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On Nov 3, 2025, at 18:58, Oleg Drokin via lustre-devel <lustre-devel@lists.lustre.org> wrote:<br>
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Mon, 2025-11-03 at 16:33 -0800, Jinshan Xiong wrote:</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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I guess users won't have 1PB OSTs, will they?<br>
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probably are already? NASA has a known 0.5P OST configuration:</span><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
<a href="https://www.nas.nasa.gov/hecc/support/kb/lustre-progressive-file-layout-(pfl)-with-ssd-and-hdd-pools_680.html#:~:text=The%20available%20SSD%20space%20in%20each%20filesystem,decimal%20(far%20right)%20labels%20of%20each%20OST" style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;">https://www.nas.nasa.gov/hecc/support/kb/lustre-progressive-file-layout-(pfl)-with-ssd-and-hdd-pools_680.html#:~:text=The%20available%20SSD%20space%20in%20each%20filesystem,decimal%20(far%20right)%20labels%20of%20each%20OST</a><br style="caret-color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">
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In order to maximize rebuild performance for declustered parity RAID,
<div>there are OSTs in production with 90x20TB HDDs = 1.4 PB today,</div>
<div>and requests to have even larger OSTs. We've done a bunch of work</div>
<div>to improve huge ldiskfs OST performance, including the hybrid OST</div>
<div>patches like <a href="https://review.whamcloud.com/51625">https://review.whamcloud.com/51625</a> ("LU-16750 ldiskfs:</div>
<div>optimize metadata allocation for hybrid LUNs"), but there could still</div>
<div>be further improvements in supporting such large OSTs.<br>
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<div>Cheers, Andreas</div>
<div>—</div>
<div>Andreas Dilger</div>
<div>Lustre Principal Architect</div>
<div>Whamcloud/DDN</div>
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