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Subject: Assigning disk inner and outer halves to LUN

Simon Haslam
Advisor

Subject: Assigning disk inner and outer halves to LUN

I'm specifying a DL360 G5 (dual quad)/P400i which will be running a number of VMs. I need RAID protection on at least one LUN.

Is it possible to split a physical disk into inner and outer halves and assign each half to a different logical drive?

For example, if I had 4 x 146GB disks I would put RAID1+0 on the outer 4 halves (i.e. giving me around 140GB protected) and then could use the remaining 4 inner halves 1-4 RAID0 drives.

This should give the best performance for the high traffic RAID1+0 but still leave useful space for, say, backing up VMs which would only happen at quiet times.

Presumably if such a configuration is possible it would only be possible with ACU? If so, how would I get ACU to run - would I have to install a temporary OS on a single disk, install ACU, configure the 2 (inner and outer RAID 1+0) LUNs on 4 disks, then install the proper OS on one of the new LUNs?

I have tried to fathom this out from the manuals but they only seem to talk about allocating a whole physical disk to an logical drive...

-Simon
3 REPLIES
Uwe Zessin
Honored Contributor

Re: Subject: Assigning disk inner and outer halves to LUN

You can create multiple logical drives within a disk drive array and they can be created with different RAID levels, so it looks like it is possible what you want.

There is no placement control available, but I'd guess if you create the RAID1+0 first, the logical disk will be on the outer area of the disk.
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Simon Haslam
Advisor

Re: Subject: Assigning disk inner and outer halves to LUN

Thanks Uwe - that sounds reasonable. I wonder if it's possible to confirm that it will start placement at the outside first? Ideally I'd be interested if anyone has tried it and perhaps done some tests with IOzone etc.

Regarding the second part of the question - do I have to install ACU on the host itself or is there a clever way to either run ACU from a bootable CDROM or a management PC? Or can I do this from ORCA on the ROM based setup utility (it doesn't look like it to me from the docs).

Thanks!
Uwe Zessin
Honored Contributor

Re: Subject: Assigning disk inner and outer halves to LUN

The SmartStart CD-ROM includes ACU which gives you much much better control over the SmartArray controller than RBSU.
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