[PATCH, RFC] mkfs.xfs: go into multidisk mode when geometry is on cmdline
In the course of some other investigations, I found that
calc_default_ag_geometry() doesn't go into "multidisk" mode
unless stripe geometry is *detected* (i.e. by the blkid routines).
Specifying a geometry on the cmdline is *not* sufficient, because
we test (ft.dsunit | ft.dswidth) which are not set by the cmdline
If we move the AG calculations to after we have set dsunit & dswdith,
then we'll pick up either cmdline-specified or blkid-detected
geometry, and go into "multidisk" mode for AG size/count
calculations in both cases.
So now for a ~5T fs, for example, we'd make several more
Re: [PATCH, RFC] mkfs.xfs: go into multidisk mode when geometry is on cmdline
On Tue, Nov 20, 2012 at 10:34:29AM -0600, Eric Sandeen wrote:
> So now for a ~5T fs, for example, we'd make several more
> # truncate --size=5t fsfile
> # mkfs.xfs -N -d su=128k,sw=8 fsfile | grep agcount
> meta-data=fsfile isize=256 agcount=5, agsize=268435424 blks
> # mkfs/mkfs.xfs -N -d su=128k,sw=8 fsfile | grep agcount
> meta-data=fsfile isize=256 agcount=32, agsize=41943008 blks
Can you add this to xfstests, please?
> TBH, though, is there ever any value in treating a very large
> fs as "!multidisk?" When would we ever want to pretend that
> a 16T filesystem doesn't have a lot of spindles behind it?
Not now, but I'm pretty sure we'll get there not too soon in the