Installing EMC PowerPath Keys

 

This describes how to configure the EMC PowerPath registration keys.

First, check the current configuration of PowerPath:

# powermt config
Warning: all licenses for storage systems support are missing or expired.

The install the keys:

# emcpreg -install
=========== EMC PowerPath Registration ===========
Do you have a new registration key or keys to enter?[n] y
Enter the registration keys(s) for your product(s),
one per line, pressing Enter after each key.
After typing all keys, press Enter again.
Key (Enter if done): P6BV-4KDB-QET6-RF9A-QV9D-MN3V
1 key(s) successfully added.
Key successfully installed.
Key (Enter if done):
1 key(s) successfully registered.

Note: the license key used in this example is not valid

Remove LUNS From Linux Safely

This post uses the QLogic Dynamic Target and LUN Discovery utilities. The steps below apply to SLES 10 and RHEL 5 servers using QLogic HBAs and PowerPath. This post also assumes that you have put the qlogic utilities into /tmp/ql_utils.

To remove a LUN and all associated PowerPath and Linux devices from the host environment follow these steps. 

Note: that it is critical to follow the procedures in exact order because deviating from the procedures can cause the host to panic

These steps were put together using steps from QLogic KB articles.

Scan and Configure New SAN disks on Linux

The steps below are to scan for new LUNs from SAN after the LUNs have been presented from the storage side. And the steps below is when you are using QLogic HBA's . 


This post uses the QLogic Dynamic Target and LUN Discovery utilities which can be downloaded from:

http://driverdownloads.qlogic.com/QLogicDriverDownloads_UI/SearchByProduct.aspx?ProductCategory=39&Product=935&Os=126

The steps below will work on SUSE Linux Enterprise Server (SLES) 10 and Red Hat Enterprise Linux (RHEL) 5.

Create a directory to hold the utilites. In this examle we will use the /tmp/ql_utils directory:

mkdir /tmp/ql_utils

Linux SAN Multi path for HP EVA Storage

Instead of installing the original device-mapper-multipath package there is a simillar package from HP called HPDMmultipath-[version].tar.gz that has already a configuration for HP EVA and XP storage devices. The HPDMmultipath-[version].tar.gz can be downloaded from www.hp.com

# tar -zxvf HPDMmultipath-3.0.0.tar.gz
 # cd HPDMmultipath-3.0.0/RPMS
 # rpm -ivh HPDMmultipath-tools[version]-[Linux-Version]-[ARCH].rpm

 # vim /etc/multipath.conf

defaults {
        udev_dir                /dev
        polling_interval        10
        selector                "round-robin 0"
        path_grouping_policy    failover
        getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
        prio_callout            "/bin/true"
        path_checker            tur
        rr_min_io               100
        rr_weight               uniform
        failback                immediate
        no_path_retry           12
        user_friendly_names     yes
}

Linux SAN Multipathing using device mapper

There are a lot of SAN multipathing solutions on Linux at the moment. Two of them are discussesed in this blog. The first one is device mapper multipathing that is a failover and load balancing solution with a lot of configuration options. The second one (mdadm multipathing) is just a failover solution with manuel re-anable of a failed path. The advantage of mdadm multiphating is that it is very easy to configure.

Before using a multipathing solution for a production environment on Linux it is also important to determine if the used solution is supportet with the used Hardware. For example HP doesn’t support the Device Mapper Multipathing solution on their servers yet.

Device Mapper Multipathing

Procedure for configuring the system with DM-Multipath:

1. Install device-mapper-multipath rpm
2. Edit the multipath.conf configuration file:
   • comment out the default blacklist
   • change any of the existing defaults as needed
3. Start the multipath daemons
4. Create the multipath device with the multipath