Thanks for confirming this. Best, R. On Mon, 21 May 2012 08:20:49 +0200,Daniel M?ller <mueller at tropenklinik.de> wrote: > I am running a two node gluster in replication mode. From my experience I > can tell you in a samba pdc/bdc environment. If one node is down the other > serves the clients as > if nothing has happened. > Greetings > Daniel > ----------------------------------------------- > EDV Daniel M?ller > Leitung EDV > Tropenklinik Paul-Lechler-Krankenhaus > Paul-Lechler-Str. 24 > 72076 T?bingen > Tel.: 07071/206-463, Fax: 07071/206-499 > eMail: mueller at tropenklinik.de > Internet: www.tropenklinik.de > ----------------------------------------------- > -----Urspr?ngliche Nachricht----- > Von: gluster-users-bounces at gluster.org > [mailto:gluster-users-bounces at gluster.org] Im Auftrag von John Jolet > Gesendet: Montag, 21. Mai 2012 02:47 > An: Ramon Diaz-Uriarte > Cc: <gluster-users at gluster.org>; Brian Candler > Betreff: Re: GlusterFS on a two-node setup > On May 20, 2012, at 4:55 PM, Ramon Diaz-Uriarte wrote: > > > > > > > > On Sun, 20 May 2012 20:38:02 +0100,Brian Candler <B.Candler at pobox.com> > wrote: > >> On Sun, May 20, 2012 at 01:26:51AM +0200, Ramon Diaz-Uriarte wrote: > >>> Questions: > >>> ========== > >>> > >>> 1. Is using GlusterFS an overkill? (I guess the alternative would be > >>> to use NFS from one of the nodes to the other) > > > >> In my opinion, the other main option you should be looking at is DRBD > >> (www.drbd.org). This works at the block level, unlike glusterfs > >> which works at the file level. Using this you can mirror your disk > remotely. > > > > > > Brian, thanks for your reply. > > > > > > I might have to look at DRBD more carefully, but I do not think it > > fits my > > needs: I need both nodes to be working (and thus doing I/O) at the > > same time. These are basically number crunching nodes and data needs > > to be accessible from both nodes (e.g., some jobs will use MPI over > > the CPUs/cores of both nodes ---assuming both nodes are up, of course ;-). > > > > > > > > > >> If you are doing virtualisation then look at Ganeti: this is an > >> environment which combines LVM plus DRBD and allows you to run VMs on > >> either node and live-migrate them from one to the other. > >> http://docs.ganeti.org/ganeti/current/html/ > > > > I am not doing virtualisation. I should have said that explicitly. > > > > > >> If a node fails, you just restart the VMs on the other node and away you > go. > > > >>> 2. I plan on using a dedicated partition from each node as a brick. > >>> Should I use replicated or distributed volumes? > > > >> A distributed volume will only increase the size of storage available > (e.g. > >> combining two 600GB drives into one 1.2GB volume - as long as no > >> single file is too large). If this is all you need, you'd probably > >> be better off buying bigger disks in the first place. > > > >> A replicated volume allows you to have a copy of every file on both > >> nodes simultaneously, kept in sync in real time, and gives you > >> resilience against one of the nodes failing. > > > > > > But from the docs and the mailing list I get the impression that > > replication has severe performance penalties when writing and some > > penalties when reading. And with a two-node setup, it is unclear to me > > that, even with replication, if one node fails, gluster will continue > > to work (i.e., the other node will continue to work). I've not been > > able to find what is the recommended procedure to continue working, > > with replicated volumes, when one of the two nodes fails. So that is > > why I am wondering what would replication really give me in this case. > > > > > replicated volumes have a performance penalty on the client. for instance, > i have a replicated volume, with one replica on each of two nodes. I'm > front ending this with an ubuntu box running samba for cifs sharing. if my > windows client sends 100MB to the cifs server, the cifs server will send > 100MB to each node in the replica set. As for what you have to do to > continue working if a node went down, i have tested this. Not on purpose, > but one of my nodes was accidentally downed. my client saw no difference. > however, running 3.2.x, in order to get the client to use the downed node > after it was brought back up, i had to remount the share on the cifs server. > this is supposedly fixed in 3.3. > It's important to note that self-healing will create files created while the > node was offline, but does not DELETE files deleted while the node was > offline. not sure what the official line is there, but my use is archival, > so it doesn't matter enough to me to run down (if they'd delete files, i > wouldn't need gluster..) > > Best, > > > > R. > > > > > > > > > >> Regards, > > > >> Brian. > > -- > > Ramon Diaz-Uriarte > > Department of Biochemistry, Lab B-25 > > Facultad de Medicina > > Universidad Aut?noma de Madrid > > Arzobispo Morcillo, 4 > > 28029 Madrid > > Spain > > > > Phone: +34-91-497-2412 > > > > Email: rdiaz02 at gmail.com > > ramon.diaz at iib.uam.es > > > > http://ligarto.org/rdiaz > > > > _______________________________________________ > > Gluster-users mailing list > > Gluster-users at gluster.org > > http://gluster.org/cgi-bin/mailman/listinfo/gluster-users > _______________________________________________ > Gluster-users mailing list > Gluster-users at gluster.org > http://gluster.org/cgi-bin/mailman/listinfo/gluster-users -- Ramon Diaz-Uriarte Department of Biochemistry, Lab B-25 Facultad de Medicina Universidad Aut?noma de Madrid Arzobispo Morcillo, 4 28029 Madrid Spain Phone: +34-91-497-2412 Email: rdiaz02 at gmail.com ramon.diaz at iib.uam.es http://ligarto.org/rdiaz
