graid often resyncs raid1 array after clean reboot/shutdown

[Lawrence Stewart]

Hi Alexander,

On 10/30/12 01:25, Alexander Motin wrote:
> On 29.10.2012 11:17, Alexander Motin wrote:
>> On 29.10.2012 10:29, Alexander Motin wrote:
>>> Hi.
>>>
>>> On 29.10.2012 06:55, Lawrence Stewart wrote:
>>>> I have a fairly new HP Compaq 8200 Elite desktop PC with 2 x 1TB
>>>> Seagate
>>>> ST1000DM003 HDDs in raid1 using the on-board Intel Matrix RAID
>>>> controller. The system is configured to boot from ZFS off the raid1
>>>> array, and I use it as a KDE GUI (with on-cpu GPU + KMS) desktop.
>>>>
>>>> Everything works great, except that after a "shutdown -r now" of the
>>>> system, graid almost always (I believe I've noted a few times where
>>>> everything comes up fine) detects one of the disks in the array as
>>>> stale
>>>> and does a full resync of the array over the course of a few hours.
>>>> Here's an example of what I see when starting up:
>>>
>>>  From log messages it indeed looks like result of unclean shutdown. I've
>>> never seen such problem with UFS, but I never tested graid with ZFS. I
>>> guess there may be some difference in shutdown process that makes RAID
>>> metadata to have dirty flag on reboot. I'll try to reproduce it now.
>>
>> I confirm the problem. Seems it happens only when using ZFS as root file
>> system. Probably ZFS issues some last moment write that makes volume
>> dirty. I will trace it more.
> 
> I've found problem in the fact that ZFS seems doesn't close devices on
> shutdown. That doesn't allow graid to shutdown gracefully. r242314 in
> HEAD fixes that by more aggressively marking volumes clean on shutdown.

Thanks for the quick detective work and fix. I'll merge r242314 back to
my local stable/9 tree and test it.

Cheers,
Lawrence