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Disks in XP arrays

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Ninad_1
Honored Contributor

Disks in XP arrays

Hi All,

I have xpinfo output for one of the XP256 arrays connected to a HP-UX 11.00 server.
Sample displayed below (Only relevant fields displayed)
/dev/rdsk/c33t0d0 XP256 CL2A 00:00 14014 RAID1 1-1
/dev/rdsk/c53t0d1 XP256 CL1A 00:02 14014 RAID1 1-1
/dev/rdsk/c33t0d2 XP256 CL2A 00:04 14014 RAID1 1-1
/dev/rdsk/c53t0d3 XP256 CL1A 00:06 14014 RAID1 1-2
/dev/rdsk/c33t0d4 XP256 CL2A 00:08 14014 RAID1 1-2
/dev/rdsk/c53t0d5 XP256 CL1A 00:0a 14014 RAID1 1-3
/dev/rdsk/c33t0d6 XP256 CL2A 00:0c 14014 RAID1 1-3
/dev/rdsk/c53t0d7 XP256 CL1A 00:0e 14014 RAID1 1-3
/dev/rdsk/c33t1d0 XP256 CL2A 00:10 14014 RAID1 1-4
/dev/rdsk/c53t1d1 XP256 CL1A 00:12 14014 RAID1 1-4
/dev/rdsk/c13t0d0 XP256 CL1E 00:14 14014 RAID1 1-5
/dev/rdsk/c73t0d1 XP256 CL2E 00:16 14014 RAID1 1-5
/dev/rdsk/c13t0d2 XP256 CL1E 00:18 14014 RAID1 1-5

Raid grp Disk Mechs
1-1 R107 R117 --- ---
1-2 R127 R137 --- ---
1-3 R100 R110 --- ---
1-4 R120 R130 --- ---
1-5 R106 R116 --- ---

Now my questions are
1. Are the disks shown in Disk Mechs correspond to actual physical disks in XP array ?
2. Why is it that the alternate disk groups are having 2 and 3 CU:LDEVs - why not same number ?

I am aware command view is used to get info on XP arrays and only the LUNs made visible to the server are visible through xpinfo. But I do not have access to command view - with this limitation can anyone please provide help on the queries.
The disks are 36 GB disks and each LUN is OPEN-8*2 (14014 MB).
Please let me know if anything else is requried.

Thanks,
Ninad Date
14 REPLIES
Alzhy
Honored Contributor

Re: Disks in XP arrays

1.) Yes xpinfo is quite accurate but it should match the firmware code on your XP.. only latest xpinfo though can understand 7+1P or 4+2P configs.

2.) That's how your LUNs were presented.. ask your storage admin.

Hakuna Matata.
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Nelson,

Thanks for your guidance.
Only one thing - I had read somewhere that the 7+1P or ... are available with latest firmware for XP1024 , but not for XP256.
Please can you confirm.

Thanks,
Ninad
Peter Mattei
Honored Contributor

Re: Disks in XP arrays

Yes you are right!
RAID5 (7&1) is supported starting with XP128 / XP1024 and of course the XP1000 / XP12000.

Your configuration:
RAID Group 1-1 is RAID1 and consists of physical disks R107 and R117.
It presents 3 LUNs of 14GB to your HP-UX server:
/dev/rdsk/c33t0d0 XP256 CL2A 00:00 14014 RAID1 1-1
/dev/rdsk/c53t0d1 XP256 CL1A 00:02 14014 RAID1 1-1
/dev/rdsk/c33t0d2 XP256 CL2A 00:04 14014 RAID1 1-1

Easy as that
Peter
I love storage
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Peter,

Yes it seems as simple as you explained. But what I am not able to understand is that why the alternate raid-groups are having 2 and 3 CU:LDEVs ? why not 3 in all raid groups or why not 2 in all raid groups ?
Also as per my understanding 36 GB disks are used. If you use 36 GB disks in a RAID1 we will have 36 GB usage apce in which I can create 2* 14GB LDEVs and still have 8 GB space unused. Also I cannot have 3 * 14 GB LDEVs in a raid group using 2 disks and RAID1. So how are 3 LDEVs possible in one RAID group ?
The only way I can see is that if I can combine 2 raid groups then I can have 5 LDEVs of 14 GB amongst them thus only then it may be possible to see 2 LDEVs in one raid group and 3 LDEVs in next raid group. But then how does the xpinfo show the disk mechs as being different for both the raid groups - one raid group should show all the 4 disks as it is spanning across disks - if this is possible at all in the first place.

