About to replace\upgrade the drives, delete data first?

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About to replace\upgrade the drives, delete data first?

5
1
NAS
DS918+
Hi,
I have a DS918+ with 4 x 6TB drives that are all about 6 years old, in a SHR array with 1-drive tolerance. I have ~16TB of space of which 12TB is used. I recently bought 4 x16TB drives to replace them. My plan is to replace one drive at a time and allow the system to rebuild the array each time until all 4 have been replaced and the new array is completely re-sized to take advantage of the extra space. My biggest concern is that at some point during the 4 rebuilds, one of the old drives may fail and I'll lose everything. I do have everything backed up to local USB drives through HyperBackup, but I really dont want to have to re-create everything and do a restore that could take days. What I was thinking is; one of the folders contains several very large database files that I have completely backed up to a USB drive. If I delete those files from the storage prior to replacing the drives, there will be about 80% less data to rebuild, which should reduce the rebuild time and stress on the existing drives. I could then restore the files from backup and only the new drives would be affected. Does this make any sense technically? Am I missing something that renders this plan invalid? Also, what kind of restore time would I be looking at for ~10TB of data from a USB 3.0 drive through Hyper-backup?

Any responses are appreciated.
Thanks!
 
Hi,
I have a DS918+ with 4 x 6TB drives that are all about 6 years old, in a SHR array with 1-drive tolerance. I have ~16TB of space of which 12TB is used. I recently bought 4 x16TB drives to replace them. My plan is to replace one drive at a time and allow the system to rebuild the array each time until all 4 have been replaced and the new array is completely re-sized to take advantage of the extra space. My biggest concern is that at some point during the 4 rebuilds, one of the old drives may fail and I'll lose everything. I do have everything backed up to local USB drives through HyperBackup, but I really dont want to have to re-create everything and do a restore that could take days. What I was thinking is; one of the folders contains several very large database files that I have completely backed up to a USB drive. If I delete those files from the storage prior to replacing the drives, there will be about 80% less data to rebuild, which should reduce the rebuild time and stress on the existing drives. I could then restore the files from backup and only the new drives would be affected. Does this make any sense technically? Am I missing something that renders this plan invalid? Also, what kind of restore time would I be looking at for ~10TB of data from a USB 3.0 drive through Hyper-backup?

Any responses are appreciated.
Thanks!
If you replace a 6TB drive with a larger one, the system will create a 6TB partition on the new drive and use that to “recover” the missing drive. The unused space on the new drive will initially be “unused space”. This will be repeated as you replace the other drives. Once all the drives have been replaced you can expand the volume to use all the available space. I don’t think there is any performance hit to having multiple partitions on each drive, just something to be aware of.
 
Thanks for the response, I wont panic now when I see it initially not using the new space on the bigger drives. Any thoughts on deleting a large amount of data before the rebuild?
 
Thanks for the response, I wont panic now when I see it initially not using the new space on the bigger drives. Any thoughts on deleting a large amount of data before the rebuild?
I’m not 100% certain, but I think it will make little difference as the rebuild will do a sector by sector copy if the data on the three old drives on to the new one, whether it is empty space or actual data will not make any difference. Others may have tried it and experienced otherwise.
 
Once all the drives have been replaced you can expand the volume to use all the available space.
This is incorrect. After the second drive has been assimilated, the available volume will be increased. And so on after each successive drive.
Any thoughts on deleting a large amount of data before the rebuild?
If the data is unnecessary, delete it up front. But, if you intend to add it back following the drive replacements, just leave it alone, and let the NAS do its thing.
My biggest concern is that at some point during the 4 rebuilds, one of the old drives may fail and I'll lose everything. I do have everything backed up to local USB drives
You have your contingency plan. So no worries.

The only other option you have is to start fresh with the 16 TB drives; then restore... which you are hoping to avoid.

Swap drives and be patient. You will still have full NAS access during rebuilds.
 
Thanks for the responses and the clarification. I'll just leave everything as-is and hope the rebuild(s) go well. This NAS is my home DNS (Pi-Hole on Docker) server as well as several other hats, hopefully it wont go south and I can just rebuild.

Cheers.
 
This is incorrect. After the second drive has been assimilated, the available volume will be increased. And so on after each successive drive.
The volume expansion wasn't automatic when I upgraded 2TB and 3TB drives in my DS1019+ (running DSM 6) a few years back to 4TB drives, I had to expand the volume from the settings. Maybe that has changed since then or in DSM 7.
 
So after 3 disk replacements, I'm down to the last drive. I have tons of space with 3 x 16TB and 1 x 6TB, but I still have one drive to go. What I'm wondering is, when I pull the last 6TB drive, can I just put the last 16TB drive in as a Hot Spare? My volume is currently a 4-disk SHR array with one-drive tolerance, so I'd be changing that to a 3-disk SHR with a hot spare.
 
No, you can't pull an SHR member drive out of a RAID set - you would need to back up, delete the SHR volume and create a new three drive SHR volume, then restore the data.

Also there is no value in having a hot spare on a three drive SHR pool, you would be better off keeping to a four drive pool (better performance). Hot spares don't really make sense in NAS units with such a low number of drive bays.
 

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