topic Re: SAN disk visible to all servers in Operating System - HP-UX

SAN disk visible to all servers

Coolmar — Tue, 30 May 2006 10:15:07 GMT

When I am assigned some SAN disk from the storage group, I get those disks as well as some disk from other servers. I then have to do a diskinfo -v to find out which disk is mine. I definitely should not be seeing/assigned disk belonging to other servers but am told that it has something to do with the brocade switches. Anyone heard of this?

Thanks!

Re: SAN disk visible to all servers

Christian Briggs — Tue, 30 May 2006 10:21:15 GMT

Sally,
It sounds like you don't have any zones setup on your switch and / or what ever you are using for masking (on the array) isn't configured properly.

Re: SAN disk visible to all servers

Rick Garland — Tue, 30 May 2006 10:23:02 GMT

It could be how the zoning is configured.

The Brocades can do zoning to limit what system sees what hardware resources. If there is no zoning in place then all systems will see all hardware resources.

Can be a management nightmare and can increase the risks that a mistake will be made. Typically a mistake caused by human error.

Re: SAN disk visible to all servers

Zinky — Tue, 30 May 2006 10:36:05 GMT

Yep, you seem to have zoning or hostgroup configuration issues alright. What linf of SAN disk/arrays do you have?

Re: SAN disk visible to all servers

sathish kannan — Wed, 31 May 2006 03:52:25 GMT

Sally,

You need to do Zoning from Brocade switch level which prevents seeing other Storage components level. This will avoid discovering unwanted targets to be visible to the host. I believe you have open fabric in your SAN environment.

You haven't mentioned what type of storage you use?. Every storage vendor provider provides masking softwares to restricts the devices to be accessed by individual host.

Review both zoning and masking ASAP and implement them.

Regards
Sathish

Re: SAN disk visible to all servers

Coolmar — Wed, 31 May 2006 06:45:45 GMT

Our SAN is Hitachi3. The storage group is in charge of the switches, SAN, etc. I am just the HP-UX Admin who requests disk. The problem is that when I request disk, I get my disk as well as disk from other systems and if I am not very very careful I could accidentally wipe out another systems lv. It is a pain and I really should not see other systems' disk but all the storage group says is that this is the way the brocade switch works - they feel there is a bug or something I guess.

Re: SAN disk visible to all servers

Zinky — Wed, 31 May 2006 07:41:59 GMT

Ask your HItachi person if he even knows Zoning, LUN Masking, etc. If he does not - then - your "SAN Administrator" simply needs to be fired - period.

Re: SAN disk visible to all servers

Michael Steele_2 — Wed, 31 May 2006 08:25:13 GMT

There's a lot to zoning so don't just jump into. The HPA ( fibre channel adaptors ) are the bottlenecks between you and your disk array.

I think the usually you'll assigne one zone per HPA. And you definitely should have two HPA's per server. This is for redundency.

However, maximizing your HPA connections on your server is how you overcome any bottlenecks. Its the old comparison of a fire hose and a garden hose. The fire hose can deliver more water.

But be consistent with one zone per HPA since this will still give you unique HW addresses.

Re: SAN disk visible to all servers

Rick Garland — Wed, 31 May 2006 08:35:48 GMT

The Brocades are able to do zoning. And as previously mentioned there is a lot to setup and configuration of zoning.

You are definitely correct. The management of disks presented to systems needs to be throughly documented and kept up to date - always!

If you pvcreate a disk that is in use for another system you are correct, you have a problem.

As a last line of defense, ensure the backups are good. If the unthinkable happens you will at least be able to restore.

Re: SAN disk visible to all servers

Don Mallory — Wed, 31 May 2006 08:45:55 GMT

Presentation management is what you are looking for.

On the HP Virtual Arrays it's licensed per terabyte of disk ($10k / Year if I recall) and called Secure Path (not to be mistake with Secure Path Manager).

On the HP EVA arrays, there's a little button that says, "Present".

You are probably seeing the LUNs because your storage team has determined to use Port Zoning instead of WWN (world wide name) zoning on their switches. It's technically more secure as you can spoof a WWN, but you can't spoof a physical port. It's also easier to manage.

On the other hand, it means that your host sees the array, all of it.

In our case, we have Compaq EMAs, (with presentation management), HP EVAs (with pres. mgmt.) and our VAs.. without, because it's just too expensive. So, you have to find ways around it.

Ways around it.

If the array is Active/Passive, as opposed to Active/Active. Secure Path Manager will mask all of the additional paths. However, be careful; when you install it, it will change all of your disk paths the first time, so vgexport to a map file, and re-import later.

Map your LUNs. For our VAs, we keep a spreadsheet, a map of which LUNs point to which hardware path. There is a defined hardware path (after the FC adapter) that you can find in an ioscan.

Two useful references for understanding this are:

http://www.hp.com/hpbooks/prentice/chapters/0130102229.pdf

The other link is broken, I'll attach it.

Also of note, if it's a new LUN, on an ioscan, the newest LUN will have the highest instance number (column I), look for your two (for single HBA on your host) or four (for dual HBAs on your host)

Good luck,
Don

Re: SAN disk visible to all servers

Coolmar — Wed, 31 May 2006 08:50:42 GMT

When I ask for disk, I have to supply my WWN..so I believe that is the way the SAN is running/setup.

Re: SAN disk visible to all servers

Zinky — Wed, 31 May 2006 08:56:23 GMT

Sally - I hope you did not fire your Storage Admin (yet)..

What kind of Hitachi Array are you using? If it's anywhere below an HDS9980 - then it is possible you do not have yet LUN security(Presentation security) via the concept of HostGroups -- so that your SAN zones will consist of the Switch Port(s) and the Server's HBAs that have access to that port(s). LDEVS/LUNS are presented on older HDS Arrays (and HP XP too) on a per CHiP port basis going to the switches. So that explains why all servers on a zone sees all LUNS that are presented.

A spreadsheet, and tools to ascertain on a server which LUNs it should own and religiously maintaining it is the key here.

Also, you may want to move to VxVM as it offers better avoidance on overwriting LUNs that are already in use elsewhere.

Keep your Storage Admin --

;^)

Re: SAN disk visible to all servers

Coolmar — Wed, 31 May 2006 09:01:55 GMT

Hi Nelson....the model is a 9960.

Re: SAN disk visible to all servers

Zinky — Wed, 31 May 2006 09:05:42 GMT

aha... same as ours!

HDS9960 == XP512.

I don't think even HP was able to implement the concept of HostGroups for heterogenous connections and LUN security on this model.

It started I think with the XP128 (9980V) and the XP1024 upwards (HDS 9980/9990 -> XP12000).

Re: SAN disk visible to all servers

Coolmar — Wed, 31 May 2006 09:08:51 GMT

I think Nelson might be right with his assessment. Thanks everyone!