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Stepan,</div>
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You say OSS here, I think you mean OST - OSS is "object storage server", OST is "object storage target".</div>
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That aside, your note is clear.</div>
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So, 24 OSTs on 6 OSSes, so 4 per. Your setup looks fine - you are likely hitting a bug.</div>
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Here, this is the most recent version - not all the bugs are fixed, but it is worth giving this one a try:</div>
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<a href="https://review.whamcloud.com/c/fs/lustre-release/+/64970" id="OWA115d0bfe-5a77-e513-32f2-d743c9520d93" class="OWAAutoLink">https://review.whamcloud.com/c/fs/lustre-release/+/64970</a></div>
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This includes an EC performance improvement and a number of bug fixes.</div>
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If you still hit that issue, can you please gather debug logs like this on the client:</div>
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lctl set_param *debug=-1 debug_mb=10000</div>
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lctl clear</div>
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lfs mirror resync [file]</div>
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lctl dk > /tmp/log</div>
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Then tar up the log file - it will be too big for the mailing list, but you could put it on google drive?</div>
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Also, how are you taking the nodes down? What did you do to 'lose' them - shut them down, or ...? Just helpful background.</div>
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Thanks!</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> lustre-discuss <lustre-discuss-bounces@lists.lustre.org> on behalf of Stepan Beskrovnyy via lustre-discuss <lustre-discuss@lists.lustre.org><br>
<b>Sent:</b> Wednesday, April 8, 2026 9:18 AM<br>
<b>To:</b> lustre-discuss@lists.lustre.org <lustre-discuss@lists.lustre.org><br>
<b>Subject:</b> [lustre-discuss] Supporting more than 4 parity OST’s</font>
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<div>Hello everyone!
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<div dir="auto">In my diploma project I use WIP EC branch, and I need to have more parity oss’s than current supported. (More than 4, in my case - 8). </div>
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<div dir="auto">I use cluster topology with 24 oss’s laid on 6 servers, 4 oss’s per node each. (Due to performance issues I cant use less, I did a topic about client performance limitation, because of it I try to avoid this by adding oss’s). I want to lose
2 of 6 nodes(requirement from the professor). In this case I need 8 parity oss’s with scheme n+8(16+8 for example) </div>
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<div dir="auto">I found a way to use custom EC layouts with —ec-expert flag and set 16+8 layout. Then I killed 8 random oss’s and mirror resync funtion falls with error “resource temporary unavailable”. </div>
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<div dir="auto">Is there any way to use layouts with more than 4 oss’s and use resync on them? I know, that EC is very WIP branch, but is anyone knows or tested this feature with this layouts yet ? I’m ready to use at my own risk and will fix bugs if I would
see some, but help with the way how to set up 16+8 layout and rebuild file on it. </div>
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<div dir="auto">Thanks, </div>
<div dir="auto">Stepan</div>
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