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<p class="MsoNormal"><span lang="EN-US">We normally suggest to use HW RAID for data storage. This has the advantage<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">that we can replace failed disk without service interruption (node stays online).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">When using sheepdog (or ceph), HW RAID additionally increase redundancy,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">and avoid recovery actions most times.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Unfortunately, this is quite expensive compared to using a single disk (or 2 single
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">disks without raid controller).<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">With such single disk setup, is it possible to replace a damaged disk while the node
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">keeps running (assuming HW supports hotplug)?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">NOTE: If we can’t hotplug disks, any disk failure need a poweroff/reboot. That start<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">auto-recovery and produces massive network traffic.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">If I run 2 sheeps on 2 separate disks (on same node), recovery use the second sheep to
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">copy data (no network traffic involved)? <o:p>
</o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Any experiences on those topic?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">- Dietmar<o:p></o:p></span></p>
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