iSCSI "space threshold"

[mleopold]

hi,

i'm using FreeNAS exclusively for iSCSI and this "space threshold" things keeps spinning in my head.

just to be entirely sure:
the target global "Pool Available Space Threshold (%)" and extent "Available Space Threshold (%)" configurations are referring to the https://doc.freenas.org/9.10/sharing.html#extents recommendation "it is recommended to keep the used space of the pool below 50% when using iSCSI", is that correct?

that means i can use more than 50% of my zpool SIZE for extents volsize, i just have to be sure (and can configure "thresholds") that the pools CAP doesn't exceed 50%, correct?

thx
matthias

 

[dlavigne]

Did you find an answer for this?

 

[Stux]

hi,

i'm using FreeNAS exclusively for iSCSI and this "space threshold" things keeps spinning in my head.

just to be entirely sure:
the target global "Pool Available Space Threshold (%)" and extent "Available Space Threshold (%)" configurations are referring to the https://doc.freenas.org/9.10/sharing.html#extents recommendation "it is recommended to keep the used space of the pool below 50% when using iSCSI", is that correct?

that means i can use more than 50% of my zpool SIZE for extents volsize, i just have to be sure (and can configure "thresholds") that the pools CAP doesn't exceed 50%, correct?

thx
matthias

I believe that's right. The advise is that performance degrades (or the risk of fragmentation increases) above 50% utilization. Also, the first half of HDs is nearly doubly faster than the last half.

So, it's actual sectors used not sectors potentially used.

 

[mleopold]

I believe that's right. The advise is that performance degrades (or the risk of fragmentation increases) above 50% utilization. Also, the first half of HDs is nearly doubly faster than the last half.

So, it's actual sectors used not sectors potentially used.

thanks, this is what i assumed in the first place and it's the only interpretation that makes sense. it's rather important to me, because i'm relying on this when planning rather large installations + investments, but by know i'm sufficiently sure about it.

thread can be closed.