<html><body><div style="font-family: garamond,new york,times,serif; font-size: 12pt; color: #000000"><div><br></div><div><br></div><hr id="zwchr"><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>From: </b>"Lindsay Mathieson" <lindsay.mathieson@gmail.com><br><b>To: </b>"gluster-users" <gluster-users@gluster.org><br><b>Sent: </b>Monday, October 12, 2015 6:04:01 PM<br><b>Subject: </b>[Gluster-users] Replica 3 cluster, file being healed on all 3 nodes<br><div><br></div><div dir="ltr"><div><div>Have been testing failure mode by killing the gluster processes on a node (killall glusterd glusterfsd). <br><div><br></div>Pleasantly surprised how much smoother gluster has got at this since 3.5, heal takes a while but it no longer kills cluster performance. Probably helps that I'm using replica 3 now rather than replica 2.<br><div><br></div></div>However I managed to create a state where a file was being healed on all three nodes (probably y live migrating a VM while it was being healed). I didn't think that was possible without creating a split brain problem, but it eventually got all the way to being healed.<br></div></div></blockquote><div>I don't think it is possible for heal of this image to be happening on all three nodes.<br></div><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><div dir="ltr"><div><br></div>Is this the diff algorithm in play? is it comparing blocks on all three nodes using the ones that are identical across two or three nodes? If it encountered a block that was different on all three ndes would that result in split brain?<br></div></blockquote><div>Yes, diff heal performs rolling checksum of every block at same offset on all three copies of the file to see if that block needs heal.<br></div><div><br></div><div>As far as split-brain is concerned, self-heal daemon would not even attempt to heal the file if it detects that the file is in split-brain (due to the absence of at least one good copy).<br></div><div>It is possible for the three copies of the file to have different checksums (when client quorum is disabled) but one of them MUST be a good copy for heal to happen.<br></div><div><br></div><div>-Krutika<br></div><blockquote style="border-left:2px solid #1010FF;margin-left:5px;padding-left:5px;color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><div dir="ltr"><div><div><div><br clear="all"><br>-- <br><div class="gmail_signature">Lindsay</div></div></div></div></div><br>_______________________________________________<br>Gluster-users mailing list<br>Gluster-users@gluster.org<br>http://www.gluster.org/mailman/listinfo/gluster-users</blockquote><div><br></div></div></body></html>