Storage query on HP-UX

[Rajesh Karelia]

Hi,

In our test environment, we have two rx2620 HP-UX nodes in a cluster configuration with EVA4000 SAN as storage.

The following LUNs on EVA are visible to only UDSTST1:
HPUX_UDS1_Sys_Disk_1 (30GB)
HPUX_UDS1_Sys_Disk_2 (30GB)
HPUX_UDS1_App_Disk_1 (30GB)
HPUX_UDS1_App_Disk_2 (30GB)

The following LUNs on EVA are visible to only UDSTST2:
HPUX_UDS2_Sys_Disk_1 (30GB)
HPUX_UDS2_Sys_Disk_2 (30GB)
HPUX_UDS2_App_Disk_1 (30GB)
HPUX_UDS2_App_Disk_2 (30GB)

The following LUNs are visible to both nodes for MC Service Guard Application running Oracle 10g:
HPUX_Lock_Disk_1 (1GB)
HPUX_Lock_Disk_2 (1GB)
HPUX_DB_File_Disk_1 (500GB)
HPUX_DB_File_Disk_2 (500GB)
HPUX_DB_Bck_Disk_1 (250GB)
HPUX_DB_Bck_Disk_2 (250GB)

All LUNs ending with _2 are the mirror sets of LUNs ending with _1.

When I created indivual LUNs on EVA, each one is visible as 4 different disk device on a node.
eg, when I created HPUX_UDS1_Sys_Disk_1 on EVA and presented it to UDSTST1 node, it was visible as:
> disk 4 0/3/1/0/4/0.20.1.0.0.0.1 sdisk CLAIMED DEVICE HP HSV200
> /dev/dsk/c4t0d1 /dev/rdsk/c4t0d1
> disk 3 0/3/1/0/4/0.20.5.0.0.0.1 sdisk CLAIMED DEVICE HP HSV200
> /dev/dsk/c6t0d1 /dev/rdsk/c6t0d1
> disk 84 0/4/1/0/4/0.10.1.0.0.0.1 sdisk CLAIMED DEVICE HP HSV200
> /dev/dsk/c8t0d1 /dev/rdsk/c8t0d1
> disk 83 0/4/1/0/4/0.10.5.0.0.0.1 sdisk CLAIMED DEVICE HP HSV200
> /dev/dsk/c10t0d1 /dev/rdsk/c10t0d1

Why is it like this?
If I want to load HP-UX on this system disk, which path should I select.
If I want to create a Logical Volume of Application disks, which device name should we use?
If I want to create a VxVM disk group of Oracle DB file and Backup file disks, then which device name should we use?

Please suggest.

Thanks,
Rajesh

[Arunkumar.B]

Hi Rajesh,


Its because ur controller having 4 path.You can use any one of the device file of 4.


Cheers
Arunkumar.B

[Ninad_1 · Accepted solution]

Hi Rajesh,

You can see 4 disk device names corresponding to 4 paths you have from your server to the LUN - via multiple HBA ports/SAN switches.
This is useful to have redundancy against failure of say a HBA port or a SAN switch port/SAN swicth - so that the LUN is still visible to you via alternate path.
When using in LVM/VxVM you can use these different paths as alternate paths.
While creating a Volume group if you mention the other device names for the disks , LVM understands that and configures one as primary path (the disk name which you have given first) and remaining as Alternate Link .
In VxVM the vxdmpadm can use these as alternate paths.

Hope this clarifies,
Ninad

[Enrico P.]

Hi,
lun view depens from your SAN (Storage Area Network) configuration (number of connection from Storage/Server to the switchs and number of switch) ,
so if you have:

-two FC connection from the Storage to the same switch
-two FC connection from the server to the same switch

you will the same lun from four path because you have four channel to see the lun from the server.

You can use the lun how you planned, remember to add the PV link in the vg when you create it.

Es. vgcreate vgname /dev/dsk/c4txdx /dev/dsk/c6txdx /dev/dsk/c8txdx /dev/dsk/c10txdx

Enrico

[spex]

Rajesh,

We have a similar configuration on one of our servers, with each of our AutoRAID 12H LUNs showing up four times. Each AutoRAID has two disk controllers, and each controller is connected to our MUX on two channels. There's nothing wrong with this configuration. When creating your volume groups, state the device you want to be your primary path first, followed by alternate link devices.

PCS

[Rajesh Karelia]

Thanks very much everyone.
It was very useful.

Rajesh