Autoraid - How to define new LUN?

[Yogeeraj]

Hello experts,

i would like to use the remaining diskspace on my autoraid.

When i check the status using SAM, it tells me that there are 2474 Mb of "Unallocated physical capacity".

Could u please guide me on how to proceed and also if possible tell me if it is wise to use the remaining disk space. Will this result in any drop in performance?

thank you very much for a reply

Best Regards
Yogeeraj

PS. I am attaching the SAM report on my Autoraid. (12h)

[Bill McNAMARA_1 · Accepted solution]

http://www.hp.com/essd/model12H_autoraid_tool.html

Your performance will decrease only when data starts to fill up the luns on the autoraid, not when the luns are defined.

Note that in order to keep your autoraid at peak performance only use 50% of you maximum disk space. This will mean that effectively all the data on the autoraid will be stored in raid 1/0 which is much faster than raid 5. You will be in raid 5 if you have a 100% full autoraid. 10% of the data will be in raid 1/0. As the calcn gets difficult see the link above.

Also look areound that site for some perf tips.

However, your real perf benefit comes from correctly configuring lvm. Make sure you balance your io across two controllers on seperate busses.

PS: I'll have a look at your attachment after I post this..

Later,
Bill

[Bill McNAMARA_1]

Go ahead and create the lun, you've got hotspare on which is ensuring data space in raid 1/0.

If you see perf decreasing you can simply add a new disk.
However, since
Auto-Include: Enabled
you will want to do this later at night, because adding a new disk will cause the array to shift data from R5 to R1/0 which means a lot of disk io.

The unallocated space is not really unused. That space is used for 1/0.
Logical Drives: 12888 Mb
out of a total space:
Total: 24575 Mb
including hotspare disk space:
Active Spare: 4095 Mb

This means your data is effectively all in R1/0
Data Redundancy: 5118 Mb
is nearly 50% of the lun size.
(Sometimes it's better to be in R5)

Use command line for more detail:

arraydsp -a JK447218043R
(man arraycfg for disk/lun)
(man arraymgr for cntrlr stuff)

You seem to have only 2 PS.
That means the array will shutdown should one fail... is that okay by you? Note that the array shutting down means that the array shut's down well, by blocking io, finishing io and rewriting maps but your f/s on the server side will drop not umount... so be warned.

Also:
from arraydsp -c JK447218043R
figureout your f/w level of the controllers. Somethimes a rebuild can be real slow with older firmware.. although your disks seem only 4G so it won't be all that long unless you move up to 9's 18's or 36's or any of the 10krpms later on..

Have fun with it, and remember it's the hardware wiring of the scsi.. two busses into the autoraid (40MB/s not 2 controllers on one bus of 20MB/s) that really give the main perf benefit. It makes more sense to get that right. Then making sure that LVM is configred correctly make it all work.....


Later,
Bill

[Yogeeraj]

Thanks for the replies BILL

A few things not so clear:
1. The 12H has only 2 power supplies. There is room for expansion in it. I wanted to confirm if it is really true that if one of them fails, the autoraid will go down!!
2. what is the thing about the 2 controllers and one bus? During our installation, we were told that one should be primary and the other secondary sitting back and which will be activated in case of a failure...
3. We have already bought 2x18 GB (10K rpm)Hard disks and have been told that we can use it without replacing the old fans with new high speed ones... What do you think?
4. To configure the new LUN, is there another way than manually interacting with the Autoraid front panel? (could u send me the steps please)
5. Is it true that we have a limit on the number of LUNs that can be created on the AutoRaid?
6. Is it possible to share the autoraid between 2 systems? (e.g. my K250 and L1000)


thanks you for a reply
Kind Regards
yogeeraj

[Bill McNAMARA_1]

1. The 12H has only 2 power supplies. There is room for expansion in it. I wanted to confirm if it is really true that if one of them fails, the autoraid will go down!!
> It will shutdown correctly.
> The autoraid can function on
> one, but would prefer not to.
> so it will protect itself by
> executing a proper array shutdown.

2. what is the thing about the 2 controllers and one bus? During our installation, we were told that one should be primary and the other secondary sitting back and which will be activated in case of a failure...
> No, use both controllers at the same time.
> put some io through one and some through
> the other.
> Your cableing should look as follows:
> 8/8 ----- Controller X
> |-
> 8/12 ---- Controller Y
> |-
>
>not
> 8/8 ----- X
> |
> |- Y
> where 8/8 and 8/12 are scsi cards
> in your host (this is a k example)
> each scsi card can throughput
> 20MB/s on it's bus.

3. We have already bought 2x18 GB (10K rpm)Hard disks and have been told that we can use it without replacing the old fans with new high speed ones... What do you think?
> If your fans are 10K capable
> you can tell because the 10K
> fans have a plastic bubble.
> the 7200rpm drive fans
> have a sticker.
> Last I heard you need 10Krpm
> fans for 10krpm drives.
> load the drives as close to
> fans as possible. Leave the
> slots near the PS free..
> unless you got all 12 drives.
> load top to bottom, left to right.

4. To configure the new LUN, is there another way than manually interacting with the Autoraid front panel? (could u send me the steps please)
> create lun 2 size 500 M
> arraycfg -L 2 -a 500
> or 5 Gig
> arraycfg -L 2 -a 5G
> delete lun 2
> arraycfg -L 2 -d

5. Is it true that we have a limit on the number of LUNs that can be created on the AutoRaid?
> maximum of 8
> in your ioscan it'll show up
> as d0 to d7
> you'll see it through the
> controller.
> the controller is the target t3 for example
>

6. Is it possible to share the autoraid between 2 systems? (e.g. my K250 and L1000)
> You can access lun 1 on the k
> and lun 2 on the L
> BUT, if you don't have MC/SG
> you can't/shouldn't access
> lun 2 on both..
> because remember you can
> pvcreate from the L and not
> want to have done that on the K
> there is a lock that you may
> consider in arramgr to stop
> one system from configuring
> the array. (nothing to do
> with lvm.. you can still pvcreate -f, vgscan could cause trouble
> if you're not careful too.)
> man arraymgr for more..
> i never did that so can't comment..
> but i'd be fine once you remember
> to access odd luns from the K
> and even ones from the L
> for example..

Later,
Bill

[Bill McNAMARA_1]

Forgot that spaces are removed from reponses:

> 8/8 ----- Controller X
>>>>>>>>>>> |-
> 8/12 ---- Controller Y
>>>>>>>>>>> |-
>
>not
> 8/8 ----- X
>>>>>>>>>>> |
>>>>>>>> |- Y

Got it?

Dont forget the points!

Later,
Bill