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-9584 Lustre <p>The filesystem has 312 OSTs. When creating a file like this</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"> lfs setstripe -c -1 testfile2 </pre> </div></div> <p>Gives only 165 OSTs. This is odd since it is not 160 or 312.</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">lfs getstripe testfile2 testfile2 lmm_stripe_count: 165 lmm_stripe_size: 1048576 lmm_pattern: 1 lmm_layout_gen: 0 lmm_stripe_offset: 68 obdidx objid objid group 68 67532793 0x40677f9 0 ....   </pre> </div></div> LU-9584

stripe count defaults to 165

Bug Minor Resolved Not a Bug Jian Yu Mahmoud Hanafi Fri, 2 Jun 2017 00:02:07 +0000 Thu, 29 Jun 2017 13:10:18 +0000 Thu, 29 Jun 2017 13:10:18 +0000 Lustre 2.7.0 0 6 <p>If you have more than 160 OSTs and want to stripe over all of them, then you need to enable the "ea_inode" feature on the MDS, like:<br/> [noformat}<br/> tune2fs -O ea_inode /path/to/MDT</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre></pre> </div></div> <p>Assigning to Jian for any follow on quesitons</p> <p>if we don't have ea_inode option why is it 165 shouldn't be 160</p> <p>Hi Mahmoud,</p> <p>The maximal possible stripe count is calculated based on max EA size in lod_get_stripecnt():</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java">__u16 lod_get_stripecnt(struct lod_device *lod, struct lod_object *lo, __u16 stripe_count) { __u32 max_stripes = LOV_MAX_STRIPE_COUNT_OLD; ...... <span class="code-comment">/* stripe count is based on whether OSD can handle larger EA sizes */</span> <span class="code-keyword">if</span> (lod-&gt;lod_osd_max_easize &gt; 0) { unsigned <span class="code-object">int</span> easize = lod-&gt;lod_osd_max_easize; ...... max_stripes = lov_mds_md_max_stripe_count(easize, LOV_MAGIC_V3); } <span class="code-keyword">return</span> (stripe_count &lt; max_stripes) ? stripe_count : max_stripes; } </pre> </div></div> <p>In lov_mds_md_max_stripe_count():</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"><span class="code-keyword">static</span> inline __u32 lov_mds_md_max_stripe_count(size_t buf_size, __u32 lmm_magic) { ...... <span class="code-keyword">case</span> LOV_MAGIC_V3: { struct lov_mds_md_v3 lmm; <span class="code-keyword">if</span> (buf_size &lt; sizeof(lmm)) <span class="code-keyword">return</span> 0; <span class="code-keyword">return</span> (buf_size - sizeof(lmm)) / sizeof(lmm.lmm_objects[0]); } ...... } </pre> </div></div> <p>And lod-&gt;lod_osd_max_easize is assigned from ddp.ddp_max_ea_size, which is calculated in osd_conf_get() as follows:</p> <div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent"> <pre class="code-java"><span class="code-keyword">static</span> void osd_conf_get(<span class="code-keyword">const</span> struct lu_env *env, <span class="code-keyword">const</span> struct dt_device *dev, struct dt_device_param *param) { struct super_block *sb = osd_sb(osd_dt_dev(dev)); <span class="code-object">int</span> ea_overhead; ........ /* LOD might calculate the max stripe count based on max_ea_size, * so we need take account in the overhead as well, * xattr_header + magic + xattr_entry_head */ ea_overhead = sizeof(struct ldiskfs_xattr_header) + sizeof(__u32) + LDISKFS_XATTR_LEN(XATTR_NAME_MAX_LEN); #<span class="code-keyword">if</span> defined(LDISKFS_FEATURE_INCOMPAT_EA_INODE) <span class="code-keyword">if</span> (LDISKFS_HAS_INCOMPAT_FEATURE(sb, LDISKFS_FEATURE_INCOMPAT_EA_INODE)) param-&gt;ddp_max_ea_size = LDISKFS_XATTR_MAX_LARGE_EA_SIZE - ea_overhead; <span class="code-keyword">else</span> #endif param-&gt;ddp_max_ea_size = sb-&gt;s_blocksize - ea_overhead; } </pre> </div></div> <p>So, without enabling the "ea_inode" feature on MDT, the maximum stripe count is calculated as follows:</p> <div class="preformatted panel" style="border-width: 1px;"><div class="preformattedContent panelContent"> <pre>max_stripes = (sb-&gt;s_blocksize - (sizeof(struct ldiskfs_xattr_header) + sizeof(__u32) + LDISKFS_XATTR_LEN(XATTR_NAME_MAX_LEN)) - sizeof(lmm)) / sizeof(lmm.lmm_objects[0]) = (4096 - (32 + 4 +48) - 48) / 24 = 165 </pre> </div></div> <p>We can close this case.</p> <p>Thanks Mahmoud</p> Development Rank 1|hzze1j: Rank (Obsolete) 9223372036854775807 Severity