fsck, glabel and sudden paralellism

[Ivan Voras]

Andriy Gapon wrote:
> So I recently switched one system to have only (g)labels instead of "raw" device
> names in fstab and noticed that now initial (preen) fsck is performed in parallel
> on couple of filesystems where before it used to be sequential.
> 
> Here is a lengthy quote from fsck(8):
>> In preen mode, after pass 1 completes, all remaining file systems are
>> checked, in pass number order running one process per disk drive in par-
>> allel for each pass number in increasing order.
>>
>> In other words: In preen mode all pass 1 partitions are checked sequen-
>> tially.  Next all pass 2 partitions are checked in parallel, one process
>> per disk drive.  Next all pass 3 partitions are checked in parallel, one
>> process per disk drive.  etc.
>>
>> The disk drive containing each file system is inferred from the shortest
>> prefix of the device name that ends in a digit; the remaining characters
>> are assumed to be the partition and slice designators.
> 
> I think it is highly desirable that fsck knows which filesystems reside on the
> same disk regardless of how they are referred to.
> I think that the simple string matching described above is not sufficient these days.
> Is there an easy geom way to query this info?

Yes, contents of kern.geom.confxml could be used to walk the tree of
GEOM devices and find what drive they are physically on.

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