[Beowulf] Big storage

[Bruce Allen]

Hi Gerry,

So far the only problem we have had is with one Areca card that had a bad 
2GB memory module.  This generated lots of (correctable) single bit errors 
but eventually caused real problems.  Could you say something about the 
reliability issues you have seen?

Cheers,
 	Bruce


On Wed, 16 Apr 2008, Gerry Creager wrote:

> We've used AoE (CoRAID hardware) with pretty good success (modulo one RAID 
> shelf fire that was caused by a manufacturing defect and dealt with promptly 
> by CoRAID).  We've had some reliability issues with Areca cards but no data 
> corruption on the systems we've built that way.
>
> gerry
>
> Bruce Allen wrote:
>> Hi Xavier,
>> 
>>>>>> PPS: We've also been doing some experiments with putting 
>>>>>> OpenSolaris+ZFS on some of our generic (Supermicro + Areca) 16-disk 
>>>>>> RAID systems, which were originally intended to run Linux.
>>
>>>>>  I think that DESY proved some data corruption with such configuration, 
>>>>> so they switched to OpenSolaris+ZFS.
>> 
>>>> I'm confused.  I am also talking about OpenSolaris+ZFS.  What did DESY 
>>>> try, and what did they switch to?
>> 
>>> Sorry, I am indeed not clear. As far as I know, DESY found data corruption 
>>> using Linux and Areca cards. They moved from linux to OpenSolaris and ZFS, 
>>> avoiding other corruption. This has been discussed in HEPiX storage 
>>> workgroup. However, I can not speak on their behalf at all. I'll try to 
>>> get you in touch with someone more aware of this issue, as my statements 
>>> lack of figures.
>> 
>> I think that would be very interesting to the entire Beowulf mailing list, 
>> so please suggest that they respond to the entire group, not just to me 
>> personally.  Here is an LKML thread about silent data corruption:
>> http://kerneltrap.org/mailarchive/linux-kernel/2007/9/10/191697
>> 
>> So far we have not seen any signs of data corruption on Linux+Areca systems 
>> (and our data files carry both internal and external checksums, so we would 
>> be sensitive to this).
>> 
>> Cheers,
>>     Bruce
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>
>