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-11916 Lustre <p>I was trying to use "LSOM enforced" on a 2.12 client (for testing purpose, not very important), and noticed the lazy_stat option doesn't seem to work:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>[794713.969118] LustreError: 152-6: Unknown option 'lazy_stat', won't mount. </pre> </div></div> <p>This new mount option was mentioned in Li Xi's presentation at LUG'18 (page 7) <a href="http://cdn.opensfs.org/wp-content/uploads/2018/04/Xi-Lazy_Size_on_MDS_DDN.pdf" class="external-link" target="_blank" rel="nofollow noopener">http://cdn.opensfs.org/wp-content/uploads/2018/04/Xi-Lazy_Size_on_MDS_DDN.pdf</a></p> <p>Is there a way to enforce LSOM on a Lustre client, or not yet?<br/> Thanks!<br/> Stephane</p> CentOS 7.6, MOFED 4.5 LU-11916

LSOM: lazy_stat mount option not recognized

Bug Minor Resolved Won't Fix Qian Yingjin Stephane Thiell Fri, 1 Feb 2019 23:10:46 +0000 Fri, 15 May 2020 16:27:48 +0000 Fri, 15 May 2020 14:38:25 +0000 Lustre 2.12.0 0 4 <p>Qian</p> <p>Can you comment as to whether this was included in the feature as it ended up in 2.12?</p> <p>Peter</p> <p>The "<tt>lazy_stat</tt>" mount option is not in the 2.12 release. The closest is patch <a href="https://review.whamcloud.com/33412" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/33412</a><br/> "<tt><a href="https://jira.whamcloud.com/browse/LU-11554" title="Make stat() work with LSOM" class="issue-link" data-issue-key="LU-11554"><del>LU-11554</del></a> som: Make stat() work with LSOM</tt>", but it also is not yet landed, since it isn't clear what the usage implications are.</p> <p>The current LSOM implementation isn't just "the size is a bit outdated", it is "the size and blocks stored on the MDS are zero until after the file is closed", so this would likely break many applications, and this can only be set on a per-mountpoint basis.</p> <p>Could you explain more how you want to us LSOM? The current implementation is mostly intended for MDT-level scanning. There is also a patch to add support for "<tt>lfs find</tt>" that is fairly safe, and discussion around adding support for <tt>statx()</tt>, which is what I think applications should use when they want the lazy size.</p> <p>For RBH usage, the 33412 patch and a separate mountpoint may be enough, as long as you don't trust the size on recently-created files.</p> <p>Thanks Andreas for the information and pointers, this is super helpful. I understand the interest of LSOM for MDT-level scanning, but I wanted to see how it would break (or not) applications if also enforced for (regular) <tt>stat()</tt>. <img class="emoticon" src="https://jira.whamcloud.com/images/icons/emoticons/wink.png" height="16" width="16" align="absmiddle" alt="" border="0"/> So no real life use-case at the moment, but I'll think about it during the weekend.</p> <p>The <tt>statx()</tt> API is going to land soon, and "<tt>lfs find</tt>" already can understand LSOM.</p> <p>Excellent, thanks!</p> Related LU-10934 LU-11554 Development Rank 1|i00auv: Rank (Obsolete) 9223372036854775807 Severity