It seems I solved the problem removing the disks and then adding them, with the commands:<br><br>for sdc<br>remove:<strong><span class="cmdname"><br>echo "1" > /sys/class/scsi_host/host0/device/target</span><em>0:0:1/0:0:1:0</em><span class="cmdname">/delete</span></strong>
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<div class="p"><br>To reregister the disk with the kernel used the command:<strong><span class="cmdname"></span></strong><strong><span class="cmdname"><br>echo "</span><em>0 1 0</em><span class="cmdname">" > /sys/class/scsi_host/host0/scan</span></strong>
</div><br>for sdd<br>
remove:<strong><span class="cmdname"><br>
echo "1" > /sys/class/scsi_host/host0/device/target</span><em>0:0:1/0:0:1:1</em><span class="cmdname">/delete</span></strong>
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<div class="p"><br>
To reregister the disk with the kernel used the command:<strong><span class="cmdname"></span></strong><strong><span class="cmdname"><br>
echo "</span><em>0 1 1</em><span class="cmdname">" > /sys/class/scsi_host/host0/scan</span></strong>
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<br>In general <br>deregister<strong><span class="cmdname"><br>echo "1" > /sys/class/scsi_host/hostH/device/target</span><em>H:B:T/H:B:T:L</em><span class="cmdname">/delete</span></strong>

<div class="p">To reregister the disk with the kernel:<strong><span class="cmdname"><br>echo "</span><em>B T L</em><span class="cmdname">" > /sys/class/scsi_host/hostH/scan<br><br></span></strong> Device name persistence not granted. In my case <br>
sdc --> sdi <br>sdd --> sdd<br><br>All operations were transparent and with no downtime.<br>I also removed other disks and then readded (also during I/O using them) and I have to say that multipath seems very robust.<br>
Thanks to the developers.<br>HIH for others.<br>Still I don't understand why  it was before unable to reinstate the path.<br>Gianluca   <br>
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