Gandalf Corvotempesta
2016-Aug-09 17:38 UTC
[Gluster-users] Need help to design a data storage
Il 09 ago 2016 19:20, "Ashish Pandey" <aspandey at redhat.com> ha scritto:> 3 - EC with redundancy 2 that is 4+2 > The over all storage space you get is 4TB and any 2 bricks can be down atany point of time. So it is as good as replica 3 but providing more space. Not really. With replica 3 i can set the brick location on different servers so that i can loose multiple servers and not only multiple bricks 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 ......... 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160809/6379121b/attachment.html>
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 ......... ----- Yes, redundant data spread across multiple servers. In my example I mentioned 6 different nodes each with one brick. Point is that for 4+2 you can loose any 2 bricks. It could be because of node failure or brick failure. 1 - 6 bricks on 6 different nodes - any 2 nodes may go down - EC win 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. In this case replica 3 would win. ----- Original Message ----- From: "Gandalf Corvotempesta" <gandalf.corvotempesta at gmail.com> To: "Ashish Pandey" <aspandey at redhat.com> Cc: gluster-users at gluster.org Sent: Tuesday, August 9, 2016 11:08:12 PM Subject: Re: [Gluster-users] Need help to design a data storage Il 09 ago 2016 19:20, "Ashish Pandey" < aspandey at redhat.com > ha scritto:> 3 - EC with redundancy 2 that is 4+2 > 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.Not really. With replica 3 i can set the brick location on different servers so that i can loose multiple servers and not only multiple bricks 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 ......... 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. _______________________________________________ Gluster-users mailing list Gluster-users at gluster.org http://www.gluster.org/mailman/listinfo/gluster-users -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160809/ccbc2a19/attachment.html>