transfer speeds confusion

[digity]

I kicked off a backup over the network (SMB/CIFS) - Windows 10 computer to my FreeNAS server. Win 10 showed it hitting between 500 and 600 Mbps, the Network reporting tab in the FreeNAS webUI showed the same speed, but the Disk reporting tab in the FreeNAS webUI showed each of the 10 drives hitting roughly 14 to 15 MBps. So combined the 10 drives are doing 140 to 150 MBps total which is 1120 to 1200 Mbps... why is the disk transfer speed reporting double the network transfer speed?

 

[joeschmuck]

Honestly I've never thought of this but I suspect it has to do with the setup of your pool. Remember, in a RAIDZ2 youa re writing enough data to all the drives in order to support the complete loss of two drives and still your data is in-tact, so there is a lot of data. I'm sure there are other factors too, I'm just not up to speed on exactly how ZFS writes it's data and then reads it back I suspect to validate it.

 

[digity]

Honestly I've never thought of this but I suspect it has to do with the setup of your pool. Remember, in a RAIDZ2 youa re writing enough data to all the drives in order to support the complete loss of two drives and still your data is in-tact, so there is a lot of data. I'm sure there are other factors too, I'm just not up to speed on exactly how ZFS writes it's data and then reads it back I suspect to validate it.

It's a pool of 5 sets of 2x2TB mirrored vdevs... so I guess its double because of the instant mirroring when writing...?