Re: 2.6.15-mm2

From: Neil Brown
Date: Wed Jan 11 2006 - 16:43:25 EST


On Wednesday January 11, axboe@xxxxxxx wrote:
>
> Then the barrier changes from git2 -> git3 should not have anything to
> do with it. Strange... I guess you should try the git bisect method to
> narrow it down.

Not true, though you seem to have already figured that out.

md uses barrier writes when writing the superblock. This is partly
because it seems like a good idea, but largely to test if barrier
writes are going to work on the component devices. If any device
claims not to support barriers, then raid1 will claim not to support
barriers.

And the strange hang happens while md is trying to update the
superblock.

NeilBrown
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