DAS to NAS Migration

[CrisR82]

With my data hoarding habits spinning out of control, I find myself needing more storage space, so I'm looking to upgrade my 2-bay DAS to a 4-bay NAS around the upcoming holidays, so I thought I should ask something I'm kind'a concerned about.

 

Currently, I'm running a QNAP-TR002 (https://www.qnap.com/en/product/tr-002) with 2 WD UltraStar DC HC580 (24TB), running them in hardware RAID-1 (using the switches on the back of the DAS).

For the future, I have my eyes on a Ugreen NASync DXP4800 Plus (https://nas-eu.ugreen.com/products/ugreen-nasync-dxp4800-plus-nas-storage).

 

The idea is to load up all 4 bays with drives and run them in RAID-5, but due to HDD prices, so my question is - is it possible to take my current 2 24TB drives in RAID-1, put them in the Ugreen NAS and convert them to RAID-5 (after adding another 2 24TB drives) without having to move all the data out of them / erase both drives first?

And as a bonus question - should be sourcing specifically another pair of WD UltraStar DC HC580 or I can mix-and-match vendors and models? I was actually interested in acquiring 2 26TB drives instead, but I heard RAID'ing the drives would essentially make the extra 2TB unusable.

 

P.S. This is my primary data storage, the truly important data is backed up across several different storage mediums and several different countries, the reason I'm doing a RAID-1 right now is because while the data is not critical, re-acquiring it would be a huge time-waste.

[Needfuldoer]

4 minutes ago, CrisR82 said:

is it possible to take my current 2 24TB drives in RAID-1, put them in the Ugreen NAS and convert them to RAID-5 (after adding another 2 24TB drives) without having to move all the data out of them / erase both drives first?

Unfortunately, it doesn't work that way. Creating a RAID array destroys the data on the drives. You might be able to import that mirror into the UGREEN then add a second one to make a RAID 10, or at least two mirrored pools, but personally I don't trust the "RAID" that external enclosures make.

 

The safest thing to do is lifeboat your data to a drive that won't become part of the array, build your 4-drive RAID5, then copy everything back to it. That's what I did when I upgraded from a Synology to the first incarnation of my server. (It went from Synology Hybrid RAID to a ZFS pool with more drives, so I had no choice but to destroy the SHR array. But now that it's ZFS, that pool can be imported into anything that supports ZFS.)

 

12 minutes ago, CrisR82 said:

should be sourcing specifically another pair of WD UltraStar DC HC580 or I can mix-and-match vendors and models? I was actually interested in acquiring 2 26TB drives instead, but I heard RAID'ing the drives would essentially make the extra 2TB unusable.

Match capacities, because RAID will only fill each drive to the capacity of the smallest drive in the array. (Otherwise there's no place to write the parity data for that extra space.) 

 

"RAID"-ish solutions like Synology Hybrid RAID and Unraid can make use of all the space on every drive, with the caveat that they dedicate the largest capacity drive in the array to only parity data.

[CrisR82]

11 minutes ago, Needfuldoer said:

Unfortunately, it doesn't work that way. Creating a RAID array destroys the data on the drives. You might be able to import that mirror into the UGREEN then add a second one to make a RAID 10, or at least two mirrored pools, but personally I don't trust the "RAID" that external enclosures make.

 

The safest thing to do is lifeboat your data to a drive that won't become part of the array, build your 4-drive RAID5, then copy everything back to it. That's what I did when I upgraded from a Synology to the first incarnation of my server. (It went from Synology Hybrid RAID to a ZFS pool with more drives, so I had no choice but to destroy the SHR array. But now that it's ZFS, that pool can be imported into anything that supports ZFS.)

 

Match capacities, because RAID will only fill each drive to the capacity of the smallest drive in the array. (Otherwise there's no place to write the parity data for that extra space.) 

 

"RAID"-ish solutions like Synology Hybrid RAID and Unraid can make use of all the space on every drive, with the caveat that they dedicate the largest capacity drive in the array to only parity data.

