Question Creating a RAID 10 array on ubuntu server from disks containing data

[hotsaucebg4]

Hello. I have remote server running Ubuntu with two 4TB drives that are being used in non-raid way for video storage/hosting.
Can I add two more 4TB disks and create a RAID 10 array (on Software RAID) from the all 4 disks without losing the data that is already written on the first two? Or does the new array need formatting or something?
Backuping the data is inconvenient since the remote server is in datacenter
main goal is to double the read speed since hdds hit 100% sometimes

any help would be appreciated

 

[USAFRet]

Hello. I have remote server running Ubuntu with two 4TB drives that are being used in non-raid way for video storage/hosting.
Can I add two more 4TB disks and create a RAID 10 array (on Software RAID) from the all 4 disks without losing the data that is already written on the first two? Or does the new array need formatting or something?
Backuping the data is inconvenient since the remote server is in datacenter
main goal is to double the read speed since hdds hit 100% sometimes now

No you cannot.

Instantiating the RAID will require full reformatting of whatever drives will be in it.
Loss of all data.


But, this speaks to a deeper, more serious problem.
Do you not have a known good backup of all data on this server?

If not, you are flirting with disaster.

"inconvenient " is a cop out.

 

[hotsaucebg4]

gotcha, thanks for the quick reply. I guess I would find another two disks and send them over for them to make me a backup and then re-populate the array. Downside is that server has only 6 hdd slots, and one slot is used with the 120gig ssd containing the OS, so no more than 4-disk raid10 would fit in that system, or am I wrong?..

 

[LinuxDevice]

This is only speculation, and is probably risky (I've never tried it), but if two new drives were turned into RAID 0 (just striping), then the original disks could be copied to this. Following that, the original disks could be formatted as RAID 0, losing the original disks. I don't know if it is possible, but perhaps there is some way to keep the data on the new RAID 0 and mark it as a RAID 1,0 in degraded mode. Following this, the original disks might be added in while it runs such that it re-syncs and uses all 4 disks. I don't really know if it is possible, but the above essentially treats RAID 0 as a degraded mode RAID 1+0. I don't have disks to try, but it is an interesting question. Anyone know if RAID 0 can be migrated to RAID 1+0?

 

[USAFRet]

This is only speculation, and is probably risky (I've never tried it), but if two new drives were turned into RAID 0 (just striping), then the original disks could be copied to this. Following that, the original disks could be formatted as RAID 0, losing the original disks. I don't know if it is possible, but perhaps there is some way to keep the data on the new RAID 0 and mark it as a RAID 1,0 in degraded mode. Following this, the original disks might be added in while it runs such that it re-syncs and uses all 4 disks. I don't really know if it is possible, but the above essentially treats RAID 0 as a degraded mode RAID 1+0. I don't have disks to try, but it is an interesting question. Anyone know if RAID 0 can be migrated to RAID 1+0?

And even if there were documented, published, tested procedures to do this...I would not do it with the only copy of my data.

 

[LinuxDevice]

And even if there were documented, published, tested procedures to do this...I would not do it with the only copy of my data.

Yeah, I would definitely cringe at this if I needed the data. One possibility though is to at least partially test: If one can create the RAID 0 stripe, copy data into it, and then convert it to RAID 1+0 (but degraded mode) without losing the data (degraded mode should still validate), then you at least know that in theory a sync will succeed. There is the safety of not needing to delete the original disk content without knowing the system sees the RAID 1+0 degraded mode first. It is a bad idea to experiment with using needed data, but maybe in a pinch it makes things possible.