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I am creating a LUN. So far, I have connected the LUN to the computer. If I am right, now I need to initialize the LUN and format it. The NAS I have, has two disks, one I can put data on and one for back-up. The LUN is only a small part of the first disk, which already contains much data.
Now is my question:
Can initialize and format the LUN without the risk loosing all data on the disk?
If I understand you cerrectly, I can make a LUN an initialize it without loosing the data on the disk. Afterwards, I need to format the LUN. Can I do this without the risk loosing the data?
A LUN is a virtual disk. It's just a 25 GB file as far as the RAID array is concerned.
You format the LUN on the PC (or whatever the iSCSI client machine is). That formats the virtual disk (e.g., writes to the 25 GB file), but doesn't affect anything else. The data on the NAS won't be touched.
The NAS I have, has two disks, one I can put data on and one for back-up.
Are you saying that you have two JBOD volumes on the ReadyNAS?
Or are you running XRAID (RAID-1)? You can confirm XRAID by looking on the volume tab in the web ui. If you see a green stripe on the XRAID button then you are running XRAID.
Ok, so you are running RAID-1, with the disks mirrored. Mirrored disks isn't the same as backup btw. How much free space do you have in the array?
Normally you just initialize the LUN, and the LUN container file takes space on the RAID array (like any other file). A thick LUN will take the full allocated size right away. A thin LUN can be overallocated - it will grow as you put more files on it. The thick version generally works out better, but if don't have enough space you could make a thin one.
You could of course expand the array (buying two larger disks), and then create a thick LUN. If your NAS is running out of space, then that's the best solution (though of course it isn't free). A variant here is to upgrade to a NAS with more bays (say an RN214), migrate your current disks, and add one disk to it. That is more expensive, but would give you more expansion options later.
The other way to increase capacity is to create two jbod volumes. This is destructive, you will lose the data you currently have on the NAS. You'd do this by
back up all your files
uninstall your apps
switch to flexraid
destroy your current volume
create two new ones (one for each disk)
reinstall apps
recreate shares (some on each volume)
restore files from backup
When you're done you won't have any RAID redundancy, so it is even more important to have a backup strategy in place.
Normally you just initialize the LUN, and the LUN container file takes space on the RAID array (like any other file). A thick LUN will take the full allocated size right away. A thin LUN can be overallocated - it will grow as you put more files on it. The thick version generally works out better, but if don't have enough space you could make a thin one.
If I understand you cerrectly, I can make a LUN an initialize it without loosing the data on the disk. Afterwards, I need to format the LUN. Can I do this without the risk loosing the data?
For the time being, I don't want to buy new disks or upgrade the NAS. I have this NAS now 3 years and my family and I have used about 150 GB of the 3 TB of space.
If I understand you cerrectly, I can make a LUN an initialize it without loosing the data on the disk. Afterwards, I need to format the LUN. Can I do this without the risk loosing the data?
A LUN is a virtual disk. It's just a 25 GB file as far as the RAID array is concerned.
You format the LUN on the PC (or whatever the iSCSI client machine is). That formats the virtual disk (e.g., writes to the 25 GB file), but doesn't affect anything else. The data on the NAS won't be touched.