Had a feeling it might be like that...well, guess I'll drag out the upgrade a bit into 2026 and just grab x4 26TB drives and keep this DAS as a backup as it is.

[Needfuldoer]

7 minutes ago, CrisR82 said:

Had a feeling it might be like that...well, guess I'll drag out the upgrade a bit into 2026 and just grab x4 26TB drives and keep this DAS as a backup as it is.

Or get one 26 TB drive to use as your lifeboat, and buy the NAS and two more 24 TB drives.

 

Honestly, I think you'd be better off running RAID 10 with drives that size. If you lose one drive in a RAID5 array, you're essentially running without a net because the rest of your drives become a RAID 0 until the array resilvers. (My server has a dozen 12 TB drives in a RAIDz3, so there are three parity drives, plus I have two cold spares.)

[CrisR82]

20 minutes ago, Needfuldoer said:

Or get one 26 TB drive to use as your lifeboat, and buy the NAS and two more 24 TB drives.

 

Honestly, I think you'd be better off running RAID 10 with drives that size. If you lose one drive in a RAID5 array, you're essentially running without a net because the rest of your drives become a RAID 0 until the array resilvers. (My server has a dozen 12 TB drives in a RAIDz3, so there are three parity drives, plus I have two cold spares.)

I actually wasn't familiar with RAID-10 before (as a consequence of never imagining I would one day be able to even consider buying more than 2 high-capacity drives), just looked up the info and I actually might go with that, from what I can gather it's a safer bet than RAID-5 long-term. Thanks for the info!

[porina]

45 minutes ago, CrisR82 said:

The idea is to load up all 4 bays with drives and run them in RAID-5, but due to HDD prices, so my question is - is it possible to take my current 2 24TB drives in RAID-1, put them in the Ugreen NAS and convert them to RAID-5 (after adding another 2 24TB drives) without having to move all the data out of them / erase both drives first?

I'm not familiar with what Ugreen does. Is it its own OS? Assuming it supports RaidZ features, I'm thinking the easiest way for you to convert minimal data moving would be to split the mirror and keep one disk as the sole copy. Wipe the other disk, and add it with the two new ones into 3 disk raidZ1. Move the data off the remaining copy into the raid. Wipe the now empty disk, and use that to expand raid Z1 to 4 disks. This is not perfect, and obviously comes with some risk as you will be at one copy with no redundancy while you execute it. There are some operational considerations with expanding raidZ so read up on that too.

 

37 minutes ago, Needfuldoer said:

"RAID"-ish solutions like Synology Hybrid RAID and Unraid can make use of all the space on every drive, with the caveat that they dedicate the largest capacity drive in the array to only parity data.

Expansion flexibility is why I went with Unraid myself. It has its own set of positives and negatives:

+ you can use mismatched capacity drives

+ in the event more drives fail at the same time than you can recover from, the data on surviving drives is still usable

+ you can add capacity at any time without affecting existing data or protection

- paid software

- sequential read speed is that of a single disk

- sequential write speed in default mode is about half that of a single disk, due to read-write needed for parity calculation, but it only needs the written disk and parity disk(s) spun up. Others can remain sleeping.

- sequential write speed in turbo mode is about that of a single disk, but all disks need to be spinning

* you can optionally add a write cache, but more disks especially if you want that to be redundant also

* parity drive should be equal or bigger than the largest data drive. It can be smaller, but then you cap the usage of your data drives

* you can import disks into the array of more filesystems now, they even added NTFS support recently.

* if the disks in the array are of different performance, operations that use multiple disks will work at the slowest

 

So if you go with Unraid, you could potentially import one of the existing mirror as a data drive assuming it is of a supported format. Add the new drives. Assign one as a parity disk, with other(s) as data disks. Keep the other disk from the mirror as a backup for now. When you start the array, it will build parity and wipe the empty disks. Once that is done you have one disk redundancy, then you can wipe and add the backup drive as another empty data drive.