High Availability NFS server configuration....

Mansell, Gary GRMansell at ricardo.com
Thu Mar 6 11:18:19 CST 2003


Dear all,

I have a Dell PE2650 with two internal Qlogic qla2300 HBA's that attach via two seperate fibre cables directly into an EMC FC4500 disk storage array configured with 1TB of RAID 5 storage. The machine is an NFS /SMB server to the whole company. The storage array has two SP controlers installed, currently I am only using one of the HBA's to communicate to one of the FC4500 SP's. The other controller and SP is there so that I can manually reconfigure it into action should the other channel fail. Obviously this will involve downtime to reconfigure the system.

I would like to make this solution more slick so that it does not require any / as much operator error in time of failure. I was originally intending to purchase the Linux Powerpath software just released by EMC to Load balance the data to and from the FC4500 across the two HBA cards and also to provide a dynamic failover capability should one of the HBA's or fibre cables fail. I have heard that this may not work with my FC4500 because it is not intelligent like the FC4700? 

Another solution that has been suggested to me is to use Linux's LVM and it's md multipathing capability that comes with the O/S coupled with the Qlogic v6.04 (failover capable) driver for my FCAL cards. This should (for no extra cost :-) ) give me the resilience that I desire.

Does anyone have any experience of the above configuration? 

Is there something that I am overlooking?

Where can I find out more about LVM and multipathing, I have tried googling for it but have not found any Howto's etc? 

Will both multipath channels to the disk be "live" at the same time so that I can load balance or will the second only kick in when the primary channel fails.

How robust is this solution (is it bleeding edge or well tested) - my server is critical to the company?

Thanks in advance for any light that you may be able to shed on this matter....

Gary Mansell
Senior Technical Analyst
IT Department
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