mjhjmtu

Our Management bought a New EMC2 VNX storage device, and a guy from the vendor came to create the LUNS.

I honestly have no idea how to configure the EMC SANS as I never got a chance to work on such awesome things. Now finally I got it.

I know that final step is to mount it as a partition.

But what I need to know is what are the things involved between creating the LUNs and mounting the storage as a partition on the server.

I will mount it on Redhat 5.9 and Redhat 6.4

Usually if you rescan the SCSI bus udev will create the device file for the LUN after which point you treat it like you would any other storage volume (local disk or otherwise). There's a script to do the rescan in the sg3_utils package called rescan-scsi-bus.sh

Rescanning should be sufficient, but in case it's not (usually indicates a driver issue) rebooting will cause the HBA to log back into the SAN and get a new list of LUNs that have been presented to it.

You'll be able to see the LUN when you do an ls -l /dev/disk/by-path For example:

[jadavis6@lrgarfield ~]$ ls -l /dev/disk/by-path
total 0
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:0:0-part2 -> ../../sda2
lrwxrwxrwx 1 root root 10 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:0:0-part3 -> ../../sda3
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:1:0 -> ../../sdb
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:01:00.0-scsi-0:2:2:0 -> ../../sdc
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x500601653ee0025f:0x0000000000000000 -> ../../sdd
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x500601653ee0025f:0x0008000000000000 -> ../../sde
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x500601653ee0025f:0x0009000000000000 -> ../../sdf
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x5006016d3ee0025f:0x0000000000000000 -> ../../sdg
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x5006016d3ee0025f:0x0008000000000000 -> ../../sdh
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x5006016d3ee0025f:0x0009000000000000 -> ../../sdi
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x500601663ee0025f:0x0000000000000000 -> ../../sdj
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x500601663ee0025f:0x0008000000000000 -> ../../sdk
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x500601663ee0025f:0x0009000000000000 -> ../../sdl
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x5006016e3ee0025f:0x0000000000000000 -> ../../sdm
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x5006016e3ee0025f:0x0008000000000000 -> ../../sdn
lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.1-fc-0x5006016e3ee0025f:0x0009000000000000 -> ../../sdo

The Fibre Channel LUN's have the -fc- transport listed. -scsi- devices are internal storage.

Be warned, if the fibre channel card was able to log into the SAN you'll see what's referred to as LUNZ which is apparently one of the ports on the SAN you're connected to. You can tell a path is LUNZ if it's LUN ID (the hex number after the last colon) is all zero's. For example, in the above output this is one of the LUNZ's:

lrwxrwxrwx 1 root root 9 Jan 27 17:17 pci-0000:1a:00.0-fc-0x500601653ee0025f:0x0000000000000000 -> ../../sdd

I've never gotten a full explanation from any SAN guy I've talked to as to why Fibre Channel does that, but just know it's going to be there, it's going to be the first LUN the FC sees (so it gets the lowest number), and you can't treat it like a LUN at all, it's just sort of there. Once you start seeing a LUN with a non-zero LUN ID you'll know that's your target LUN.

EDIT:

I will say this: LUNZ does make it easier to see if the HBA is able to log into the SAN (although you could still see such by way of FLOGI errors in /var/log/messages). If you install a new HBA and DON'T see a LUNZ off it, that's usually an indication that the firmware on the device or the driver for it needs to be updated.

EDIT #2:

These are the steps strictly required, if you're doing pathing, you'll probably want to install PowerPath or configure multipathd. But that's a whole task unto itself. It's better to just mention that, let you do your research and come back with any specific questions.