[dm-devel] Re: IO scheduler based IO controller V10

[Andy]

On Wed, Oct 07, 2009 at 12:41:27PM -0400, Rik van Riel wrote:
> Ryo Tsuruta wrote:
> 
> >If once dm-ioband is integrated into the LVM tools and bandwidth can
> >be assigned per device by lvcreate, the use of dm-tools is no longer
> >required for users.
> 
> A lot of large data center users have a SAN, with volume management
> handled SAN-side and dedicated LUNs for different applications or
> groups of applications.
> 
> Because of alignment issues, they typically use filesystems directly
> on top of the LUNs, without partitions or LVM layers.  We cannot rely
> on LVM for these systems, because people prefer not to use that.
> 

I am one of these people that does not use LVM, because I have no need to
with the SAN.  The SAN spreads the volume across many disks, I do not need
to do it.  LVM would add layers of complexity than I do not need.  I do use
currently use EVMS to allow me to expand volumes without rebooting.  But,
with the newer kernels I do not even need that since I can just expand the
LUN and the the filesystem (I do not use partitions either).  Why was
device-mapper stuff moved into LVM2? IMHO it should have stayed separate.

Andy