<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Apr 24, 2017 at 1:24 PM, Gandalf Corvotempesta <span dir="ltr"><<a href="mailto:gandalf.corvotempesta@gmail.com" target="_blank">gandalf.corvotempesta@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><span class="gmail-"><div><div class="gmail_extra"><div class="gmail_quote">Il 24 apr 2017 9:40 AM, "Ashish Pandey" <<a href="mailto:aspandey@redhat.com" target="_blank">aspandey@redhat.com</a>> ha scritto:<br type="attribution"><blockquote class="gmail-m_-598475389498618417quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:times new roman,new york,times,serif;font-size:12pt;color:rgb(0,0,0)"><div><br></div><div>There is difference between server and bricks which we should understand.<br></div><div>When we say m+n = 6+2, then we are talking about the bricks.<br></div><div>Total number of bricks are m+n = 8. <br></div><div><br></div><div>Now, these bricks could be anywhere on any server. The only thing is that the server should be a part of cluster.<br></div><div>You can have all the 8 bricks on one server or on 8 different servers.<br></div><div>So, there is no *restriction* on number of servers when you add bricks. However, the number of bricks which you want to add should be in multiple of the <br></div><div>configuration you have.<br></div></div></div></blockquote></div></div></div><div dir="auto"><br></div></span><div dir="auto">This is clear but it doesn't change the result</div><div dir="auto">As no one is using gluster to replicate data by loosing redundancy (it's nonsense), adding bricks means adding servers</div><div dir="auto">If our server are already full with no more available slots for adding disks, the only solution is to add 8 servers more (at least 1 brick per server)</div><span class="gmail-"><div dir="auto"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail-m_-598475389498618417quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:times new roman,new york,times,serif;font-size:12pt;color:rgb(0,0,0)"><div></div></div></div></blockquote></div></div></div><div dir="auto"><br></div><div dir="auto"><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail-m_-598475389498618417quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div><div style="font-family:times new roman,new york,times,serif;font-size:12pt;color:rgb(0,0,0)"><div><br></div><div>In you case it should be 8, 16, 24....<br></div><div class="gmail-m_-598475389498618417quoted-text"><div><br></div><div>"can I add a single node moving from 6:2 to 7:2 and so on ?"</div></div><div>You can not make 6+2 config volume to 7+2 volume. You can not change the *configuration* of an existing volume.</div><div>You can just add bricks in multiple to increase the storage capacity.</div></div></div></blockquote></div></div></div><div dir="auto"><br></div></span><div>Yes and this is the worst thing in gluster: the almost zero flexibility <br></div></div></blockquote><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto"><br></div><div dir="auto">Bigger the cluster, higher the cost to maintain it or expand it.</div></div></blockquote><div><br></div><div>At least in case of EC it is with good reason. If you want to change volume's configuration from 6+2->7+2 you have to compute the encoding again and place different data on the resulting 9 bricks. Which has to be done for all files. It is better to just create a new volume with 7+2 and just copy the files on to this volume and remove the original files on volume with 6+2.<br></div><div><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto"><br></div><div dir="auto">If you start with a 6:2 by using commodity hardware, you are screwed, your next upgrade will be 8 servers with 1 disk/brick each.</div></div></blockquote><div><br></div><div>Not true.<br> <br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto"><br></div><div dir="auto">Yes, gluster doesn't make use of any metadata server, but I really prefer to add 2 metadata server and 1 storage server at once when needed than avoid metadata servers but being forced to add a bounch of servers every time</div><div dir="auto"><br></div><div dir="auto">More servers means more power cost, more hardware that could fails and so on.</div><div dir="auto"><br></div><div dir="auto">Let's assume a replica 3 cluster.</div><div dir="auto">If I need to add 2tb more, I have to add 3 servers with 2tb on each server.</div><div dir="auto">Ceph, Lizard, Moose and others allow adding a single server/disk and then they rebalance data aroud by freeing up the used space adding the new disk.</div></div></blockquote><div><br></div><div>Didn't understand this math. If you want to add 2TB capacity to a volume that is 3-way replicated, you essentially need to add 6TB in whatever solution you have. At least 6TB with a single server. Which you can do even with Gluster.<br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto"><br></div><div dir="auto">I thought that this lack of flexibility was addressed is some way in latest version...</div></div></blockquote><div><br></div><div>I think we had this discussion last July[1] with you that we can simulate the same things other storage solutions with metadata do by doing replace-bricks and rebalance. If you have a new server with 8 bricks then we can add a single server and make sure things are rebalanced with 6+2. Please note it is better to use data-bricks that is power of 2 like 4+2/8+2/16+4 etc than 6+2. <br><br></div><div>Are you suggesting this process to be easier through commands, rather than for administrators to figure out how to place the data?<br></div><div><br>[1] <a href="http://lists.gluster.org/pipermail/gluster-users/2016-July/027431.html">http://lists.gluster.org/pipermail/gluster-users/2016-July/027431.html</a><br><br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div dir="auto"></div></div>
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