Re: Intel fakeraid working?

[NeilBrown <neilb@suse.de>]

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On Wed, 04 Apr 2012 20:56:48 -0400 Phillip Susi <psusi@ubuntu.com> wrote:

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> I was trying to use mdadm to activate an intel fakeraid last night and mdadm insisted on activating it as read-only.  I could not get it to switch to read-wrte.  Today I came across this bug:
> 
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/972960

That bug is fixed by 

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=c744a65c1e2d59acc54333ce80a5b0702a98010b

and is not specific to Intel IMSM RAID.

(I personally don't like the term 'fakeraid' - there is nothing fake about
it.  Firmware RAID is a suitable term).

I believe Intel RAID works and it certainly works in my tests, but they are
fairly limited.  Intel do much broader testing and they seem to be reasonably
happy with it.

If the array was activated read-only, that suggests that 'mdmon' didn't run.
mdmon is a daemon which monitors the array and updates the metadata as
needed.  until it is running it is not safe for the array to be writable.
However it should be started automatically by mdadm.

How are you attempting to start the array?

NeilBrown


> 
> It seems that the kernel OOPSed here:
> 
> void md_write_start(struct mddev *mddev, struct bio *bi)
> {
> 	int did_change = 0;
> 	if (bio_data_dir(bi) != WRITE)
> 		return;
> 
> 	BUG_ON(mddev->ro == 1);
> 
> It appears this is because it wanted to update the metadata, but the array was read-only, so I thought this might be related to what I was seeing, and there is a bug that is preventing the array from correctly going read-write.
> 
> Is the Intel fakeraid support actually working yet, or still in development?
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