Transforming Full backup (Backup Copy Job) is taking 3 days

[andreash]

I thought I'd give some feedback on my findings with using our Synology rs10613xs+ as backup target.

Based on Toms and Lucas suggestions I tried to change the chunk/stripe size from the default 64KB to 512KB on command line on some spare disks. This is not supported by Synology!
I had to shrink the raid first to get it to a multiple of 512KB and then ran the conversion via mdadm. This should take ~5 days on a three 4TB disk raid 5!

Unfortunately the device crashed for a different reason after one day. On reboot the raid I was trying to resize was completely gone, no configuration remained of it! I guess the Synology tracks the raid configuration in it's database and dropped the raid when it detected the mismatch I created on the commandline.

Shrinking the existing raid array is not an option, and changing the chunk size proved to be a risk to the array itself, so I have stopped my tests at that stage.

I will put in an enhancement request to Synology, but right now they seem to mainly target the SOHO market.

Thanks for all your help!
Andreas