Secure Path/EVA3000/VCS3.0.28/HP-UX11iV1

[Andrew Moody_1]

Please feel free to pretend I'm an idiot.

spmgr DISPLAY gives the following output

Command: spmgr display
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
Storage: 5000-1FE1-5004-3010
Load Balance: Off Auto-restore: Off
Path Verify: On Verify Interval: 15
HBAs:td0 td1
Controller: P66C5E2AAQV071, Operational
P66C5E2AAQV06H, Operational
Devices: c38t0d0

TGT/LUN Device WWLUN_ID H/W_Path #_Paths
0/ 0 c38t0d0 6005-08B4-0010-271A-0000-7000-01EE-0000 4
255/255/1/0.0
Controller Path_Instance HBA Preferred? Path_Status
P66C5E2AAQV071 no
c33t0d1 td0 no Active
c30t0d1 td1 no Available

Controller Path_Instance HBA Preferred? Path_Status
P66C5E2AAQV06H no
c36t0d1 td0 no Standby
c32t0d1 td1 no Standby


As I understand it the Standby paths are as a result of that controller being passive. However for the active controller my two paths are active and available. Can I make both these paths active and if so how? Sever is HP-UX 11iV1

Thanks

[Luk Vandenbussche]

Andrew,

This is a perfectly fine secure path output for VCS 3.028 on HPUX.

There is always one connection active and the other is available on the active controller.

You can change the option with spmgr set.

[Andrew Moody_1]

Cheers Luk

Would using spmgr set change both path_status to active on the Active controller?

Can I use the -b option on spmgr set to load balance? If so how?

[Andrew Moody_1]

Ok I think I've worked out how to turn load balancing on. Which algorithm for performance?

Round Robin? Least i/o? which anyone know?

[Pat Obrien_1]

round robin saves me 20 minutes on a 8 hour batch job over least service time.

[Ian Vaughan]

Howdy,
Just my 2p's worth -

Shortest queue (least i/o) needs to take a look at the queue -> faster than no load balance.

Round Robin - Simple & fast -> faster than Shortest Queue.

2 vdisks - one preferred path A, other preferred path B - LVM striped 256KB -> faster than a very fast thing indeed.

Also while testing found that PCI-X HBA on a combo card (with a 1000base-t can't remeber p/n) was faster than a dedicated PCI-X? Dunno if it was different chipset or driver that makes the difference.

Hope this is of some help.
Ian

[Andrew Moody_1]

On Ian's suggestion above. Striping the LV over 2 vdisks with alternate preferred paths, am I right in thinking that would only bring performance benefits in an EVA where both controllers were in play ie active-active?

With our active-passive setup (VCS 3.28/EVA3000) the controller is passive for the Array not the LUN yes? In that scenario would striping give a performance benefit?

We've been advised by local HP engineers to hold off on VCS 4* (and therefore active-active on EVA3000) for the time being.

Andrew

[Ian Vaughan]

Howdy,
By pegging one vdisk to preferred path A and the other to preferred path B you are using 2 vdisks and 2 "Active" controllers.

The active/active vs active/passive thing is the fact that on EVA 4/6/8k & 3&5k with VCS 4.x the *vdisk* can be "seen" all the time on both controllers (4 or 8(on 8000) representations of the same vdisk).

With Active/passive the disk is only seen on the controller which is active and SecurePath sits in the way to manage failover & load balancing and make sure that the OS doesn't care. The load balancing is on the 2 paths that get you to the active controller.

HTH
Ian

[Ian Vaughan]

As Columbo used to say:
Just one more thing...
After a brief conversation with 2 of my colleagues -
Ultimate performance layout is 4 equal sized vdisk all in 1 disk group.
Secure Path - load balance off, failover failback - on.
Set preferred paths one to each controller port and put your seatbelt on.

This can be approximated to with VCS 4.x by careful ordering of the PV's in your VG.

HTH
Ian

PS -
Shameless Plug: My company name is in my profile and this is what we do day in day out. Get in touch if you need to.

[Uwe Zessin]

> With Active/passive the disk is only seen on the controller which is active

On the EVA, both controllers are 'active', but a single virtual disk is only managed by one at a time.
A virtual disk is 'seen' on all controller ports, but you can't do I/O through the controller that does not 'own' the virtual disk - those are the 'Standby' paths. If the standby paths were not seen, the failover software would not be know where to switch to in case the Active/Available paths go down.