Hot add and CBT performance

[pcrebe]

Hi,
after a Replica job (hot add + CBT enabled + Optimal + LAN target) i've this e-mail log:

Success 1 Start time 8:02:12 AM Total size 120.0 GB Backup size 2.4 GB
Warning 0 End time 8:20:43 AM Data read 6.7 GB Dedupe 1.0x
Error 0 Duration 0:18:31 Transferred 2.4 GB Compression 1.0x
Details
Name Status Start time End time Size Read Transferred Duration Details
sbs2008 Success 8:03:39 AM 8:20:34 AM 120.0 GB 6.7 GB 2.4 GB

The job processing rate is 111 MB/s but in realtime statistics i've:
Hard Disk 1 (80.0 GB) 5.2 GB read at 13 MB/s (CBT)
Hard Disk 1 (40.0 GB) 1.5 GB read at 12 MB/s (CBT)
Busy: Source 38% > Proxy 58% > Network 12% > Target 91%
Are these the real speeds or it indicates only CBT block that are read, may someone explain it? Are slow, medium or high speed?
Source Datastore MD3000i near line SAS 7200 rpm
Target Datastore PE2900 Raid10 SATA 7200 rpm
veeamVM registered on target esxi but stored in a primary Raid1 datastore
Proxy1 veeamVM target esxi
Proxy2 vCenterVM source esxi
Automatic proxy selection that always use for source and target proxy Proxy1.

Thanks,
Carlo

[Gostev]

Next to hard disks there is real speed at which the changed blocks of the corresponding disk were read.

[pcrebe]

Hi Gostev,
disabling the CBT value MB/s increases a lot (7x) but the job duration time becomes 2x, so is (my) an error of assessment not of hotadd performance.

Anyway how can i understand if the job speed is right?

Thanks,
Carlo

[Gostev]

Well, if you can fit your backup window, then the job speed is right and if not, then you need to improve it.
From the percent busy stats you have posted above, your bottleneck is clearly the target storage speed.