Disk Problem

[Alan Sawyer_2]

Hi, I've recentley re-built a SAN with new disks and moved the enclosure. Now when I create a unit on the HSG80 in Multibus_failover mode the drive is displayed twice in Disk manager, I've upgraded all the patches etc and changed SCSI Version to 2/3 I've now changed it back to 3 as 2 didn't make any difference. I've now shutdown the other controller and it only reports 1 drive - any ideas as I would like both controllers up.

[Uwe Zessin · Accepted solution]

Apparently you are missing a multipath filter driver for your operating system (Windows?). It has nothing to do with the SCSI_VERSION setting on your HSG.

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

[Mohammad_14]

Dear;

If you are using Windows invironment you must install Auto Path software for (win2000) or secure path (for win2003) that will solve problem, in UNIX environment all Unix Platforms will see two special names for singile unit thats normal.

[Uwe Zessin]

AutoPath is for HP's pre-merger VA and XP series storage arrays - the HSG requires Secure Path. Watch out: AutoPath has now been bundled into Secure path, but you need the true SP driver.

> in UNIX environment all Unix Platforms will see two special names for
> singile unit thats normal.

That isn't correct either, I am afraid. Tru64 Unix, for example, has an embedded multipath feature and all redundant paths are hidden.

[SAKET_5]

Alan,

agreed with Uwe's response.

Mohammad, the paths that you see to a Logical Storage Unit are calculated based on the end-point mappings between the HBA port & and the target host ports on the controllers' backend - depending on the fabric setup whether you have redundant, dual fabric with dual HBA ports in your server, you will see 4 paths assuming you are using a controller with 2 host ports in one fabric and 2 in the other. If you look at the many possible paths within your fabric topology you most likely have more than 4 paths to reach to the storage unit from a particular HBA port, these redudant paths are taken care by FSPF protocol which makes shortest paths routing decision and figures out the cost metrics for paths. My point being, it is the number of end-point mappings which reflects as the number of paths to your disk that you see at the OS end.

All OSs need a flavour of multi-pathing daemon working in kernel space to cope with the multiple paths that the OS would otherwise see to the same disk device - choice of OS may warrant varying software (whether inbuilt or an add-on piece of software) which allows you to (Tru64 - OS comes with multi-pathing daemon capable of doing failover of LUNs only, Solaris - you can use MPxIO (Free) to achive the same, Windows - you can use MPIO (Free) with EVAs or paid for Secure Path software)to achieve your goal.

Autopath...when you install Secure Path on Windows, you would see a pop-up question to pick whether you want to install VA support (autopath driver) or you just want Secure Path driver. Do not mix them up.

Hope, it helps.

Regards,
Saket.