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LUN and Disk
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 ...
Zunderman wrote:
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.
I am using XRAID.
I just thought this:
If I turn off XRAID (and turn on Flex-RAID), I can make new partitions. I could create a new partition and put the LUN on that partition.
Now I have two question:
Are my thoughts right and can I make that partion without the risk loosing the data on the disk?
Zunderman wrote:
Are my thoughts right and can I make that partion without the risk loosing the data on the disk?
No, you will lose the data.
Zunderman wrote:
I am using 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.
StephenB wrote:
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?
There is around 2.5 TB free space on the disk. For now, I want to know how it works and test it. Because of this 25 GB should be enough.
StephenB wrote: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.
Zunderman wrote:
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.
For now I know enough. Thank you a lot!
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