Backup target SANs

izzion

So, right now, I'm fighting with a pair of Synology DS1515+ units that don't want to actually perform CBT synchronization for our backup data. Hoping someone else has something they would recommend to give me an idea of what to beg for in future budget requests...

Environment:

Backup is being performed by Veeam Backup & Recovery (Enterprise Plus), machines being backed up are Hyper-V VMs. Currently the backup target repository is being mounted via iSCSI on the Windows (physical machine) that is the Veeam host, but I'm not opposed to changing that if necessary and supported.
Backup is split into a group of servers that don't need VSS aware backups (4-5TB of data, 50-100GB of daily changes) and a group that does need VSS aware backups (~1TB of data, 30-60GB of daily changes including hourly transaction log backups). Both jobs are performing a Reverse Incremental within Veeam, I would prefer not to change that.
Offsite backup copy on the non-VSS is being handled by a Veeam Backup Copy job without problems.
For the VSS job, Veeam does not support including the transaction log backups in Backup Copy jobs - the Veeam job will only transfer the most recent daily restore point. Their recommended / supported configuration for getting the transaction log backups replicated offsite is to perform a LUN-level copy with the NAS.

Problem statement:

The Synology NAS is supposed to "just work" with LUN-level CBT & differential copy, but doesn't. I have the LUN a little overprovisioned (3TB on the LUN, versus about 1.4TB in use including the change files), but even cutting the sync time down from 6 days to 3 won't get the shuttle off the field. Synology support can't point out anything wrong that's causing the problem with certainty.

Does anyone have a SAN solution they would recommend that does reliable and performant compression / deduplication / differential backup to an offsite target? Cost is obviously a concern, but actually working matters more.