On Mar 16, 2023, at 17:02, Jeff Johnson
<[email protected]<mailto:[email protected]>> wrote:
If you *really* want a block device on a client that resides in Lustre you
*could* create a file in Lustre and then make that file a loopback device with
losetup. Of course, your mileage will vary *a lot* based on use case, access,
underlying LFS configuration.
dd if=/dev/zero of=/my_lustre_mountpoint/some_subdir/big_raw_file bs=1048576
count=100000
losetup -f /my_lustre_mountpoint/some_subdir/big_raw_file
*assuming loop0 is created*
some_fun_command /dev/loop0
Note with ldiskfs backends you can use "fallocate -l 100000M
/my_lustre_mountpoint/some_subdir/big_raw_file" to reserve the space.
Alternately, if you have flash-based OSTs you could truncate a sparse file to
the full size ("truncate -S 100000M ...") and format that, which will not
consume as much space but will generate more random allocation on the OSTs.
Disclaimer: Just because you *can* do this, doesn't necessarily mean it is a
good idea
We saw a good performance boost with ext4 images on Lustre holding many small
files (CCI). Also, I recall some customers in the past using ext2 or ext4
images effectively to aggregate many small files for read-only use on compute
nodes.
Cheers, Andreas
On Thu, Mar 16, 2023 at 3:29 PM Mohr, Rick via lustre-discuss
<[email protected]<mailto:[email protected]>> wrote:
Are you asking if you can mount Lustre on a client so that it shows up as a
block device? If so, the answer to that is you can't. Lustre does not appear
as a block device to the clients.
-Rick
On 3/16/23, 3:44 PM, "lustre-discuss on behalf of Shambhu Raje via
lustre-discuss"
<[email protected]<mailto:[email protected]>
<mailto:[email protected]<mailto:[email protected]>>
on behalf of
[email protected]<mailto:[email protected]>
<mailto:[email protected]<mailto:[email protected]>>>
wrote:
When we mount a lustre file system on client, the lustre file system does not
use block device on client side. Instead it uses virtual file system namespace.
Mounting point will not be shown when we do 'lsblk'. As it only show on 'df-hT'.
How can we mount lustre file system on block such that when we write something
with lusterfs then it can be shown in block device??
Can share command??
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--
------------------------------
Jeff Johnson
Co-Founder
Aeon Computing
[email protected]<mailto:[email protected]>
www.aeoncomputing.com<http://www.aeoncomputing.com/>
t: 858-412-3810 x1001 f: 858-412-3845
m: 619-204-9061
4170 Morena Boulevard, Suite C - San Diego, CA 92117
High-Performance Computing / Lustre Filesystems / Scale-out Storage
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Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Whamcloud
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