If you can ensure that there will be no failures (in which case, you wouldn't be using raid5), and that the devices are always in the same order, etc -then go ahead.
If you have one machine that has a failure on a drive, only this machine will do the appropriate thing - leaving the others with a view of the device that is inconsistent with that of the machine on which the failure took place. This is the fundamental problem.
brassow On Oct 7, 2004, at 11:07 AM, Ed L Cashin wrote:
Erling Nygaard <nygaard@xxxxxxxxxx> writes:
No, this will not work at all.
All GFS locking is done on a filesystem level. In order to make this work
you need locking on the blocksystem level .
I guess I'm looking for a concrete reason why it won't work. I've been assuming it won't work, but I can't think of a concrete reason.
You need to lock a resource group to allocate blocks for a file, and you need to lock the file in order to modify its blocks, so it's not entirely clear to me why you need block-level locking when md is involved.
The only concrete problem I can think of is that the md has a superblock, and no node would know that other nodes are using the same md superblock.
-- Ed L Cashin <ecashin@xxxxxxxxxx>
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