Just realized something but most likely it's just me missing it. If I were to add additional storage servers to the mix, doesn't it mean I would have to edit the volume files for every single application server and add an entry for datasrv2vol0 then datasrv3vol0 when I add a fourth? Sounds a little tedious and also if I didn't understand wrongly, replicate will simply use these to replicate the same data so I don't get increased capacity, just increased redundancy. On 6/30/10, Emmanuel Noobadmin <centos.admin at gmail.com> wrote: > Thanks for the help! Now that I'm certain I'm not trying something > undoable, I'll probably test drive on VMs first before ordering the > physical machines. But before that, I'll still have to decide between > ESXi/Xen/KVM. > > > > On 6/29/10, Jeff Darcy <jdarcy at redhat.com> wrote: >> On 06/29/2010 10:04 AM, Emmanuel Noobadmin wrote: >>> So most likely I would run two or more physical machines with VM to >>> failover to each other to catch situations of a single machine >>> failure. Along with that a pair of storage server. In the case of a >>> total failure where both the primary & secondary VM dies physically, >>> roll in a new machine to load up the VM images still safe on the >>> gluster data servers. >>> >>> So in this case would I be correct that my configuration, assuming a >>> basic 2 physical VM host server and 2 storage server would probably >>> look something like >>> >>> volume rep0 >>> type cluster/replicate >>> option read-subvolume vmsrv0vol0 >>> subvolumes vmsrv0vol0 datasrv0vol0 datasrv1vol0 >>> end-volume >>> >>> >>> volume rep1 >>> type cluster/replicate >>> option read-subvolume vmsrv1vol0 >>> subvolumes vmsrv1vol0 datasrv0vol0 datasrv1vol0 >>> end-volume >>> >>> volume my_nufa >>> type cluster/nufa >>> option local-volume-name rep0 >>> subvolumes rep0 rep1 >>> end-volume >>> >>> Or did I lose my way somewhere? :) >> >> That looks reasonable to me, except that the last stanza would only >> apply on vmsrv0. For vmsrv1, you'd want this instead: >> >> volume my_nufa >> type cluster/nufa >> option local-volume-name rep1 # this is the only difference >> subvolumes rep0 rep1 >> end-volume >> >> It's a little unfortunate that you can't do this with a single volfile, >> perhaps with $-variable substitutions or some such, but that's the way >> it is AFAIK. >> >> >>> Does it make any sense to replicate across all 3 or should I simply >>> spec the VM servers with tiny drives and put everything on the gluster >>> storage which I suppose would impact performance severely? >> >> That's a pretty murky area. With a fast interconnect it's tempting to >> say the "storage of record" should be only on the data nodes and the app >> nodes should only do caching. It would certainly be simpler, though >> with more than two data nodes you'd have to do essentially the same >> layering of distribute on top of replicate (nufa wouldn't be >> particularly useful in that configuration). If you wanted to stick with >> something more like the above, you'd just need to pair each app node >> with a data node, so e.g. rep0=vmsrv0vol0+datasrv0vol0 and >> rep1=vmsrv1vol0+datasrv1vol1. You would probably also want to "cross" >> the read-subvolume assignments, so for example vol0 would go first to >> datasrv1vol0 instead of vmsrv1vol0 for rep1. This avoids having the app >> nodes talk to each other when they could be talking to data nodes >> instead. >> _______________________________________________ >> Gluster-users mailing list >> Gluster-users at gluster.org >> http://gluster.org/cgi-bin/mailman/listinfo/gluster-users >> >
