https://jira.whamcloud.com This file is an XML representation of an issue en-us 9.4.14 940014 05-12-2023 https://jira.whamcloud.com/browse/LU-9462 Lustre <p>"lfs setstripe" should support --component-add/del operations on a directory.</p> LU-9462

"lfs setstripe" doesn't support --component-add/del on a directory

Improvement Minor Resolved Fixed Emoly Liu Emoly Liu Mon, 8 May 2017 04:16:54 +0000 Wed, 25 Oct 2017 22:57:18 +0000 Mon, 16 Oct 2017 13:38:23 +0000 Lustre 2.10.0 Lustre 2.11.0 Lustre 2.10.2 0 6 <p>"--component-add/del" was introduced to modify file layout incrementally, so that user can change the file layout and preserve the existing data at the same time. I don't think it's necessary for default layout, because user can simply change the current default layout by 'lfs setstripe' without worrying data loss, and I personally think one call to "lfs setstripe $newlayout dir" is simpler than many calls to "lfs setstripe --component-add/del $deltalayout dir".</p> <p>I'm not totally against this feature, I think It's nice to have, but there is a problem needs be addressed beforehand: current component-del can only delete component by component ID or flags, that are not valid for a default layout, so what kind of argument should be specified for deleting a component of default layout? Using index of component (the index of component array in LOVEA) could be a solution, but it requires 'lfs getstripe' to print an 'index' for each component, and it needs we to put the array index in protocol, that looks not quite clean to me.</p> <p>Andreas, Bobi, any good idea? Thanks in advance.</p> <p>Another solution is that when using 'lfs --component-del' to a directory, ignore other arguments, and we just always delete the last component internally. The bad side of this approach is that it complicated the usage and looks bit confusing.</p> <p>Both approaches need quite a few code changes in LOD to make the functions to support directory, so I tend to think that we shouldn't take effort to implement this. What we need to do is to explain it well in Lustre manual, so that user won't be confused, I think the comment in manual could be:</p> <p>"default layout in directory is like config, it can be arbitrarily changed by 'lfs setstripe', layout in file may have data (OST objects) attached, if user want to expand/shrink layout while preserving the data on untouched component, he can use 'lfs setstripe --component-add/del."</p> <p>Does it sound ok? If no objections, I'm going to close this ticket as 'won't fix'. Thanks.</p> <blockquote> <p>default layout in directory is like config, it can be arbitrarily changed by 'lfs setstripe', layout in file may have data (OST objects) attached, if user want to expand/shrink layout while preserving the data on untouched component, he can use 'lfs setstripe --component-add/del.</p></blockquote> <p>Sorry, I don't understand this. It isn't clear to me what <tt>&#45;&#45;component&#45;add/del</tt> on a regular file have to do with the same on a directory? I'm OK with not implementing this feature, now that I realize that "<tt>lfs setstripe</tt>" on the directory can be used to replace the entire layout immediately. I guess this is a bit more effort than editing the layout for a regular file, but with the <tt>--yaml</tt> option it should be enough.</p> <p>Definitely there needs to be some discussion of this in the <tt>lfs-setstripe.1</tt> man page and in the user manual.</p> <blockquote> <p>Sorry, I don't understand this. It isn't clear to me what --component-add/del on a regular file have to do with the same on a directory? I'm OK with not implementing this feature, now that I realize that "lfs setstripe" on the directory can be used to replace the entire layout immediately. I guess this is a bit more effort than editing the layout for a regular file, but with the --yaml option it should be enough.<br/> Definitely there needs to be some discussion of this in the lfs-setstripe.1 man page and in the user manual.</p></blockquote> <p>Yes, I didn't explain it well, my point is that if we explain the purpose of "--component-add/del" clearly in Lustre manual, user won't run into the confusion of "why can't I apply this command to directory?"</p> <p>I added some words to this effect into my patch <a href="https://review.whamcloud.com/27066" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/27066</a> "<tt><a href="https://jira.whamcloud.com/browse/LU-9324" title="sanity-pfl test 10 needs to reset the file system default layout" class="issue-link" data-issue-key="LU-9324"><del>LU-9324</del></a> doc: update lfs setstripe man page and usage</tt>":</p> <blockquote> <p>lfs setstripe <span class="error">&#91;STRIPE_OPTIONS&#93;</span> &lt;directory|filename&gt;</p> <p>Create a file with specified layout, or set <b>or replace</b> the default file<br/> layout on an existing directory.</p></blockquote> <p>This could be expanded a bit further. That patch will likely need to be refreshed due to conflicts as other PFL patches land, so it can be added in one of the updates.</p> <p>Is there an update on this?  Just did not want it to get lost.  Thanks!</p> <p>Minor documentation patch needed for this (which I just updated), not critical for the release. It also needs an update to the user manual to make it clear that changing the default layout on a directory cannot be done with "<tt>&#45;&#45;component&#45;add</tt>" or "<tt>&#45;&#45;component&#45;del</tt>", but rather the whole layout needs to be rewritten, or dumped and restored via "<tt>lfs getstripe &#45;&#45;yaml</tt>" and "<tt>lfs setstripe &#45;&#45;yaml</tt>" (<a href="https://jira.whamcloud.com/browse/LU-9324" title="sanity-pfl test 10 needs to reset the file system default layout" class="issue-link" data-issue-key="LU-9324"><del>LU-9324</del></a>).</p> <p>Oleg Drokin (oleg.drokin@intel.com) merged in patch <a href="https://review.whamcloud.com/27066/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/27066/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9462" title="&quot;lfs setstripe&quot; doesn&#39;t support --component-add/del on a directory" class="issue-link" data-issue-key="LU-9462"><del>LU-9462</del></a> doc: update lfs setstripe man page and usage<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: aa83ef5a9ec470d2f6af07d47b3dd763f4a0e7ce</p> <p>Landed for 2.11</p> <p>Minh Diep (minh.diep@intel.com) uploaded a new patch: <a href="https://review.whamcloud.com/29627" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/29627</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9462" title="&quot;lfs setstripe&quot; doesn&#39;t support --component-add/del on a directory" class="issue-link" data-issue-key="LU-9462"><del>LU-9462</del></a> doc: update lfs setstripe man page and usage<br/> Project: fs/lustre-release<br/> Branch: b2_10<br/> Current Patch Set: 1<br/> Commit: 6a4b611a2db00f220aa48077ea017fc79fd239b2</p> <p>John L. Hammond (john.hammond@intel.com) merged in patch <a href="https://review.whamcloud.com/29627/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/29627/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9462" title="&quot;lfs setstripe&quot; doesn&#39;t support --component-add/del on a directory" class="issue-link" data-issue-key="LU-9462"><del>LU-9462</del></a> doc: update lfs setstripe man page and usage<br/> Project: fs/lustre-release<br/> Branch: b2_10<br/> Current Patch Set: <br/> Commit: 27041128dbdced3975185fefcbddb304a1bb21cd</p> Related LU-9349 Development Rank 1|hzzc2n: Rank (Obsolete) 9223372036854775807