I've currently got a single volume consisting of two vdevs, each with two 3TB drives in mirror. I've got about 25% of my usable space free, and at the current rate of increase, I expect to need to add more capacity at around the end of the year, most likely by adding a pair of new drives. I was wondering what people think is the best, simplest or most reliable way to do this. Given that it's some way off, I'm only really looking for general suggestions, so feel free to skimp on the details.
I initially had two disks in mirror (bought in August 2017), so the simplest way to expand was to add two more of the same size in a second vdev (in August 2018). I could add two more 3TB drives in a third vdev, but I'm aware that this is somewhat wasteful of space, so I suspect I'd be better served by a RAID-Z2 containing those six drives. Based on what I've read, there's no way to convert my current setup to a Z2 short of copying all the data off of the current drives, deleting the current four-disk volume and creating a new 6-disk volume in its place. I do have a stack of non-NAS 1TB drives that I could temporarily shunt the data to, so that's an option.
Alternatively I could add a pair of larger drives as a third mirrored vdev in the current volume and postpone any thoughts of converting to RAID-Z2 for a while. As I understand it, there'd be no real point in replacing the existing disks with larger disks in the current vdevs because I'd want to keep using the old disks anyway, so it would be simpler to just expand the existing volume.
What would you more experienced people do in my situation? One of the above options or something different? Thanks in advance.
I initially had two disks in mirror (bought in August 2017), so the simplest way to expand was to add two more of the same size in a second vdev (in August 2018). I could add two more 3TB drives in a third vdev, but I'm aware that this is somewhat wasteful of space, so I suspect I'd be better served by a RAID-Z2 containing those six drives. Based on what I've read, there's no way to convert my current setup to a Z2 short of copying all the data off of the current drives, deleting the current four-disk volume and creating a new 6-disk volume in its place. I do have a stack of non-NAS 1TB drives that I could temporarily shunt the data to, so that's an option.
Alternatively I could add a pair of larger drives as a third mirrored vdev in the current volume and postpone any thoughts of converting to RAID-Z2 for a while. As I understand it, there'd be no real point in replacing the existing disks with larger disks in the current vdevs because I'd want to keep using the old disks anyway, so it would be simpler to just expand the existing volume.
What would you more experienced people do in my situation? One of the above options or something different? Thanks in advance.
