Hi,<div><br></div><div>I have a few questions concerning LVM mirror implementation, and I couldn&#39;t find any suitable design doc</div><div><br></div><div>I need to setup a dual site ( a few miles between the 2 sites, around 1 ms RTD) mirror based cluster system.</div>
<div><br></div><div>-  what is the default behaviour of the mirroring, writing in parallel to both mirror legs or serialized ? what about read requests ?</div><div><br></div><div>- for write requests, is the ack returned to the application (thru VFS) when the 2 legs are updated or only when the first is updated ?</div>
<div>- Is there a way to control it ?</div><div><br></div><div>- what happens if the log device is lost ?</div><div><br></div><div>I saw a post about LVM mirror <span class="Apple-style-span" style="border-collapse: collapse; white-space: pre; -webkit-border-horizontal-spacing: 2px; -webkit-border-vertical-spacing: 2px;">vs mdadm where it is about the location of the mirror log (<span class="Apple-style-span" style="border-collapse: separate; white-space: normal; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; "><a href="https://www.redhat.com/archives/linux-lvm/2009-July/msg00012.html">https://www.redhat.com/archives/linux-lvm/2009-July/msg00012.html</a>) someone gave the answer that when creating the LV&#39;s with --alloc anywhere it will auto locate the log on any of the PV&#39;s.</span></span></div>
<div><br></div><div><span class="Apple-style-span" style="border-collapse: collapse; white-space: pre; -webkit-border-horizontal-spacing: 2px; -webkit-border-vertical-spacing: 2px;"><span class="Apple-style-span" style="border-collapse: separate; white-space: normal; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; ">According to what I could read, the --alloc doesn&#39;t intend for that, am I right ?</span></span></div>
<div><br></div><div><span class="Apple-style-span" style="border-collapse: collapse; white-space: pre; -webkit-border-horizontal-spacing: 2px; -webkit-border-vertical-spacing: 2px;"><span class="Apple-style-span" style="border-collapse: separate; white-space: normal; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; ">Brem ,  </span></span></div>
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