[Bioclusters] Urgent advice on RAID design requested

Paul Rafferty paulrafferty at mindspring.com
Tue Jan 16 22:26:20 EST 2007

You didn't mention if outside of reliability issues, your FS4500  
currently meets your performance requirements.  If it does, or is  
adequate, make sure you buy as many physical disks for your new  
storage array as you have now.  There is no substitute for spindles.

Drives fail most often on initial startup and during any rebuild -  
especially SATA drives.  With SATA arrays I use only RAID 10 or  
RAID6.  Unfortunately this tends to depress their cost per TB  
advantage over SCSI and FC.   Enterprise SATA drives really don't  
exist other than in a marketing glossy.

With respect to reliability - based on the HP quote containing one 8  
port switch, I assume your hosts only have a single HBA in them?  Did  
HP quote the MSA with the redundant controller option?   I have some  
MSA storage in my environment and have no complaints.  However, we  
have it all pretty well built out (lots and lots of 15k rpm drives)  
with RAID 10.

Also, have you considered iSCSI options rather than FC based arrays?   
This might help you put money into controllers/drives rather than  
SFPs and fibre switches - assuming your network can handle jumbo frames.

On Jan 15, 2007, at 11:17 AM, martin goodson wrote:

> I'd like to ask for some advice on the design of a new storage system:
> We are looking to buy a basic SAN storage system with ~ 4 TB usable
> capacity. Our total budget is £15,000 (~$25,000?). The filesystem  
> is for
> bioinformatics computational work including a fair amount of  
> database access
> but also typical bioinformatics flat file access (>1Gb files).
> We would like good performance but really reliability is the number  
> one
> issue. The SAN would be in use day and night by a 60 node cluster  
> so I guess
> we would be looking at enterprise level reliability if not 24/7 (is  
> there a
> difference?). We plan to attach 4 servers to the SAN which all  
> would be
> linux intel/AMD.
> We have been using RAID5 SATA with an adaptec fs4500 box with  
> really bad
> experiences so we would really like to get this right. (We have had  
> problems
> with the controller as well drives failing during RAID5 rebuild.) Good
> hardware monitoring would be a must. The controller and basically  
> the whole
> system must be really well supported, especially in Linux. Our  
> sysadmin is
> really overloaded and would prefer something that does not suck up  
> all her
> time in maintenance and configuration.
> Just to be perfectly clear, our priorities are reliability >>> size >
> performance.
> We already have a quote from HP for a SCSI Modular Storage Array  
> with SAN
> Switch 2Gbit/8 port BASE SAN KIT.
> Is this a reasonable setup. Does anyone have any experience with  
> this kit or
> can suggest alternatives?
> Is SCSI over-specifying? Are enterprise SATA drives / controllers / 
> systems
> now up to scratch? Should we be using RAID6 or RAID10?
> We would really really appreciate some help here.
> Thanks in advance,
> Martin Goodson
> Functional Genetics Unit
> Oxford University
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