topic Re: Discover new SAN devices on DMM in Operating System - Linux

Discover new SAN devices on DMM

MSwift — Tue, 01 Feb 2011 19:35:24 GMT

on RHEL 5 when a new SAN disk is added how would i discover it?

Thanks

Mike.

Re: Discover new SAN devices on DMM

Matti_Kurkela — Tue, 01 Feb 2011 20:37:31 GMT

RedHat has written an "Online Storage Reconfiguration Guide" for exactly this purpose:

http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Online_Storage_Reconfiguration_Guide/index.html

Please see Chapter 9: Scanning Storage Interconnects.

MK

Re: Discover new SAN devices on DMM

Alzhy — Tue, 01 Feb 2011 20:49:29 GMT

Generally after presenting disks to a SAN connected LINUX Server - you do the following:

SCAN:
for hba in `ls -d /sys/class/fc_host/host*`;do
FCHOST=`basename $hba`

echo "Scanning $FCHOST"
echo "- - -" > /sys/class/scsi_host/${FCHOST}/scan
done

Then:

multipath -ll

If you need to give your Disks friednlier names like /dev/mapper/EVA08_DB_dsk001 - then add/edit www alias entries in /etc/multipath.conf and do "multipath -v2". Finish off with "multipath -ll" and check if mapper /path entries are present in /dev/mapper and /dev/mpath.

Finish off with using the disk -- paritioning it wholly or whatever are your standards...

The abobve assumes you do not have the Array's proprietary MultiPathing solution engaged -- like PowerPath from EMC or HDLM from Hitachi, etc...

HTH.

Re: Discover new SAN devices on DMM

MSwift — Tue, 01 Feb 2011 23:12:22 GMT

I tried this. The issue_lip command logs into /var/log/messages but the

echo "- - -" > /sys/class/scsi_host/

command does not log anything to the messages. I am not saying that it is not scanning, but it does not log anything.

Just an observation.

Thanks

Mike.

Re: Discover new SAN devices on DMM

MSwift — Tue, 01 Feb 2011 23:16:04 GMT

Again these are qlogic fc's. would that make a difference??

Mike

Re: Discover new SAN devices on DMM

Alzhy — Wed, 02 Feb 2011 14:54:51 GMT

Nope.. it works for both Emulex and Qlogic HBAs (likely Brocade's too)...

We use to use Qloic and Emulex native sacndisks tools but opted for just the simple...

The disks newly discovered are actually logged... if you do a "dmesg" afterwards -- you will see the discoveries made.

If you are using HP StorageWorks Arrays -- EVA, P or XP series, etc... -- please be aware taht it is advisable that you install the HP Device Multipather kit as it gives you the correct /etc/multipath.conf