On Thu, 24 May 2007 22:27:07 +0200, luke wrote:

>I have p550 with 48RAM + 8CPU and 8 disks. I don't have RAID controller.
>My server has VIOS + 20-40 LPARs ... I mirrored VIOS on two disks.

Good.

>I have 6 disks 300GB for split to all 20-40 LPARs.
>What do you think how can I configure disks from performance point of view?

Regardless of your configuration you're going to have a very limited
infrastructure. Look at it this way -- assume 20 LPARs and six 15K
300GB disks. Each disk is capable (downhill with favorable winds) of
150 random I/O per second. 20 LPARs that gives 7.5 I/O per second per
disk per LPAR or, with 6 disks, 45 IOPS per LPAR. That's the maximum
rate. You shouldn't seriously consider running more than half that in
any sustained "production" situation.

Similarly, you're going to have to carve up memory and that leaves you
with about 2GB per LPAR. This may be enough -- I remember when
everything ran in 32K -- or it may not be. If it's not, you better not
even consider paging because, per the discussion above, this will die
on the vine.

You should look realistically evaluate your workload and determine if
this is a reasonable hardware configuration. If this is just an
experimental environment or for your own education, sure, it'll work.

>1. 3 disks in VG + 3 in mirror (save configuration)
>2. 6 disk in huge VG (if one disk wiil be failed I lost only a few
>LPARs, right?)
>3. 6 disk in VG with stripping (if one disk will be failed I lost the
>data, right?)

Logical volumes on the VIOS used as virtual disks cannot be mirrored,
striped, or have bad block relocation enabled. See
http://www14.software.ibm.com/webapp...ation/faq.html

Mirroring would have to be done by the Client LPARs.

-- David

Hi David,

Thank you very much for you reply.

[...]

>>I have 6 disks 300GB for split to all 20-40 LPARs.
>>What do you think how can I configure disks from performance point of view?
>
>
> Regardless of your configuration you're going to have a very limited
> infrastructure. Look at it this way -- assume 20 LPARs and six 15K
> 300GB disks. Each disk is capable (downhill with favorable winds) of
> 150 random I/O per second. 20 LPARs that gives 7.5 I/O per second per
> disk per LPAR or, with 6 disks, 45 IOPS per LPAR. That's the maximum
> rate. You shouldn't seriously consider running more than half that in
> any sustained "production" situation.
>
> Similarly, you're going to have to carve up memory and that leaves you
> with about 2GB per LPAR. This may be enough -- I remember when
> everything ran in 32K -- or it may not be. If it's not, you better not
> even consider paging because, per the discussion above, this will die
> on the vine.
>
> You should look realistically evaluate your workload and determine if
> this is a reasonable hardware configuration. If this is just an
> experimental environment or for your own education, sure, it'll work.
>
>>1. 3 disks in VG + 3 in mirror (save configuration)
>>2. 6 disk in huge VG (if one disk wiil be failed I lost only a few
>>LPARs, right?)
>>3. 6 disk in VG with stripping (if one disk will be failed I lost the
>>data, right?)

I didn't write that this p550 has 20LPARs but will be upgrade with
disks, too.

2xdisks 143 (15rpm) for VIO Server with mirror
5xdisks 300 (10rpm) for 20 LPARs. Four LPARs per one disks. Database was
installed on other server (with fast I/O).
1xdisk 300 (10rpm) for evenutally mirror for LPARs partition

> Logical volumes on the VIOS used as virtual disks cannot be mirrored,
> striped, or have bad block relocation enabled. See
> http://www14.software.ibm.com/webapp...ation/faq.html

Thanks. I didn't know it

By the way. In VIO server I can see option 'any partition can share this
disk' or something like that (I write from memory). How can use it? I
must configure GPFS and share vhost for LPARs?

Best,

Luke