I never got an answer to two issues regarding large logical volumes:
> Did this issue ever get resolved:
>
> > I've experimented with vol group sizes from 1.4TB to 800GB. With the
> > less-than-1TB size, I experimented with vol group PE sizes from 8M to
> > 16M to 32M.
> > The vol group is 633600MB
> > PE size of 8M, I can only stripe logical vols under 100GB in size.
> > PE size of 16M, the largest logical vol with striping is 103GB (105600
MB).
> > PE size of 32M, same as 16M PE, 103GB.
>
> I also recall an issue of mke2fs failing to make a file system of a
logical volume 1TB or larger. Was that ever resolved?
On the first issue, I believe I have the answer which may be surprising. To
utilize all of the space of a striped volume group, the number of stripes
must be set equal to the number of phsical volumes. So for example. if you
want a 2TB striped LVM consisting of 98 3390-27s, you must use 98 stripes.
On the surface this may seem like too many stripes for good performance,
but perhaps the LVM code is smarter than that. Can anyone who knows the
LVM code comment?
On the second issue, logical volumes larger than 1TB, the most DASD I can
seem to muster is in the tens of GBs range (just because IBM has gobs of
hardware doesn't mean everyone can own what they want :)), so I can't test.
Has anyone created a file system from a 1-2TB logical volume (2TB seems to
be the limit for Linux block devices)? ext3, reiserfs?
Thanks.
-Mike MacIsaac, IBM mikemac at us.ibm.com (845) 433-7061
