Add extra storage to volume

[imetje]

Hello,

I am new to a NAS Synology DS220+ and I can't figure something out. At first I had one Seagate 4TB HDD, but I want to expand my storage with another 4TB (8TB total).
(The backup is done on another external HDD, which means I don't need to replicate the data.)

I have bought another Seagate 4TB HDD, but I can't add this drive as extra storage. The raid-type of the current volume is SHR, which means that it automatically replicate the current HDD to the new HDD. How can I change/revert this to get a volume with 8TB storage? I am not able to change the RAID-type in the storage pool, I do not understand why this is. Do I need to (hard) reset the volume/NAS?

Thanks in advance for helping me!

Ime

 

[EAZ1964]

Create another pool and add the disk to that pool, you then create a 2nd volume. It is called simple or basic volumes 2 times a 4 TB.

some other posts will mention RAID0 or JBOD. These will create a single 8 TB volume. I always advice against them as disk upgrade is not possible and, if one disk fails, you will lose ALL data.
all the above is described in the fine Synology knowledgebase in one of the first chapters about setting up a sytem.

 

[Telos]

If you want one volume comprised of both drives, delete the existing volume (back up first, if you must). Next, add the second drive to the pool, and then, create a JBOD volume with both drives. Know though that a failure of either drive will take out the entire volume, so be sure you take backups of any important files.

 

[Deleted member 673]

@Telos, would you please comment on pros/cons of JBOD vs. RAID0? I'm advising a friend in a similar situation - two drive NAS with suitable backup and no need for redundancy. I had assumed that RAID0 would be the better choice based on read/write performance. What are the advantages of JBOD for a two-drive mashup? Thanks for any further thoughts. Ron

 

[Telos]

JBOD vs. RAID0

For a 2-drive setup, it's nearly a coin toss, and I would concur with your RAID0 choice.

• You can start out with one drive with JBOD, and add a second drive later. With RAID0, you must use two drives initially.
• RAID0 uses striping (vs spanning) so there is a performance advantage. If different size drives are used, striping is limited to the smallest drive size, however you can use the full summed capacity. Exactly how Synology manages this, I'm unsure.

 

[EAZ1964]

I already stated that I never advise RAID0 or JBOD on a NAS. The risk of losing all your data is 4 times higher than basic volumes, so take care for your backups.
But additionally: do not expect the performance improvement to be noticable, as 105MB/s ethernet speed will cap it anyway, so only internal data movements will be somewhat quicker.

 

[Deleted member 673]

The 4-times failure rate for two drives may not be intuitive to some. For a quick review, there's interesting reading in Wikipedia regarding "Correlated Failures" in RAID arrays.

RAID0 or JBOD have a place, IMHO, where #1: availability is not a strong requirement (e.g. home media server); #2: backups are current and redundant; and #3: there's a documented and practiced process to recover from a failure.

For RAID0 or JBOD, I would assume a worst case scenario: that a drive in your primary storage array has just failed; and that there will be a failure again tomorrow. Then decide if RAID0 or JBOD is the best choice. Ron