Re: [dm-devel] FS directly on top of dm devices?

[Scott Dungan <scott gps caltech edu>]

Stripe alignment was the benefit we were thinking as well. These devices 
will be used for ext3 file systems that will store a mix of file sizes 
and types that are accessed by user-written and executed applications on 
an HPC cluster.

It is difficult to tune the file system or the underlying SAN LUNs for 
such a mix, so we are choosing our best estimate for general i/o.

It is comforting to know that others are using no partitioning.

Thanks.



Christopher Chen wrote:
> I run md over mpath dm'd devices, without partitioning. Of course, I
> use dm-multipath to reach individual disks in a JBOD with two FC-AL
> loops.
>
> Lots of people like to do this to preserve stripe alignment.
>
> I also use LVM, with the metadatasize option on creation of the PV, to
> preserve stripe alignment.
>
> Do you have a specific application in mind, like a database?
>
> On Thu, Apr 16, 2009 at 4:52 PM, Scott Dungan <scott gps caltech edu> wrote:
>   
> > We recently had an engineer from a large storage vendor suggest that we make
> > our file systems directly onto the multipathed devices without first
> > creating underlying partitions or using LVM.  Having not run with this
> > method in production before, we would like to gather as much information as
> > possible first. Initial searches for documentation on this method has
> > produced few results, short of a Suse/Novell document from 2005 under
> > section 4:
> >
> > http://support.novell.com/techcenter/sdb/en/2005/04/sles_multipathing.html
> >
> > Does anyone have any experience with this or can point us to more
> > documentation. thoughts or recommendations?
> >
> > Thanks,
> >
> > --
> >
> > Scott A Dungan
> >
> >
> > --
> > dm-devel mailing list
> > dm-devel redhat com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >
> >     
>
>
>
>   

--

Scott A Dungan
Systems Administrator
GPS Division
California Institute of Technology
Phone: (626) 395-3170
Fax:   (626) 585-1917