Storage array to host boot disks for vPars

[Ninad_1]

Hi All,

I need your help in understanding and determining which array I should select to host the boot disks for multiple vPars. I am planning to have the following configuration.
rp7420 - 2 cells in a single nPar. 4 vPars configured in this nPar.
I will be having 5 such rp7420 servers each having 4 vPars - Thus making a total of 20 vPars at the moment.
If I have to use SCSI attached storage which will host the boot disks, there should be a mirror for each boot disk - I think more suitable option will be to have boot disk on one array and mirrored boot disk on another array thus having one path from vPar to the boot disk on array1 and other path to mirrored boot disk on array2. Would this be a good design step ?
Can you suggest which storage option should I choose ?
How many such arrays will I require to cater to boot disks for the 20 vPars ?

Please suggest your views as well. How usually such a configuration would be designed ?

Please let know if any further details required.
Also would like to hear from you views on having SAN boot disks instead - any caveats in using SAN boot disks ? But request you to please answer my main query as well :)

Thanks,
Ninad

[Ninad_1]

Any help please ?? :(

Regards,
Ninad

[Torsten.]

Ninad,

here you can see the different array systems from hp:

http://h18006.www1.hp.com/storage/arraysystems.html

The MSAs may be to small to meet your needs. If you want to have very high performance and very high availibility have a look at the XP array.
Another (perhaps cheaper) option is the EVA family. http://h18006.www1.hp.com/products/storageworks/eva/index.html
I would have a closer look on that.
In all cases you can use the array as a boot device.

[Ninad_1]

My problem is I am not able to understand which option should I select, hence I started this thread. I wanted some guidance in selecting the array.
I have gone through the storage array options. What I was really looking at was which array I should choose which can host the boot disks for the vPars such that each server will have multiple paths to the boot disk OR paths to a boot disk and mirrored boot disk on seperate arrays - if that would be a better option. I am really keen to understand how I should approach and what I should select.
OK , let me tell my analysis.
If I select MSA30MI which is a multi initiator with 4 I/O ports - 2 such MSA30MIs will be used to host boot disks for 4 vPars.
MSA30MI#1 - boot disks for vPar1, vPar2, vPar3, vPar4
MSA30MI#2 - mirrored boot disks (Thru Mirror-UX) for vPar1, vPar2, vPar3, vPar4

Is this correct ? Does 4 I/O ports mean I can connect 4 different hosts/vPars ?
Can I have the mirror boot disks on 2nd MSA30 for the same 4 hosts/vPars?
In this way I will require 2 MSA30MIs for every 4 vPars - thus will require 10 MSA30MIs for 20 vPars ????
Is this an efficient design at all ?
Or I should select any other array ? why ?

Gurus Please guide.

Thanks,
Ninad

[Torsten. · Accepted solution]

Ninad, the MI module is dividing the MSA30 in 2 parts, the left and the right group of disks. Normally you would the first server to connectors 1A and 1B, the second to 2A and 2B and mirror from left to right.
IMHO it's also a good idea to mirror 2 MSAa (e.g. first left side to second left side).

But if you share the BUS between 2 vPARS and boot from this BUS, you *cannot* preserve the boot disk for one partition by the second. You may (by accident) boot 2 vpars from the same disk - 2 crashed systems will be the result.

For your purpose an EVA (or XP) will be the best solution, because it is fast, it is safe (RAID1 or 5), you can have multiple pathes and it is secured (you present the LUN only to one vPAR).

[Ninad_1]

Torsten,

I would request you to answer my following questions.
Do you mean that I should use one MSA30 MI for hosting boot disks for 2 vPars,
thus I will require 10 MSA30MI disk enclosures for 20 vPars - right ?
Q1) Is this a good enough option

The other option of having EVA/XP for boot disks - LUNs from XP LDEVs.
Q2) So are you suggesting booting off SAN (FC) and not booting through SCSI attached array ?

Do you have the above scenarios at your end SCSI boot? SAN boot? In designing new systems, what do you use - booting off SCSI attached enclosure OR SAN boot disks. I am not able to understand and decide - between the much familiar SCSI boot method and SAN boot method which brings with it few problems or rather a bit tedious ways during recovery etc.
Please provide your advise in each case and what would you suggest ? Also ans to the Qs.

Thanks,
Ninad

[Torsten.]

I would never boot a server from a shared SCSI bus.

If you want to have dual pathes and mirrored disks, you have to calculate 1 MSA30 per vPAR (mirror left to right or one half from first MSA to one half of a second).

Thats why a SAN boot will be the better option. There is no problem in doing this.
More information:

http://docs.hp.com/en/7408/HPUXSANBootWP_final_v2_update.pdf

[Ninad_1]

Torsten,
OK I understand now that I need 2 MSA30 for 2 vPars thus 20 MSA30 s for 20 vPars.
In that case is it really required to have MSA30 MI - wont just MSA30 DB suffice ?

Do you have similar configuration SCSI as well as SAN boot ? Please tell me how it is at your end.

Has anyone got similar instance as above discussion ?
Anyone using SCSI boot for config similar to above requirement ?
Anyone using SAN boot for config similar to above requirement ?
Has no one configured similar configuration ??

Thanks,
Ninad

[Torsten.]

If you don't need shared busses, you don't need the MI module. The DB module is enough.

The question is, where will be your data?

If your data is already on the SAN, I would not get so many MSA30 and put only 2 disks for the OS in it. Doesn't make sense to have 20 boxes and 40 disks.

Another option are the "small" arrays MSA1000 and MSA1500. Because it was introduced as a "single controller" array for HP-UX, I would take at least 2 of them and mirror. Since a short time the MSA1500 is able to work active/active with 2 controllers for HP-UX.
I'm not sure if there is enough performance to deal with 20 OS instances.

Anyway, IMHO an EVA or XP (if you have the budget) is the right choice.

[Ninad_1]

Torsten,

Yes I would be having seperate storage arrays for data. could be some XP/EVA or HDS NSC55 array.
So when you say EVA or XP array for boot - arent you talking of SAN boot?
Then why not use the same array that I will use for data ?

BUT - wont the outage on the storage array cause outage on all the servers having boot disks on this array ? Is it recommended to have such a design ? Wont SCSI array for each vPar help in -
only affecting servers using the SCSI array only instead of affecting all servers using the same boot array incase of SAN.

Do you have such a configuration ?


Thanks,
Ninad