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<div class="">On Mar 16, 2023, at 17:02, Jeff Johnson <<a href="mailto:jeff.johnson@aeoncomputing.com" class="">jeff.johnson@aeoncomputing.com</a>> wrote:</div>
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<div class="">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
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<div class="">dd if=/dev/zero of=/my_lustre_mountpoint/some_subdir/big_raw_file bs=1048576 count=100000</div>
<div class="">losetup -f /my_lustre_mountpoint/some_subdir/big_raw_file</div>
<div class="">*assuming loop0 is created*</div>
<div class="">some_fun_command /dev/loop0 </div>
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Note with ldiskfs backends you can use "fallocate -l 100000M /my_lustre_mountpoint/some_subdir/big_raw_file" to reserve the space.</div>
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<div>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.</div>
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<div class="">Disclaimer: Just because you *can* do this, doesn't necessarily mean it is a good idea</div>
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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.</div>
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<div>Cheers, Andreas</div>
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<div dir="ltr" class="gmail_attr">On Thu, Mar 16, 2023 at 3:29 PM Mohr, Rick via lustre-discuss <<a href="mailto:lustre-discuss@lists.lustre.org" class="">lustre-discuss@lists.lustre.org</a>> wrote:<br class="">
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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.<br class="">
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On 3/16/23, 3:44 PM, "lustre-discuss on behalf of Shambhu Raje via lustre-discuss" <<a href="mailto:lustre-discuss-bounces@lists.lustre.org" target="_blank" class="">lustre-discuss-bounces@lists.lustre.org</a> <mailto:<a href="mailto:lustre-discuss-bounces@lists.lustre.org" target="_blank" class="">lustre-discuss-bounces@lists.lustre.org</a>>
on behalf of <a href="mailto:lustre-discuss@lists.lustre.org" target="_blank" class="">
lustre-discuss@lists.lustre.org</a> <mailto:<a href="mailto:lustre-discuss@lists.lustre.org" target="_blank" class="">lustre-discuss@lists.lustre.org</a>>> wrote:<br class="">
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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'.<br class="">
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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??<br class="">
Can share command??<br class="">
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<span class="gmail_signature_prefix">-- </span><br class="">
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<div dir="ltr" class="">------------------------------<br class="">
Jeff Johnson<br class="">
Co-Founder<br class="">
Aeon Computing<br class="">
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<a href="mailto:jeff.johnson@aeoncomputing.com" target="_blank" class="">jeff.johnson@aeoncomputing.com</a><br class="">
<a href="http://www.aeoncomputing.com/" target="_blank" class="">www.aeoncomputing.com</a><br class="">
t: 858-412-3810 x1001 f: 858-412-3845<br class="">
m: 619-204-9061<br class="">
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4170 Morena Boulevard, Suite C - San Diego, CA 92117
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<div class="">High-Performance Computing / Lustre Filesystems / Scale-out Storage</div>
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<div>Cheers, Andreas</div>
<div>--</div>
<div>Andreas Dilger</div>
<div>Lustre Principal Architect</div>
<div>Whamcloud</div>
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