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Multipathing with NetApps

 
Brendan Newport_2
Frequent Advisor

Multipathing with NetApps

Hi!

I have an 11.16 RAC/ServiceGuard cluster, using NetApp 3020 filers, with RX4640's and a quorum server running Hp_UX 11.23. We employ LVM rather than vxvm.

We use PVLinks for multi-pathing support, but it is somewhat limited, inasmuch as all we really get is lots of alternate paths to storage, with just one primary path. Below is an example;

--- Physical volumes ---
PV Name /dev/dsk/c12t0d1
PV Name /dev/dsk/c13t0d1 Alternate Link
PV Name /dev/dsk/c20t0d1 Alternate Link
PV Name /dev/dsk/c17t0d1 Alternate Link
PV Name /dev/dsk/c15t0d1 Alternate Link
PV Name /dev/dsk/c18t0d1 Alternate Link
PV Name /dev/dsk/c19t0d1 Alternate Link
PV Name /dev/dsk/c14t0d1 Alternate Link
PV Status available

So we get 8 paths to each LUN presented, but with PVLinks, just one path is active at any one time - with 7 x redundant paths to storage.

A RedHat platform we employ is also attached to the NetApps filers. Here, all 8 paths are employed, enabling perfomance over 2 FC HBA's and four-paths-per-adapter to/from the storage.

My question is, is there a way of getting equivalent capability? Perhaps by employing vxvm and its DMP? Anyone know if NetApps client driver will provide true multi-pathing through DMP?

Thanks


Brendan
4 REPLIES 4
Ninad_1
Honored Contributor

Re: Multipathing with NetApps

Hi,

HP Secure path software can be useful in that case
I believe in HPUX 11.31 - load balancing in inherent with the OS LVM.

Regards,
Ninad
Brendan Newport_2
Frequent Advisor

Re: Multipathing with NetApps

Hi Ninad!

Thanks for the answer.

have you actually seen or have Securepath working with netApps filers?

This old posting from 2004 suggested that Securepath was only for EVA's/VA/VP etc.

http://forums11.itrc.hp.com/service/forums/questionanswer.do?threadId=711283
Ninad_1
Honored Contributor

Re: Multipathing with NetApps

Hi,

No. I do not have securepath.
You are right secure path is supported for HP Storage arrays.

What best you can do in this situation is distribute the paths for different PVs so that say one PV uses path A as primary and paths B, C, D ... as Alternate links, then for other PV have Path B as primary and C, D, ...A as alternate links and so on.

Regards,
Ninad
Armin Kunaschik
Esteemed Contributor

Re: Multipathing with NetApps

SecurePath does not work with Netapp LUN's.

What you're trying to do is probably not good/supported. Netapp LUN's are active/passive by default. You can use all links alltogether because you'll use the interlink between the filers and this could affect the netapp cluster function. This is not supported by Netapp and the Netapp box will complain about the secondary link usage.
You should only use primary ports for multipathing!

You should get the Netapp Santoolkit from http://now.netapp.com. In the depot you'll find 2 tools ntap_config_paths (for PV Link vg's) and enable_ontap_pvlinks (for agile disks, HP-UX 11.31). See man pages for detail!

Check the primary/secondary ports with (this is 11.31):
# sanlun lun show -p
Results look like:
filer1:/vol/vgdata/lun (LUN 13)
Agile Filename: /dev/rdisk/disk81 VG: /dev/vgdata
512.0g (549782028288) lun state: GOOD
Filer_CF_State: Cluster Enabled Filer Partner: filer1
Multipath_Policy: None
Multipath-provider: HP PV Links
-------- --------- -------------------- ---- ------- ------- -------------
host filer /dev/dsk Primary partner PVlinks
path path filename host filer filer path failover
state type or Hardware Path HBA port port priority
-------- --------- -------------------- ---- ------- ------- -------------
up primary /dev/dsk/c45t1d5 fcd3 6a 0
up primary /dev/dsk/c51t1d5 fcd2 5a 0
up secondary /dev/dsk/c43t1d5 fcd3 5a 1
up secondary /dev/dsk/c37t1d5 fcd2 6a 1

See: Only primary links are supported for multipathing.
There is no native multipathing for 11.23. You can use DMP but you need to care about not using the secondary links. This is probably a pain to configure. My advice: Install 11.31.

My 2 cents,
Armin

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