Stress testing the UFS2 filesystem

[Pavel Merdine]

Hello ,



Wednesday, May 3, 2006, 2:13:07 AM, you wrote:

> On Wed, May 03, 2006 at 12:32:29AM +0400, Pavel Merdine wrote:
>> Hello ,
>> 
>> Thank you for raising this problem again. I already tried to do that
>> in that list, but received an answer that kernel is intended to do
>> that. For example, you have a faulty disk. And you have a faulty
>> sector which happened to occur on the directory place. So each time
>> kernel reads this sector it panics. So it's initially hard to even
>> understand what happens. And also it leads to corruption and lost
>> files on other file system (each time). Imagine if you have 15 disks.
>> In this case you have many files lost just because of a small (and not
>> significant) fault. It's just a nonsense.
>> Personally, I just replaced bad_dir with error return.
>> By the way, there was some bug in fs in kernel that could lead to
>> panic even on clean filesystem (bad_dir as far as I remember). It is
>> very rare and it was fixed on DragonFly. As far as I remember a fix
>> for this was also commited to current recently.
>> 
>> I think that Linux is usually much smarter on this. By default it
>> remounts a file system as read-only in case it detects a filesystem
>> corruption. I would be very happy if FreeBSD could do the same,
>> because fs panics really hurt when you have many systems with disks.
>> 
>> Of course I think we could do patches to overcome corrupting panics,
>> but the core FreeBSD team would not accept this, as they are happy
>> with panics and corruptions they make to other filesystems.

> Of course not, don't make silly accusations :-)
> The problem is much more difficult to solve than "making the panic an
> error return".

I think that is you who call me silly. I did not mean what you wrote.
Where did I say that? I just said I made an error return for myself.
And it was a quick patch to stop infinite series of panics (leaded to
hundred files lost). What would you do in that case, very smart and
genius man?

I wrote I would be very happy if FreeBSD could do read-only remounts.

> Kris

-- 
/ Pavel Merdine