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-14912 Lustre <p>When server indicates it supports T10 checksums, the client could still pick other check types over T10PI as the other types getting better numbers during client benchmark.</p> LU-14912

client picking other checksum type over T10PI

Improvement Minor Resolved Fixed Dongyang Li Dongyang Li Thu, 5 Aug 2021 12:50:10 +0000 Tue, 17 May 2022 15:09:21 +0000 Wed, 25 Aug 2021 16:40:30 +0000 Lustre 2.15.0 0 4 <p>T10-PI checksums were only added in 2.12, so I don't think it is reasonable for the server to return <b>only</b> a single <tt>t10crc4K</tt> checksum type, because this would break interoperability for 2.10.x clients.</p> <p>One option for selecting the proper T10-PI checksum type automatically on the client, is to detect if only a <b>single</b> <tt>OBD_CKSUM_T10&#42;</tt> type is returned to the client, then this indicates the server has T10-PI enabled (otherwise it would return multiple <tt>OBD_CKSUM_T10&#42;</tt> types), and it should prefer this over other checksum types.</p> <p>For example, on my test VM (no T10-PI support in the storage) it reports multiple <tt>t10&#42;</tt> checksum types enabled:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre># lctl get_param osc.*.checksum_type osc.testfs-OST0000-osc-ffff9ac928b3d800.checksum_type= crc32 adler crc32c t10ip512 [t10ip4K] t10crc512 t10crc4K </pre> </div></div> <p>while on a client where T10-PI hardware support is enabled on the server the client reports:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre># lctl get_param osc.*.checksum_type osc.testfs-OST0000-osc-ffff9ac928b3d800.checksum_type= crc32 adler [crc32c] t10crc4K </pre> </div></div> <p>In this case, the client should prefer the single <tt>t10crc4K</tt> checksum type (if no type was specified) that matches the server hardware checksum type, even though <tt>crc32c</tt> may be somewhat faster.</p> <p>"Li Dongyang &lt;dongyangli@ddn.com&gt;" uploaded a new patch: <a href="https://review.whamcloud.com/44657" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/44657</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-14912" title="client picking other checksum type over T10PI" class="issue-link" data-issue-key="LU-14912"><del>LU-14912</del></a> obdclass: prefer T10 checksum if the target supports it<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: 1<br/> Commit: 0c6d2cf5b4cc449253965cbd527e6a2f6ef0ee3e</p> <p>"Oleg Drokin &lt;green@whamcloud.com&gt;" merged in patch <a href="https://review.whamcloud.com/44657/" class="external-link" target="_blank" rel="nofollow noopener">https://review.whamcloud.com/44657/</a><br/> Subject: <a href="https://jira.whamcloud.com/browse/LU-14912" title="client picking other checksum type over T10PI" class="issue-link" data-issue-key="LU-14912"><del>LU-14912</del></a> obdclass: prefer T10 checksum if the target supports it<br/> Project: fs/lustre-release<br/> Branch: master<br/> Current Patch Set: <br/> Commit: 5e9059e08aec6fb36de6788465978de0e962b956</p> <p>Landed for 2.15</p> Related LU-14924 LU-10472 LU-14895 LU-11011 Development Rank 1|i020zb: Rank (Obsolete) 9223372036854775807