Please can anyone help on the above. How does it all work in reality. I have not worked on XP arrays, I am trying to check if any disks are unused and can be made available to be shifted to some other array.

Thanks a lot,
Ninad
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Hi,

Any help please.

Thanks,
Ninad
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Hi Gurus,

Any help please .

Thanks,
Ninad Date
Peter Mattei
Honored Contributor

Re: Disks in XP arrays

Hi Ninad
I was out yesterday!

Well, I can actually not fully understand your configuration!
Can you provide a serial number of your XP256? I need the last 5 digits.
I can then have a look at your HW configuration in the HP database.

I assume your LUNs are not equal.

Cheers
Peter
I love storage
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Hi Peter,

Thanks a lot.
The serial no - last 5 digits is 55289 for the XP256 array.
Please let me know, If you want I can provide the full xpinfo output as well.

Thanks very much,
Ninad
Peter Mattei
Honored Contributor
Solution

Re: Disks in XP arrays

Ah, I see
Your 36GB Disk Groups each are configured with 5x Open-8

Group 1-1 look like that
CU-LDEV 0-00 0-01 0-02 0-03 0-04
Group 1-2 look like that
CU-LDEV 0-05 0-06 0-07 0-08 0-09

In your XPINFO output above you only see the staring LDEV of a LUSE.
It looks like your LUSEs consist of
LDEV --------- Disk Group
0-00 + 0-01 -- 1-1
0-02 + 0-03 -- 1-1
0-04 + 0-05 -- 1-1 and 1-2
0-06 + 0-07 -- 1-2
0-08 + 0-09 -- 1-2
etc.

I hope this clears it up!

Cheers
Peter
I love storage
Alzhy
Honored Contributor

Re: Disks in XP arrays

Ninad,

Peter is correct.. some of your RAID groups have LUSE (LUN expansion) -- which I think you]ve mentioned earlier youve LUSE*2.. you can check this out via SCSI inquiry (EMC's inquire command or other SCSI inquiry tools). I do not think xpinfo does justice and portrays what LDEVs have been LUSEd.

HTH.
Hakuna Matata.
Ninad_1
Honored Contributor

Re: Disks in XP arrays

You are simply great Peter. Thanks a lot for all your help.
I got it. That solves the whole riddle I have been trying to understand for quite a while.

Thanks so much.
Ninad
Alzhy
Honored Contributor

Re: Disks in XP arrays

Ninad,

BTW, do not misconstrue LUSE'ing ldevs as a performance boost -- LUSE'ing ldevs is a means to carve up bigger LUNs. Note also that LUSEs are simply concats of your standard LDEVs.

I rarely use/request LUSEs. I Always use the host's volume manager to carve up bigger and better performing storage units (volumes?lvols) by striping them -- which is the best practice for XP/Hitachi arrays. (Yes XP arrays are rebadged Hitachi arrays).
Hakuna Matata.
Ninad_1
Honored Contributor

Re: Disks in XP arrays

Hi Nelson,

OK. Just can you let me know is there limit to the LDEV size due to which its required to configure LUSE to get bigger LUNs ? - what is the limit ? What is the disadvantage of LUSE over normal LDEVs?

Thanks,
Ninad
Peter Mattei
Honored Contributor

Re: Disks in XP arrays

Under HP-UX I preffer using more LUNs/LDEVs and put them in a LVM Volume Group.
Advantages:
Performance - Each LUN has an IO queue
Flexibility - You can add LUNs concurrently

The only disadvantage is that you have to manage more device files.

LUSE has two goals:
Keep the numbers of LUNs low for larger volumes (Under Windows you need it if you need a big LUN)

You can build LUSE from 2 to 36 LDEVs.

To the Open-LDEVs

For the XP256 the following sizes are available:
OPEN-3 2.4 GB
OPEN-8 7.3 GB
OPEN-9 7.3 GB
OPEN-E 14.5GB
OPEN-K 1.8GB
OPEN-L 36.4GB
OPEN-M 47.1 GB


Also see the XP maual here
http://h20000.www2.hp.com/bc/docs/support/SupportManual/c00264181/c00264181.pdf


Cheers
Peter
I love storage