[Pvfs2-users] Question about redundancy

[Erich Weiler]

IBM's GPFS has done this quite nicely with primary and redundant server 
disks, also they use a concept called 'failover' groups that provide 
backups for nodes with common failure points.  It's a sort of 
replication technique, not exactly a RAID 5 type of redundancy but it 
works.  I understand this kind of thing is not trivial to code; but 
conceptually it seems doable.

-erich

Rob Ross wrote:
> Hi Steve,
> 
> We get this question a lot.
> 
> Software redundancy in a parallel file system is a very challenging 
> problem, particularly to provide efficient access at the same time.
> 
> The group at Clemson has been looking into this as a research project, 
> and I believe that others have as well. If a group creates a solution 
> that performs well, reliably operates, and fits into the rest of the 
> PVFS system, then we would certainly consider integrating it into the 
> production releases. This hasn't happened so far...
> 
> Regards,
> 
> Rob
> 
> Steve wrote:
>> Is built in redundancy planned ? Or not in the scope of the project ?
>>
>> Steve
>>
>> Trusting my 1.1Tb to the reliability of my drives, and touch wood in 20
>> years of computing had never had a drive fail. Now ive just put a 
>> curse on
>> them!
>>  
>> -------Original Message-------  
>> From: Robert Latham Date: 24/04/2007 14:14:13 To: Erich Weiler Cc: 
>> pvfs2-users at beowulf-underground.org Subject: Re: [Pvfs2-users] 
>> Question about redundancy  
>> On Mon, Apr 23, 2007 at 05:03:39PM -0700, Erich Weiler wrote:
>>> I need to be clear on this before putting a lot of time into it, but 
>>> it sounds like this might be a good solution for our firm, as we have 
>>> a 200 node cluster each with one 500GB disk, 400GB of which can be 
>>> leveraged to a massive parallel file system (400GB x 200 nodes = one 
>>> big ~80TB distributed file system). But that assumes that there is no 
>>> redundancy, other wise that 80TB would be more like 50-60TB max or 
>>> something because there would be some redundancy in there... ? 
>>  
>> Murali's explanation is spot-on: no software-based reduncancy scheme.  
>> For users concerned with redundancy, we suggest hardware failover to 
>> Shared storage, which works quite well.  
>> ==rob