Linux & Dell/EMC SAN

chris dagdigian dag at
Thu Aug 15 08:42:00 CDT 2002

I have similar issues when I build linux clusters and compute farms for 
bioinformatics and computational biology applications.  In the life 
sciences there is a huge problem -- terabyte volumes of ascii and binary 
data and a huge need for shared concurrent read/write access to these 

SANs are horrible for this type of use case for many reasons including 
the expensive per-port cost of FC switches and the general nastiness of 
trying to share a single volume in a SAN between multiple heterogenous 
systems. Often times you need expensive consulting and layered software 
products to even get close to the promise of shared access. The only 
other option is to burn lots of disk space making multiple copies of all 
your data so each system can have its own dedicated volume.  The 
commercial SAN-NAS heads often times don't do much better than a DIY 
unix box connected to the SAN and serving up NFS to the network.

Because of this I haven't really bothered with SANs for almost 2 years 
now. I've had far better success using high end NAS products from 
companies like Network Appliance to get me what I need: shared access to 
the same files from all sorts of machines (clusters, high end Unix boxes 
& desktops).  NFSv3 has its problems but its far more straightforward, 
trunkable GigE networking gear is dirt cheap and it is pretty easy to do 
clever things with local disk caching and clever network designs to 
engineer around any I/O bottlenecks that appear.  

IBM is pushing GFS but tells you right away that for the best 
performance you need to use fibre channel as the transport. When you add 
up the cost of all the FC HBAs and switches the price starts to get 
really unreasonable. One of my partners is playing pretty seriously with 
the Coda filesystem but he's not convinced yet.

Just to keep this note on topic I'd like to express how sad I am that 
Dell has partnered with EMC for the top end of their storage line. In 
particular the IP4700 NAS product is a steaming pile of garbage -- I've 
met many unhappy IP4700 owners in the last year and a half and absoutly 
zero happy owners which says much. I'm not a NetApp zealot by any means 
but for the price that the IP4700 goes for there are far better NAS 
products available on the market. Dell does its customers a disservice 
by offering the IP4700 as 'high end NAS'.

Like Jason I'd be very interested in hearing about any successful (and 
reasonably priced) linux shared filesystem projects running on top of SANs.

Just my $.02


jason andrade wrote:

>On 14 Aug 2002, Jeff Wolfe wrote:
>>On Wed, 14 Aug 2002 Gary_Lerhaupt at wrote:
>>>EMC has announced Red Hat 7.3 and Red Hat Advanced Server 2.1 qualification
>>>on their CLARiiON line.
>>Is anyone using a shared filesystem on top of their Linux SAN rigs?
>>Reliability? Cost?
>does _anyone_ have a linux SAN rig ?  i went down this track almost 2 years ago
>and at the time the only player in the market was GFS/Sistina.
>i have not heard of anything further down the track so i'd love to know if people
>are doing this yet.  i have > 1TB now in a direct attach fcal deployment which
>i'd like to scale up an order of magnitude..

Chris Dagdigian, <dag at> - Independent Bio-IT & Informatics consulting
Office: 617-666-6454, Mobile: 617-877-5498, Fax: 425-699-0193
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