gvinum and raid5

[Peter Giessel]

On Friday, November 02, 2007, at 01:04AM, "Joe Koberg" <joe at rootnode.com> wrote:
>Ulf Lilleengen wrote:
>> On ons, okt 31, 2007 at 12:14:18 -0300, Marco Haddad wrote:
>>   
>>> I found in recent researchs that a lot of people say gvinum should not be
>>> trusted, when it comes to raid5. I began to get worried. Am I alone using
>>>
>>>     
>> I'm working on it, and there are definately people still using it. (I've
>> recieved a number of private mails as well as those seen on this list). IMO,
>> gvinum can be trusted when it comes to raid5. I've not experienced any
>> corruption-bugs or anything like that with it. 
>>   
>
>The source of the mistrust may be the fact that few software-only RAID-5 
>systems can guarantee write consistency across a multi-drive 
>read-update-write cycle in the case of, e.g., power failure.

That may be the true source, but my source of mistrust comes from a few
drive failures and gvinum's inability to rebuild the replaced drive.

Worked fine under vinum in tests, tried the same thing in gvinum (granted,
this was under FreeBSD 5), and the array failed to rebuild.

I can't be 100% sure it wasn't a flakey ATA controller and not gvinum's
fault, and I no longer have access to the box to play with, but when I was
playing with gvinum, replacing a failed drive usually resulted in panics.