crossing into performance/bandwidth territories.

I use the internal RAID controlers in many servers and have no problem with the setup and the perfromance.

[Doug Short]

Thanks for all of the helpful instructions here. This gives me the information that I needed to make an informed suggestion to my customer. Thanks again.

Doug