topic Re: Securepath vs LVM in Operating System - HP-UX

Securepath vs LVM

Shift Support — Sun, 04 Sep 2005 14:07:48 GMT

Our environment is UX 11iv2 booting from an EVA3000. Two questions:

1)LVM seems to handle multiple paths to the same disk. So why install Securepath? Is it safe to run with LVM only?

2) If you install Securepath, Ignite-UX's recovery options do not work (make_net_recovery). System crashes when trying to boot from the restored disk. Anybody run into this?

Re: Securepath vs LVM

Sameer_Nirmal — Sun, 04 Sep 2005 18:20:42 GMT

1) You are right in saying LVM handles Multiple paths to the same disk as Securepath does.

In EVA there are 2 HSV controllers working in Active/Passive Mode. That means a Vdisk/LUN from you host will be active only on one of the controlles. Both controllers can't server the same LUN at the same time.

Now in case of one of the controllers failure, the LUN could be accessible from the another controllers. From HP-UX point of view , there has to be failover to the second controller path and it doesn't support the failover of its own ( unless you have LVM LV links). Hence SecurePath software is required to be installed on the host , so it will take care of the failover to another controller path and you don't have a situation as not able to access the LUN.

As far the failover to different path is considered , LVM could be used in place of SP. Remember SP provides you other feature apart from path redundancy is load balancing.
This load balancing ensures getting good I/O throughput as you are using both FPs on EVA controllers. Thats why HP recommends to use SP with EVA.

2) Youe second question is quite interesting.
I belive there should not be a problem using Ignite-UX with EVA for restored bootable LUN.

Can you provide more details about the crash??

Re: Securepath vs LVM

Shift Support — Sun, 04 Sep 2005 18:43:47 GMT

Thanks for the information. The Ignite issue is documented here, unfortunately I did not see it we tried a test recovery.
If I read this correctly, if you put Securepath on then regardless or whether you boot from local or EVA disk your going to have problems with Ignite's recovery.

http://docs.hp.com/en/5990-8153/ch04s04.html
Compatibility

The Secure Path V3.0E is not supported for Ignite-UX type of installation or recovery
for the following two reasons:

When the Secure Path V3.0E is installed on a system, the hardware address of all EVA disk
luns change once the product is installed. During the recovery process, if LVM volume
groups exist on the EVA array, importing those volume groups may fail.
Further, if the boot disk resides on an EVA array, the system will fail to boot and is
most likely due to an LVM configuration failure panic.

The Secure Path V3.0E is not included in the install kernel and is not part of the
core HP-UX Operating System, so Ignite-UX is unable to support its use.

Re: Securepath vs LVM

Sameer_Nirmal — Sun, 04 Sep 2005 19:21:58 GMT

Yes you are right.

I didn't know about the SP in-compatibility with Ignite-UX. SP V3.0E is providing EVA Boot and Dump support only. Let's hope to have solution on this from HP in near future.

Re: Securepath vs LVM

Shift Support — Mon, 05 Sep 2005 12:18:50 GMT

Does anybody know if HP approves running UX without Securepath on an EVA, given the recovery option with securepath installed is a rebuild.

Re: Securepath vs LVM

Ranjith_5 — Mon, 05 Sep 2005 12:23:15 GMT

Hi Sandhu,

HP recommands running EVA with Securepath.

Regards,
Syam

Re: Securepath vs LVM

Shift Support — Mon, 05 Sep 2005 13:20:38 GMT

Any ideas on how to do a recovery if you have installed securepath and Ignite make_net_recovery does not work?

Re: Securepath vs LVM

Leif Halvarsson_2 — Mon, 05 Sep 2005 13:37:35 GMT

Hi,

I run into a lot of trouble when trying to boot from SAN, using SP 3E. For the moment, i do SAN boot, using single path. It works OK (also together with Ignite) but, of course failower is not possible.

An (possible) alternative to SP/LVM is VxVM which , as I have understand, has multipathing built in. But, I am not sure if EVA is supported yet.

Re: Securepath vs LVM

Shift Support — Mon, 05 Sep 2005 14:10:54 GMT

Seems like the best solution would be boot locally. Then you don't run into the recovery issue due to securepath.

Anybody using this solution?

Re: Securepath vs LVM

Bill Costigan — Tue, 06 Sep 2005 08:04:13 GMT

You can use LVM on the eva3000 without securepath, however you cannot use the failover feature.

Typically, there are 4 paths (device files) for each LUN, 2 to one controller and 2 to the other. If you create an VG and only add two device files for the same controller LVM is happy. The two paths should be to the active controller not the passive one.

One problems is that once SecurePath is installed it will prevent you from doing this because it converts all the eva paths from sdisk to hsx devices. So it's all or nothing, unless someone knows how to tell secure path to ignore some devices.

Re: Securepath vs LVM

Uwe Zessin — Tue, 06 Sep 2005 09:37:24 GMT

I don't understand why you want Secure Path to ignore a potential useful path on the EVA3000/5000?

Re: Securepath vs LVM

Bill Costigan — Tue, 06 Sep 2005 09:54:16 GMT

So you can boot from the SAN.

Re: Securepath vs LVM

Sheriff Andy — Tue, 06 Sep 2005 11:12:47 GMT

We have an EVA 5000. We have two internal boot disks on our servers & use ignite with no problems.

I would really recommend not using your SAN disks as your boot disks, just because of the very nature of the EVA.

We have had device files change on some of our production disks during reboots or ioscans. I would highly recommend having good mapfiles of your volume groups. Also get very familiar with your command view & spmgr display command.

Another thing, there is no way that I can think of without secure path to tell where a particular disk belongs on the EVA. You can get the World Wide Lun ID off of spmgr display, then make your comparisons to command view.

Hope this is of some help.

Re: Securepath vs LVM

Shift Support — Tue, 06 Sep 2005 12:04:34 GMT

Thanks to all for the feedback. Our solution is to boot from local disks. Use the EVA with securepath install only for the non-boot disks. Ignite works like a charm on the local disk.

Re: Securepath vs LVM

Shift Support — Tue, 06 Sep 2005 12:05:16 GMT

Use local boot disks.

Re: Securepath vs LVM

John Payne_2 — Tue, 06 Sep 2005 12:06:32 GMT

We run Securepath on our SAN connected machines, but I use Golden Images strictly (no recovery images). With the Golden Image, there doesn't appear to be issues having the Securepath software installed, but I also have vg00 on local disk everywhere, never on the SAN.

SecurePath will load balance traffic across multiple HBA's (if you turn the load balance on. 'spmgr sert -b on'), which makes a BIG difference on 2 of our DB machines...

Hope it helps

John