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-15314 Lustre <p>From <a href="https://jira.whamcloud.com/browse/LU-15307" title="Option to set max directory stripe count per filesystem" class="issue-link" data-issue-key="LU-15307"><del>LU-15307</del></a> by <a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=adilger" class="user-hover" rel="adilger">adilger</a><br/>  <br/> In addition to limiting the stripe count used when selecting "<tt>-c -1</tt>" it also makes sense to return an error from "<tt>lfs setdirstripe</tt>" when creating a <b>default</b> directory striping that has a stripe count &gt; 1 but does not have max-inherit set. There have repeatedly been problems hit when a filesystem is configured with "<tt>lfs setdirstripe -c N -D $MOUNT</tt>" (for any <tt>N</tt> &gt; 1) causing <tt>REMOTE_PARENT_DIR</tt> to be filled or have tens of millions of entries, excessive MDT inode usage, performance issues, etc.</p> <p>With automatic DNE MDT space balancing (<a href="https://jira.whamcloud.com/browse/LU-13440" title="DNE3: limit directory default layout inheritance" class="issue-link" data-issue-key="LU-13440"><del>LU-13440</del></a>) the need to stripe directories by default is almost completely eliminated. It should still be possible to set this by explicitly specifying <tt>--max-inherit=N</tt>, but this is too dangerous to let users shoot themselves in the foot by accident by what "seems" like a good idea but is actually very bad over time.<br/> <a href="https://jira.whamcloud.com/secure/EditComment!default.jspa?id=67407&amp;commentId=319925" class="external-link" rel="nofollow">Edit</a></p> LU-15314

set default max-inherit to 3 for default dir stripe policy if stripe count is not 0 or 1

New Feature Critical Resolved Fixed Feng Lei Feng Lei easy Fri, 3 Dec 2021 11:02:26 +0000 Wed, 26 Jan 2022 16:28:10 +0000 Tue, 11 Jan 2022 14:16:54 +0000 Lustre 2.7.0 Lustre 2.15.0 0 6 <p>I would suggest to set the default value of <tt>&#45;&#45;max-inherit</tt> to a fixed value (e.g., 3) instead of unlimited (-1) for <tt>lfs setstripe -D -c N</tt> command. But if <tt>&#45;&#45;max-inherit</tt> is specified explicitly, its value will always be accepted. A warning message can be printed too to notify the user the default value of <tt>&#45;&#45;max-inherit</tt>.</p> <p>This behavior won't change anything on a running system, and won't block existing script to deploy a new system. Even the new system will be a little different from the old ones.</p> <p>But if we make <tt>&#45;&#45;max-inherit</tt> mandatory, some existing scripts may be blocked if they do not provide <tt>&#45;&#45;max-inherit</tt>.</p> <p><a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=adilger" class="user-hover" rel="adilger">adilger</a>  Please feel free to comment.</p> <blockquote> <p>I would suggest to set the default value of <tt>&#45;&#45;max&#45;inherit</tt> to a fixed value (e.g., 3) instead of unlimited (<tt>&#45;1</tt>) for "<tt>lfs setstripe &#45;D &#45;c N</tt>" command. But if <tt>&#45;&#45;max&#45;inherit</tt> is specified explicitly, its value will always be accepted. A warning message can be printed to notify the user the default value of <tt>&#45;&#45;max&#45;inherit</tt>.</p></blockquote> <p>I think this would be a reasonable (and safe) option as well, given the consequences . Having a limited inheritance ("<tt>LMV_INHERIT_DEFAULT = 3</tt>") for default directory layouts with "<tt>stripe_count != 0,1</tt>" avoids users shooting themselves in the foot. "<tt>lfs setdirstripe -D</tt>" should print a warning message for layouts with <tt>&#45;&#45;max&#45;inherit=N</tt>, <tt>N &gt; 4</tt> for "<tt>stripe_count != 0,1</tt>". There shouldn't be a warning message printed for default directory layouts with "<tt>stripe_count=0,1</tt>", regardless of <tt>&#45;&#45;max&#45;inherit</tt> used, since this does not cause the same problems as striped directories.</p> <p><a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=chunteraa" class="user-hover" rel="chunteraa">chunteraa</a>, <a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=crusan" class="user-hover" rel="crusan">crusan</a>, <a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=laisiyao" class="user-hover" rel="laisiyao">laisiyao</a>, any feedback on this? When the MDT space balancing/limited layout inheritance was being developed in <a href="https://jira.whamcloud.com/browse/LU-13440" title="DNE3: limit directory default layout inheritance" class="issue-link" data-issue-key="LU-13440"><del>LU-13440</del></a>, I thought it was important to maintain the same behavior for "<tt>lfs setdirstripe -D ...</tt>" as existed before that patch, but in fact the "default striped directories on whole filesystem" behavior is something we <b>don't</b> want to keep.</p> <p>This looks reasonable to me.</p> <p>"Feng, Lei &lt;flei@whamcloud.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/45874" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/45874</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-15314" title="set default max-inherit to 3 for default dir stripe policy if stripe count is not 0 or 1" class="issue-link" data-issue-key="LU-15314"><del>LU-15314</del></a> utils: set default max-inherit to 3<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 7bf5b510a88ce78d5394f3f1ad29bbc2c239196f</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/45874/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/45874/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-15314" title="set default max-inherit to 3 for default dir stripe policy if stripe count is not 0 or 1" class="issue-link" data-issue-key="LU-15314"><del>LU-15314</del></a> utils: set default max-inherit to 3<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 956b4b1e0d9f18c6fe62d84e1c20268363b8159b</p> <p>Landed for 2.15</p> Related LU-15307 LU-14792 LU-13440 LUDOC-501 Development Rank 1|i02bhz: Rank (Obsolete) 9223372036854775807