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I'd like to start with a 3TB disk I have and add a second 3TB disk later (couple of months). I should end up with 1 6TB volume (no redundancy - I backup elsewhere anything important).

  • What are the correct RAID modes and what are their pros/cons?
  • Can I set it up once and then just add the second disk with no data loss?

If data loss is unavoidable when expanding to the second disk then it's annoying, but not a real problem (I'll move everything out, reformat and copy everything back, it will take ages).

Thanks!

MySidesTheyAreGone
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  • [Synology Knowledgebase - Choose a RAID type](https://www.synology.com/en-us/knowledgebase/DSM/help/DSM/StorageManager/volume_diskgroup_what_is_raid). –  Jul 17 '17 at 20:31
  • What did Synology support say? – EEAA Jul 17 '17 at 23:35

1 Answers1

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A RAID is not a backup. A RAID provides disk redundancy.

If you don't want redundancy (I highly recommend redundancy and don't understand why anyone wouldn't implement disk redundancy) then you don't use a RAID.

For the DS216j, the only "correct" RAID mode would be a RAID 1 (mirrored disks), or a RAID 0 (no redundancy) since the 216j only has 2 hard drive bays. Synology has a good chart outlining the different types of RAIDs here.

When you setup your Synology with the 1 disk, it will be impossible to setup any sort of RAID anyway, because you'll only have 1 disk.

Regarding your second question, yes, you can expand your volume at a later date when you add the 2nd hard drive. Just choose RAID 0. But again, I would strongly encourage you to reconsider, and go with a RAID 1.

David W
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  • Thanks for the chart, do you know about JBOD too? First time I hear about it, seems like it supports any number of drives, even just one. I can't figure out if it would allow me to add a disk without copying everything out and then back in, if it doesn't then RAID 0 seems preferable. – MySidesTheyAreGone Jul 17 '17 at 22:25
  • I highly recommend to go with RAID 1 if you care about your data. The difference between JBOD and RAID-0 : If one disk fails in RAID-0 you lost all your data since its striped over 2 disks. If one disk fails in JBOD you just loose the files on that one disk and the data on the other disk is ok. – Alexios Pappas Jul 18 '17 at 00:32
  • Thanks for the JBOD explanation! I will think about sacrificing half the space for redundancy, it's a high cost to pay for non-important data. The important one is also backed up elsewhere. – MySidesTheyAreGone Jul 18 '17 at 05:47