HPUX and EVA securepath

[Mark Johnson_1]

We have recently purchased an EVA5000 and I am attaching various HPUX systems to it. Almost all of the systems that will utilize EVA disk have a single data path or HBA (they are test systems not designed for fault tolerance). My question is: Is securepath needed, desirable, optional in an HPUX/EVA environment. So far, HP9000 systems attached (zoned) to the EVA get multiple results. Sometimes the systems see one disk, sometimes they see one disk with two paths.

P.S. This thread has been moved from Disk to HP-UX > sysadmin. -HP Forum Moderator

[Ian Vaughan]

Howdy,
I would say that securepath is unfortunately still a necessity for HP-UX. On windows we now have MPIO to handle failover and on Linux we have SteelEye & Qlogic driver multipathing but on HPUX SecurePath is still the only choice.

As the EVA presents each LUN to both controllers and each controller is attached to both (you do have 2?) switches at least 2 versions of the same LUN will turn up even if you only have 1 HBA. It certainly makes things easier if you can only see 1 version of each Vdisk. Compared to how much the 5K cost the Secure Path LTU's are probably reasonable.
How about consolidating the test systems down into fewer boxes? If you have N & L-class systems rp3440's will wipe the floor with them in terms of tpm's and will probably work out cheaper compared with ongoing support costs. Slightly off topic but every little helps...
Cheers
Ian

[Mark Grossman]

Mark,
we run several HPUX L and A class test servers with only 1 HBA fiber card and no secure path software.
We do however hard zone these to only one fiber switch/one eva controller for both directions.
We have had no problems with this scenario.

Mark

[Alzhy]

HP-UX Single HBA connections to EVAs are fully supported by HP and I believe even documented very well.

For your Production Machines though with dual HBAs, you cannot get away without SecurePath if you want fault tolerance and load balancing (on the HBA level at least). Note that PVLINKS is not supported on EVA LUNs. Also note that DMP (in case you plan to use full VxVM) does not also work with EVA paths (yet).

[Mark Johnson_1]

All Ports on the EVA are connected to one fabric. Controller A, port 1 and 2, Controller B, port 1 and 2. So which of the possible four ports do I want my HBA to see (zoned).

[Mark Grossman]

Mark,
pick one - your choice.
We just manually try to balance our single HBA servers, and the port to use to the eva.

Mark

[Mark Johnson_1]

Mark,
How do you assign a disk on the EVA to a port. I understand how to assign a disk to a controller.

Thanks

[Mark Grossman]

Mark,
I guess I'm a little confused now.
Does this look correct?
1) we plug our single HBA into Port 4 of switch 1. Port 1 goes to Cntrl A, and 2 goes to Controller B.
2)we zone it so port 4 only uses port 1 to communicate with the eva only thru port A.
3)we create a vdisk on the eva and present it to the host with this HBA card.
4)we ioscan -fnCdisk and insf -e on the hpux host.
We should now see the disk and the device file and it shouldnt change.

Mark

[Thayanidhi]

Hi Nelson,

Are you sure "PVLINKS is not supported on EVA LUNS" In some places I used PVLINKS over EVA LUNS. So for there is no issues. I installed patches which are recommended for SP, but not installed the SP. Any official document from HP, that the SP is must for EVA LUNs.

Thanks
TT

[Uwe Zessin]

Then you have just been lucky. PVLINKS requires active/active paths to a virtual disk, but that is not a feature of the EVA3000/5000. Have you really, really tested failovers between all 4 paths?

Here is a pointer to an old document, but it is still valid recarding PVLINKS:
http://h18000.www1.hp.com/emea/presalessupport/downloads/EVA_HP-UX.pdf

[Leif Halvarsson_2]

Hi,

Secure Path is not necessary if you have zoned your switch so that each HBA only can see one controller (single path). There is one exception. SAN boot from single path is not supported (but is supported using Secure Path). I don't know why, i can see no difference with booting single path SAN boot and booting from a single local disk (which is supported).

I have some test servers, configured for single path SAN boot and, have not yet seen any problem.

[Uwe Zessin]

It's possible that the bootstrap code is missing the necessary code to bring a virtual disk online should it be active on the other controller.

[Mark Johnson_1]

I have two ports per controller card, so four ports all together. Do the controllers primarily chose only one port that the HPUX hosts can see data on. If so, which port is it? Port 1 or Port 2? Like I said earlier, I can control which controller will present the v-disk but it seems my hpux hosts see disk on port1 or port2 or both.

Thanks.

[Uwe Zessin]

When a virtual disk is mapped into the LUN address space of a host, it appears on all 4 ports. This is necessary so that the multipath software can detect so-called standby-paths.

On the EVA, a virtual disk is managed by one controller at a time. On the 3000+5000 the LUNs on the other controller report a 'not ready' when I/O is tried through the other controller.
That's why PVLINKS does not really work on those models/ is not supported.

On the 4000/6000/8000, the request is redirected to the managing controller (similar to the pre-merger HP VA7000 series storage array).

[Mark Johnson_1]

I believe I have everything sorted out. A modification to my zoning and a timely reboot shows me a consistent result. If I zone both ports to my single path HBA (seperate target-initiator zones) I see my disk(s) down two paths. If I zone one port, I now see only one path to the disk. My results are now consistent and predictable. Thanks for all the advice.