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<b>Scheduled Maintenance Announcement</b></div>
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Dear Users,</div>
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This is a reminder of upcoming scheduled maintenance for the Farm cluster, which will take place on November 19th beginning at 8am. During this time, we will be performing several important updates.</div>
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<b>Notable Activities:</b></div>
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<div><b>Read-Only Cache</b>: We will be <u>reserving the cluster</u> to transition to a read-only cache, which will result in temporary a halt to access.</div>
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<div><b>Brief Network Outages</b>: There will be brief network outages as we transition to new row switches. These outages are expected to be minimal and performed while cluster is reserved.</div>
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<b>What to Expect:</b></div>
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During the maintenance window, access to certain features or services (including JupyterHub) may be temporarily limited or unavailable.</li><li style="font-family: Aptos, Aptos_EmbeddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<div>You may experience brief connectivity disruptions due to the network outages.</div>
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We recommend completing any critical tasks before the maintenance period to avoid any inconvenience.</li></ul>
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<b>Read-Only Cache:</b></div>
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In addition to the information provided in the attached announcement, <b><i>swif2</i></b> was updated to include a new
<i>output</i> feature. This requested feature better handles output files determined at runtime. Please see details here:
<a href="https://scicomp.jlab.org/cli/output.html" id="LPlnk903458" class="OWAAutoLink" title="https://scicomp.jlab.org/cli/output.html">
swif2 output</a>.</div>
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We apologize for any disruptions this may cause and appreciate your understanding. Should you have any questions or need assistance, please feel free to contact our support team at
<a href="mailto:helpdesk@jlab.org" id="LPlnk674532" class="OWAAutoLink" title="mailto:helpdesk@jlab.org">
helpdesk@jlab.org</a>.</div>
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Thank you for your patience.</div>
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Sincerely,</div>
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JLab Scientific Computing Team</div>
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<div id="divRplyFwdMsg" dir="ltr" style="color: inherit;"><span style="font-family: Calibri, sans-serif; font-size: 11pt; color: rgb(0, 0, 0);"><b>From:</b> Wesley Moore<br>
<b>Sent:</b> Monday, October 28, 2024 4:02 PM<br>
<b>To:</b> Laura Hild via Jlab-scicomp-briefs <jlab-scicomp-briefs@jlab.org><br>
<b>Subject:</b> Nov 19: Transition of the Farm /cache filesystem to read-only from farm and ifarm</span>
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<b>Transition of the Farm /cache filesystem to read-only from farm and ifarm</b> </div>
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<b>What is changing?</b> </div>
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On November 19, 2024, during monthly maintenance, the /cache filesystem will be changed to read-only access from farm, ifarm, Globus, and XRootD Data Transfer Nodes. After that date, files will only be copied to /cache via in the following ways: </div>
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The jcache command, which reads files from tape and writes them into /cache </div>
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The jput command, which writes files to tape and can optionally place a copy immediately in /cache when the<i> -cache</i> flag is specified </div>
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Data ingest from the experimental halls using the jmirror command with a regular expression pattern match for data retention in cache. </div>
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<b>Why is this happening?</b> </div>
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The new system will ensure that files move to tape promptly and that /cache is an accurate subset of files stored on tape. </div>
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In the current /cache filesystem, there are a commonly cases where files are in conflict with tape storage, leading to work slow downs. </div>
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Small file handling has been a historic problem, and many small files in /cache were not stored on tape or backed up in any way </div>
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<b>How will this affect farm job workflows?</b> </div>
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Jobs that are part of a SWIF workflow with an output specification to /cache will continue to work. </div>
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Jobs that attempt to write directly to cache using open(), cp, mv, or other POSIX tools will fail. Output from slurm jobs that are not part a SWIF workflow should be stored on /volatile and will need to be moved to tape manually using jput on ifarm. Generally,
slurm workflows that need to interact with tape would be better implemented using SWIF. </div>
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Note that jput is not available on (non-interactive) farm nodes because it may queue, stalling the farm node and potentially timing out the job. </div>
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<b>What is not changing?</b> </div>
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Cache deletion policy: remains unchanged. </div>
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Cache file pinning: continues to work as before. </div>
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jcache client: continues to work as before.</div>
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SWIF outputs to /cache: continues to work as before.</li></ul>
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References: </div>
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KBA: <u><a href="https://jlab.servicenowservices.com/scicomp?id=kb_article_view&sysparm_article=KB0015468" id="OWAb56570e0-cfb1-a88f-add6-a5cdf805a9e2" class="x_OWAAutoLink" title="https://jlab.servicenowservices.com/scicomp?id=kb_article_view&sysparm_article=KB0015468" data-auth="NotApplicable">Migration
to read-only cache</a></u> </div>
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KBA: <span style="color: rgb(5, 99, 193);"><u><a href="https://jlab.servicenowservices.com/scicomp?id=kb_article_view&sysparm_article=KB0014686" id="OWAbd679924-2155-9231-452b-306cd2226db9" class="x_Hyperlink x_SCXW7131722 x_BCX0 x_OWAAutoLink" data-auth="NotApplicable" style="color: rgb(5, 99, 193); margin: 0px;">Computing
Coordinators</a></u></span> </div>
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