Our layout is something like 80+ VM's going from a 100mbit link at the primary site to a 50mbit link at the DR site. We would be looking at throttling the throughput to about 30mbit during weekdays and letting it run at the full 50mbit afterhours and on weekends. Based on that, I think I am going to be cutting it pretty close, maybe even not getting it to fit at all.
Anyway, I've been playing around with replicas because I really like the "failover" capabilities built in and I like that the machine is essentially ready to be powered on in place. I've also looked at backup jobs because I really like the optimizations such as deduplication within the job and the extras like SureBackup and virtual labs. So basically I am torn. Do I go with replication because it provides essentially a warm site that is ready to be powered on? Or do I go with backups to achieve more flexibility? Or do people have success using a combination?
- Some things I don't like about straight replicas:
- If a disk size changes, it forces a full re-replication because the actual disk structure changed. Backups seem to just handle this. It seems like we do this often enough that taking fresh seed loads will get a little old if we use replicas.
- If we have several "similar" machines being backed up (4 nearly identical RDS servers for example), replication sees no benefit from the fact that the data on each is nearly identical. Backups take that into account and only transfer the unique changes (if I recall correctly).
- Replicas do not seem to be able to utilize the newer technologies like SureBackup, etc for ensuring that the data is truly valid and consistent.
- Some things I don't like about straight backups:
- Can't send a ready to be powered on VM directly to VMFS at the remote site. We can use vPower NFS (at least I think I understand that correctly) to provide near power on ready VM's, but it's just not the same as having the DR host's inventory populated with the VM's and ready to go from VMFS datastores.
- Can't have complex retention policies. It looks like the retention policies are still essentially X number of days. I would really like to see something like X daily, X weekly, X monthly, X yearly, where it rolls up and keeps those historically. That is for another time though...
I really want to get some feedback to discuss what others are using in this type of case. I see a lot of forum posts about people in the same boat as me, they are doing their initial designs, but not many that come back and say this is how we did it and it worked or don't do it this way because... Instead, the existing discussions really seem to blur together the backups with the replicas.
Any help, thoughts, beer, etc would be appreciated!