What is Secure Path for ?

[benoit Bruckert]

HI,
I'm studying an quotation of a vendor on a new hardware/software solution.
My current config is :
1 HP-UX server, 2 FC Hub (not switch), 2 FC disks trails. disks and hubs are stored in 2 separate rooms, just the server is alone.
I had cross linked disks trails and hubs to manage any failure of disks. (disks are mirrored with Mirror-UX). By this way I have on my system trough LVM a primary and an alternate path to the disks.

I would like to change hubs to FC switch. For this the vendor quote : Securepath HP licence.
Currently I don't have such a software, and I don't need it (primary alternate path is enough for me).
My question is : does I need this product ? as I want to keep the same logical configuration (mirror disks through mirror UX). Does with switch I have still alternate / primary paths ? Is it a specific feature to add if you want to use switches ?

[Jeff Schussele · Accepted solution]

Hi Benoit,

No you don't need SecurePath SW if all you need is alt links. LVM can do that for you.

One thing to be prepared for is that your controller instances *will* change when you introduce the switch. So vgexport -s all the VGs currently on the array & then vgimport -s to get them back. Of course make sure you have good backups - JUST TO BE SAFE.

Rgds,
Jeff

[Stefan Farrelly]

SecurePath load balances across primary and alternate links in LVM, but even better it is transparent for any type of switch or fibre failure. If you setup secure path then pull a fibre from the HP to switch, or switch to disk subsystem, securepath sorts out the alternate path without any errors in dmesg or syslog or the diags. Very nice. Weve just been testing it last week and im impressed. It gives the best throughput and performance across available controllers, and offers transparent fault tolerance.

[Alzhy]

SecurePath is needed only if you have StorageWorks Arrays (ie. EVA, HSG80...). The recent version also supports XP arrays (the rebadged Hitachi Array products) although one can do with Veritas DMP with XP arrays.

SecurePath is needed if you will be using LVM and StorageWorks Arrays (HSG80/EVA) as it offers load balancing and transparent failover as well as on-line LUN addition and replacement. You cannot do without it on HPUX if you want high availability altough single paths are supported.

My advice though would be to use Veritas Volume Manager (full version) if using XP (Hitachi) arrays on HPUX11i -- if path protection and load balancing is desired. For Compaq StorageWorks (EVA, HSG90..) -- always demand SecurePath in the mix -- and specifically use SecurePath 3.0C.

[benoit Bruckert]

thanks all for your replies, and especially Jeff who confirmed my mind. The cost of Secure Path + support is about 10000 $, and I'm very short on my budget, if I can remove this cost, it's better because my config is very simple...

[benoit Bruckert]

Nelson,
I just read again your post and you said that for EVA disks you need this product to get alternate path.
I don't need load balances for my conf, but I need to keep alternate path (which is what i have trough LVM). Does this mean that I will loose this feature by changing disks+hub, and pay a new software to get it back ?

regards

[Alzhy]

I trust that you are using EVA?

For which you can not do away without it even if you are not after load balancing and are only after path protection. You can have the EVA configured for single paths so your LUNS appear on both FC paths but such a config WON'T still support PVLINKS... there is some talk FULL support at the LVM/HPUX level will eventually come with a "future" release of HPUX 11i but until it comes to reality -- you cannot do away without SecurePath -- unless you'd want a config without PATH protection to the LUNs.

[doug mielke]

Also note that most doc. on hp.com claims no support for even single path EVA's with out Secure Path.

It turns out that it is supported, but in that it's documented both ways (older doc says no support) we didn't want to risk non support from Compaq during an emergency.

I'd collect some support doc. before I made a decision to forgo secure path.

[Jeff Schussele]

I don't believe Benoit will *need* SecurePath.
He's just replacing FC hubs with a switch on the way to an FC enclosure.
For that SecurePath is not required.
The switch will just be zoned such that the disks will be presented down 2 paths to his HBAs. Then LVM will just see them as seperate paths to the same LUNs.

Benoit - It might help if you tell us just what switch make/model you're planning to obtain.

Rgds,
Jeff

[benoit Bruckert]

waouh !
My question doesn't seem so stupid in fact !
Hub (short waves) would be replaced by low/end SAN switch (2/8 EL), and the disks : currently 18,2 FC disk in an HA1010 enclosure, would be replaced by EVA3000.
I don't need raid functionnalities for these disks, i just want to keep the same logical conf.