Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Thank you all, guys! Lars, that's what I was afraid of. Your explanation makes sense, I keep it for future use. Patrick, this cross-replicated architecture is what I was planning first, and obviously I'll keep my plans. :-) Just curious : Does anyone know how folks such as FalconStore and DataCore, who AFAIK claim that they do support fully active/active replication, do implement their stuff ? Or is it just "well-packed" cross-replication just like Patrick talks about ? Thanks to all 3 however! Best regards, Pascal. Nathan Cerny wrote: > > Helps if I send this to the list... > > ---------- Forwarded message ---------- > From: Nathan Cerny <ncerny at gmail.com> > Date: Mon, Apr 4, 2011 at 4:54 PM > Subject: Re: [DRBD-user] DRBD primary/primary vs. VMFS3 ? > To: pberton <pascal.berton3 at free.fr> > > > You have to run Protocol C to do primary/primary. Protocol C ensures both > nodes know of each block write before it's reported as complete. So in > your > instance, one VM would get the block, and another would get a different > block. There is no chance of them both reserving the same block. > > At least that's how I understand Protocol C. I'm sure someone else will > correct me if I'm mistaken! > > > > On Mon, Apr 4, 2011 at 11:33 AM, pberton <pascal.berton3 at free.fr> wrote: > >> >> Hi folks! >> I've read a few posts talking about DRBD vs. VMFS3, but none seem to >> answer >> my question. May be someone can help. Here's the picture : >> I'm thinking of a primary/primary config, with ESXs on both sides. If >> hosted >> VMs do snapshots or make use of thin disks on both sides, corresponding >> files will grow step by step or should I say, block by block, each new >> block >> allocation being securized using SCSI reservations from the host running >> that VM. >> Now, guess 2 VMs on different sides of the replication chain make a new >> block request at the same time. What would happen ? I suppose SCSI >> reservations are not replicated by DRBD, therefore, each host will make >> its >> own reservation and potentially allow the same block to both VMs leading >> to >> corruption ? >> Has anyone already played with this kind of architecture ? Is >> primary/primary definitely a no-no for such architectures or is there >> some >> magic feature that can help me out build something safe ? >> Thanks by advance! >> Best regards, >> Pascal. >> -- >> View this message in context: >> http://old.nabble.com/DRBD-primary-primary-vs.-VMFS3---tp31315179p31315179.html >> Sent from the DRBD - User mailing list archive at Nabble.com. >> >> _______________________________________________ >> drbd-user mailing list >> drbd-user at lists.linbit.com >> http://lists.linbit.com/mailman/listinfo/drbd-user >> > > > > -- > Nathan Cerny > > ------------------------------------------------------------------------------- > "I have always wished that my computer would be as easy to use as my > telephone. My wish has come true. I no longer know how to use my > telephone." > --Bjarne Stroustrup, Danish computer scientist > ------------------------------------------------------------------------------- > > > > > -- > Nathan Cerny > > ------------------------------------------------------------------------------- > "I have always wished that my computer would be as easy to use as my > telephone. My wish has come true. I no longer know how to use my > telephone." > --Bjarne Stroustrup, Danish computer scientist > ------------------------------------------------------------------------------- > > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user > > -- View this message in context: http://old.nabble.com/DRBD-primary-primary-vs.-VMFS3---tp31315179p31354081.html Sent from the DRBD - User mailing list archive at Nabble.com.