I recently decided to replace my old Synology NAS, a DS416, with a more powerful version, a DS423+. This turned out to take much longer than expected, mainly because I also wanted to take the opportunity to also start using btrfs as a more robust filesystem, and so needed to migrate my data as well.
For the migration, Synology recommends using their backup solution, Hyper Backup, but their steps are not efficient, if you can live with a service interruption of a few days. Their suggestion is to run a backup of the old system, restore to a new system, stop using the old system, repeat transfer with incremental backup, switch over to the new system, and start service again. That works fine with powerful hardware, and with enough space for all the backups, and it makes sure that all permissions are copied correctly.
This description leads you astray if your old NAS is slow, you lack space, or you can tolerate a longer interruption. With a slow NAS, encryption can become a bottleneck, and a backup of an encrypted folder to an encrypted target over an encrypted connection meant that backup speeds were below 15 MB/s. Instead do the following:
- Move the disks directly to your new NAS. Use Synology Assistant on your computer to verify that you can install DSM without loss.
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Prepare your old NAS for backup duty: put in empty disks, create a redundant storage pool on them to receive your data, add a volume with shared folder, install Hyper Backup Vault. If you needed to grab some SMR disks, trim them with
fstrim
via SSH. -
Backup the data to the old NAS, including all package info. I used Hyper Backup for this, with client-side encryption for the backup so that there is only one encryption step, and it is done by the powerful new NAS. Still I had only around 45 MB/s backup and 40 MB/s restore speeds with my 5400rpm HDDs.
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Delete the volumes on the new NAS, and create btrfs volumes instead. Make a note of the packages that are uninstalled to put them back later. Recreate the shared folders before you run the restore, so that you have control over which folders should have integrity checks enabled.
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Restore the backup to the new NAS.
Since Hyper Backup is quite slow as noted, you might want to use direct copies instead. This can give problems with permissions, and means a slightly higher risk of data loss. On my old NAS, where I wanted to keep encryption, it was even slower at 30 MB/s as doing encryption twice (transfer and rest) slowed it down.