Disk utilization high for larger disk after disk upgrade

[pomtom44]

Hi all.

Im not sure what information is needed to help troubleshoot so please let me know if I miss something out.

I have a fairly new unraid install on a decommissioned box I got my hands on.
I originally installed it using the 146gb drives which came with it.
I have started swapping them out for some spare 500GB drives I had laying around, till I can put some money aside to get some 2tb drives.

Most of my 146gb disks were around 50-60% usage
But when I swapped one of them out for my 500GB drive, that drive blew out to 80% usage, and the others dropped down to 30-40%
I assumed it was something to do with the high water setting, and asked around but no one could help me figure it out

I changed my settings to most free in a hope to try spread the load out a bit more. And left it for a few days to let the data sort its self out 
(most of the data is cctv footage at the moment so changes pretty frequently)

The other day I added a second 500GB drive, and the same thing happened
both my 500gb drives are at 76% used, and the rest of the 146GB drives are now at around 20% used each.

Normally I wouldn't mind about it, as I know unraid is doing its thing, but i have gotten a few alerts for high disk usage on those two drives as it is over the 70% warning line.

Am I missing something obvious? or is this normal / expected?

 

Edited May 15, 2023 by pomtom44

[itimpi]

You are likely to get better informed feedback if you attach your system’s diagnostics zip file to your next post in this thread.

[pomtom44]

24 minutes ago, itimpi said:

You are likely to get better informed feedback if you attach your system’s diagnostics zip file to your next post in this thread.

Attached
 

nas01-diagnostics-20230515-1707.zip

[itimpi]

Your disk utilisation is about what I would expect with the default High Water Allocation method which is discussed in some detail here in the online documentation.  I suspect you do not quite understand how it works?

 

The High Water points are based on the size of the largest drive (not a % used)  so in your system this would be 233GB.  At this point disk1 and then disk2 would be used until this point is reached

The next point is 116.5Gb and then disks would be used in turn until this point is reached.  It appears that you probably reached this point.

The next point would be 58.25 GB and then all drives would be used in turn until they were down to this amount free.

etc.

 

I would recommend switching back to High water as the Most Free option is the least efficient as it keeps switching drives thus keeping them spun up but that is up to you if you prefer to keep all drives with roughly the same amount of free space.

[pomtom44]

10 hours ago, itimpi said:

Your disk utilisation is about what I would expect with the default High Water Allocation method which is discussed in some detail here in the online documentation.  I suspect you do not quite understand how it works?

 

The High Water points are based on the size of the largest drive (not a % used)  so in your system this would be 233GB.  At this point disk1 and then disk2 would be used until this point is reached

The next point is 116.5Gb and then disks would be used in turn until this point is reached.  It appears that you probably reached this point.

The next point would be 58.25 GB and then all drives would be used in turn until they were down to this amount free.

etc.

 

I would recommend switching back to High water as the Most Free option is the least efficient as it keeps switching drives thus keeping them spun up but that is up to you if you prefer to keep all drives with roughly the same amount of free space.

Thats what I thought, but I was just worried that I was getting the high disk usage alerts on disk 1 and 2 when the rest are pretty much empty.
I assume thats because of the large gap in size difference between them all?
The 147GB disks are bringing the high water line down for those disks meaning more data is being written to the larger disks?

I assume the answer is go with high water, and just leave the warnings till I can get more balanced drive sizes?

[itimpi]

6 minutes ago, pomtom44 said:

I assume the answer is go with high water, and just leave the warnings till I can get more balanced drive sizes?

You can set drive specific warning levels by clicking on the drive on the Main tab and providing values for that drive that are different to the global setting.