pv-links

[Grayh]

What are PV Links

Is pvlinks suppiorted on EVA 4100 and if so how can this be implemented on this.

OS: HP-UX 11i V3

Is there an alternative

[Torsten.]

You can do it, but with 11.31 pvlinks are no longer needed.

Just use the new device file, e.g.

/dev/disk/disk7

this covers all available links.

Check with

ioscan -m dsf

[Grayh]

Can you provide me some more info on this... I couldn't understand you...

why are pvlinks used and is there an alternative for this...

[Torsten. · Accepted solution]

On systems up to 11.23 pvlinks are the alternative pathes to a storage device.

You will see them in vgdisplay:

...
--- Physical volumes ---
PV Name /dev/dsk/c6t0d1
PV Name /dev/dsk/c14t0d1 Alternate Link
PV Name /dev/dsk/c8t0d1 Alternate Link
PV Name /dev/dsk/c16t0d1 Alternate Link
PV Status available


With 11.31 it is different:

--- Physical volumes ---
PV Name /dev/disk/disk19
PV Status available
Total PE 159
Free PE 15
Autoswitch On


# ioscan -m dsf
Persistent DSF Legacy DSF(s)
========================================
/dev/rdisk/disk19 /dev/rdsk/c1t0d1
/dev/rdsk/c2t0d1


The "disk19" device will cover both pathes and it will even manage the "adjustable" load balancing.

[Torsten.]

On systems up to 11.23 pvlinks are the alternative pathes to a storage device.

You will see them in vgdisplay:

...
--- Physical volumes ---
PV Name /dev/dsk/c6t0d1
PV Name /dev/dsk/c14t0d1 Alternate Link
PV Name /dev/dsk/c8t0d1 Alternate Link
PV Name /dev/dsk/c16t0d1 Alternate Link
PV Status available


With 11.31 it is different:

--- Physical volumes ---
PV Name /dev/disk/disk19
PV Status available
Total PE 159
Free PE 15
Autoswitch On


# ioscan -m dsf
Persistent DSF Legacy DSF(s)
========================================
/dev/rdisk/disk19 /dev/rdsk/c1t0d1
/dev/rdsk/c2t0d1


The "disk19" device will cover both pathes and it will even manage the "adjustable" load balancing.

[Fabio Ettore]

Hi,

generally talking PV links are links t oaccess to physical volumes. Usually the concept of PV links is useful when working on multiple paths to a PV, esepcially when balancing load (but balancing asks for an additional SW). Or the concept can be applied when having just redundant paths to access to a PV (if one link goes down you have other PV link to access to PV).

However, as already posted, in HP-UX 11.31 there is a new I/O addressing concept with multipath SW already built in when using I/O address like /dev/disk/diskX. So you don't need anything else, you should just use that device file when configuring a volume group. Said that you could also want to use other multipath SW.

HTH.

Best regards,
Fabio

[Robert-Jan Goossens_1]

Hi,

Have a look at this link.

http://h18006.www1.hp.com/products/sanworks/secure-path/

Regards,
Robert-Jan

[Torsten.]

R-J: secure path and 11.31 doesn't fit together very well ...

[TTr]

> What are PV Links
PV-links is a built-in feature of LVM that handles multiple device paths to the same disk.
> Is there an alternative
In 11.31, yes. Both LVM (pv-links) and DSF are available. With large disk arrays, each disk has two paths that lead to it which translate to two separate device files for the same disk. With pv-links you have to use both device files in LVM and use one of them as the primary and the other as the alternate paths. With DSF, both device paths for the same disk are replaced by a virtual disk device such as /dev/disk/disk7 that Torsten mentioned. You only use this single device in you LVM configuration and the DSF structure automatically translates this single virtual device to one of the physical paths to your disk. If one path fails, the other one is used automatically.

[Robert-Jan Goossens_1]

Thorsten.

--
HP now supports the native failover capabilities that are included with operating systems for Windows (MPIO), Linux (Device Mapper), HP-UX (11i v3), Sun/Solaris (MPxIO), IBM/AIX (MPIO) and Netware (MPIO).

While HP continues to offer and support the Secure Path products, we are encouraging customers to transition to these native solutions. For more information about these native solutions, please contact your local sales representative.
--

I did not suggest to use secure path :-)

Best regards,
Robert-Jan

[Torsten.]

I read this too, but IMHO posting the link about secure path only is a bit confusing ... much better now ;-)

[Grayh]

Thank you torsten

[Torsten.]

It would be fair to assign points to **all** who was trying to help you - this is the way to make new friends ...

Have fun!