topic Partitioning disk drives on a SMARTArray 5300A in Operating System - OpenVMS

Partitioning disk drives on a SMARTArray 5300A

Andrew Rycroft1 — Thu, 30 Jun 2005 02:21:40 GMT

Hi,

I have a KZPDC-BE, 2 channel RAID SMART array controller running in an ALphaServer DS10. At console mode I can go into the the controller bios and create logical drives. These logical drive consist of a number of physical drives, e.g. 5 72.8GB disk drives can be combined into a logical RAID 5 RAIDset.

Is it possible to then partition this drive into a number a separate partitions/LUNS that will be visible to OpenVMS as separate disks ?

Thanks
Andrew

Re: Partitioning disk drives on a SMARTArray 5300A

Uwe Zessin — Thu, 30 Jun 2005 02:38:12 GMT

No, the SmartArray controllers work a bit different.

You bind several physical disk drives together to form a disk array. Then you create one or more logical disks inside the array. These will appear as separate devices on OpenVMS.

Re: Partitioning disk drives on a SMARTArray 5300A

Veli Körkkö — Thu, 30 Jun 2005 03:30:32 GMT

actually yes. The problem is just sort of egg and chicken style. You can actually configure your controller using at least two methods.

First one you know already, i.e. from SRM console using so called ORCA.

>>> run bios pya0

With this method you can only create some storagesets and then assign a lun to the whole set. No partitioning possible!

Another method is to install VMS, TCPIP, Motif first. Configure everything, then install WBEM aka Insight Manager agents.

Suppose you have either VMS V7.3-1 or VMS V7.3-2. then you would use WBEM V3.0-36 kit.

And last but not least you will need ACUXE addon which will then allow access to SmartArray 5300A via web browser thrhough ACUXE / WBEM.

And now you can configure the array any way you wish.

So, I would install VMS etc on to a "pure scsi disk" (i.e. onto one attached to ordinary scsi adapter) and then configure the KZPDC and then move finally stuff from the scsi disk to the logical disk behind KZPDC

I would however leave somekind bootable env on a scsi disk since there would no nice way to manage KZPDC now using SRM console/ORCA

Of course one could have two full disks dedicated to VMS op sys as RAID 1 and just partition the data disks...

Btw, I did this for one of my customer so this is just not theory but actually true and tried.

_veli

Re: Partitioning disk drives on a SMARTArray 5300A

Uwe Zessin — Thu, 30 Jun 2005 04:04:12 GMT

The "No" refers to the ability to partition a logical disk as confirmed by you.
I didn't see the configuration process as a question, but like your additional info.

Re: Partitioning disk drives on a SMARTArray 5300A

John Gillings — Thu, 30 Jun 2005 22:21:27 GMT

Andrew,

RAID5 was a moderately good idea when disks were small and expensive. Now that they're large and cheap, it's a very bad value proposition. Reduced overall performance for moderate improvement in resiliancy, extremely poor performance while recovering.

Partitioning is for operating systems that can't handle large volumes. Again, poor performance (head contention between volumes gives you worst case seek times) and a DECREASE in resiliancy - lose one volume, lose them all.

Combine the two and you have the absolute WORST of all worlds. Performance isn't anywhere near potential for the hardware and there are too many cross dependencies.

Add one extra drive and form three RAID 1 sets (or even better use host based shadowing across two controllers). Performance is good as there is no contention across logical volumes, data resiliancy is MUCH better and does not suffer too much in recovery.

Please take a VERY careful look at your options and objectives before considering RAID 5.

Re: Partitioning disk drives on a SMARTArray 5300A

Uwe Zessin — Thu, 30 Jun 2005 23:16:49 GMT

RAID-5 is still a good value proposition today. Disks have become faster and more reliable while the fight to save money has become harder, at least in this part of the world.
Cusomers can save disk bays which sometimes can decide for one or more disk drive enclosure and on some arrays there is additional cost per raw capacity. One disk more or less can decide on another license jump.

I know that one should not try to squeeze down to the last disk, but that's the way it works in many environments.

> Partitioning is for operating systems that can't handle large volumes.

Right, like operating systems that can't deal with volumes > 1 TeraBytes ;-)

It surely is impressive to talk about performance, but most systems don't require that extreme values anyway.