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-9162 Lustre <p>We have users that will set stripe count by using "-1" as in <br/> lfs setstripe -c -1</p> <p>Filesystem with small number of OSTs (~200) this was ok. But as our OST count get lager (&gt;400) this is not always desirable. Most of the time we don't want our users to set stripe counts so large. We would like config option for max default size setting for (lfs setstripe -c -1). But would still like the ability to allow setting stripe counts upto LOV_MAX_STRIPE_COUNT for those who really need it.</p> LU-9162

Option to set max stripe count per filesystem

New Feature Major Resolved Fixed Feng Lei Mahmoud Hanafi easy Mon, 27 Feb 2017 17:37:44 +0000 Fri, 10 Mar 2023 19:53:51 +0000 Tue, 30 Nov 2021 13:46:28 +0000 Lustre 2.7.0 Lustre 2.15.0 0 12 <p>Mahmoud</p> <p>Is this something that you are working on or more of a suggestion for an enhancement? We discussed this a little on the daily engineering call and the feeling was that this could be a useful change though there would still need to be some consideration given to be able to override this behaviour.</p> <p>Peter</p> <p>Peter, <br/> This is an area we can do the development but we would like some guidance about how the config option should be stored.</p> <p>Mahmoud, I just noticed this ticket when searching for another issue.</p> <p>It looks like this would be relatively straight forward to do. It looks like what would be needed is to add a /proc tunable to specify e.g. <tt>maximum_stripe_count</tt> (0 if no limit), and add another check into <tt>lod_get_stripe_count()</tt>, something like:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"> <span class="code-keyword">if</span> (stripe_count &gt; lod-&gt;lod_desc.ld_active_tgt_count) { <span class="code-keyword">if</span> (lod-&gt;lod_max_stripe_count &amp;&amp; lod-&gt;lod_max_stripe_count &lt; lod-&gt;lod_desc.ld_active_tgt_count) stripe_count = lod-&gt;lod_max_stripe_count; <span class="code-keyword">else</span> stripe_count = lod-&gt;lod_desc.ld_active_tgt_count; } </pre> </div></div> <p>lod_desc is origially a readonly struct so there is no lock protection on it. If we add a changable field ld_max_stripe_count into it, we need a lock to protect it anywhere it's accessed. Is it too expensive?</p> <p>one more question is where to put the lock?</p> <p><a href="https://jira.whamcloud.com/secure/ViewProfile.jspa?name=flei" class="user-hover" rel="flei">flei</a>, I don't think this needs locking, because it is "racy" even with a lock. The value could be accessed a microsecond before or after the value is changed by the user, so having a lock won't help that. It will only affect the one file being created at the time it is checked, and does not really need to be consistent from one file to the next. </p> <p>Also, this does not really need to be part of lov_desc, which was the old/original way to set the default "plain" layout of the filesystem, but has been deprecated with the introduction of more complex PFL/FLR layouts. It would be better to make this a normal sysfs tunable that can be set with "<tt>lctl set_param <span class="error">&#91;-P&#93;</span> lod.&#42;.max_stripe_count</tt>". </p> <p>Is is OK to make the max_stripe_count a member of lod_device?</p> <p>Yes, definitely. You can copy <tt>stripeoffset_show()</tt> and <tt>stripeoffset_store()</tt> to print/store the parameter in lod_device.</p> <p>"Feng, Lei &lt;flei@whamcloud.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/45532" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/45532</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9162" title="Option to set max stripe count per filesystem" class="issue-link" data-issue-key="LU-9162"><del>LU-9162</del></a> lod: option to set max stripe count per filesystem<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 80534f98629dedaeb381757e97f8c9d7bf62ac0c</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/45532/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/45532/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-9162" title="Option to set max stripe count per filesystem" class="issue-link" data-issue-key="LU-9162"><del>LU-9162</del></a> lod: option to set max stripe count per filesystem<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 3c9580931d1a7753e6c03900df01fd05ab3ca73d</p> <p>Landed for 2.15</p> Cloners LU-15307 Related LU-13748 LU-6689 LUDOC-501 Development Rank 1|hzz57z: Rank (Obsolete) 9223372036854775807