<html><body><div style="font-family: times new roman, new york, times, serif; font-size: 12pt; color: #000000"><div>What about EC? Are redundant data spread across multiple servers? If not, multiple replica would be placed on the same server. I can loose 2 bricks (2 disks) but what if I'll loose the whole server with both bricks on it? And when a server fails, multiple bricks are affected .........</div><div><br></div><div>-----<br></div><div><br></div><div>Yes, redundant data spread across multiple servers. In my example I mentioned 6 different nodes each with one brick.<br></div><div>Point is that for 4+2 you can loose any 2 bricks. It could be because of node failure or brick failure.</div><div>1 - 6 bricks on 6 different nodes - any 2 nodes may go down - EC win <br></div><div><br></div><div>However if you have only 2 nodes and 3 bricks on each nodes, then yes in this case even if one node goes down, ec will fail because that will cause 3 bricks down.</div><div>In this case replica 3 would win.<br></div><div><br></div><div><br></div><hr id="zwchr"><div style="color:#000;font-weight:normal;font-style:normal;text-decoration:none;font-family:Helvetica,Arial,sans-serif;font-size:12pt;"><b>From: </b>"Gandalf Corvotempesta" <gandalf.corvotempesta@gmail.com><br><b>To: </b>"Ashish Pandey" <aspandey@redhat.com><br><b>Cc: </b>gluster-users@gluster.org<br><b>Sent: </b>Tuesday, August 9, 2016 11:08:12 PM<br><b>Subject: </b>Re: [Gluster-users] Need help to design a data storage<br><div><br></div><p dir="ltr">Il 09 ago 2016 19:20, "Ashish Pandey" <<a href="mailto:aspandey@redhat.com" target="_blank">aspandey@redhat.com</a>> ha scritto:<br>
> 3 - EC with redundancy 2 that is 4+2<br>
> The over all storage space you get is 4TB and any 2 bricks can be down at any point of time. So it is as good as replica 3 but providing more space.</p>
<p dir="ltr">Not really.<br>
With replica 3 i can set the brick location on different servers so that i can loose multiple servers and not only multiple bricks</p>
<p dir="ltr">What about EC? Are redundant data spread across multiple servers? If not, multiple replica would be placed on the same server. I can loose 2 bricks (2 disks) but what if I'll loose the whole server with both bricks on it? And when a server fails, multiple bricks are affected .........</p>
<p dir="ltr">replica 3 is like a raid10 with 3 disks in each mirror (3 failed bricks in the same replica set=data loss). EC is like raid6 (3 failed bricks in the whole cluster=data loss). The first is safer than the latter but has a huge waste of space.</p>
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