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

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.


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

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:


Does anyone have any experience with this or can point us to more
documentation. thoughts or recommendations?



Scott A Dungan

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

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