This should give you that information, Note that i have appended the Aggr Size information in TB
Function Get-VolOverEighty {
Get-NaVol | ? { $_.used -gt 90 } | select name,aggregate,used,@{Name="VolumeAvailable(GB)";Expression={[math]::Round([decimal]$_.Available/1gb,0)}},`
@{Name="VolumeSizeTotal(GB)";Expression={[math]::Round([decimal]$_.sizetotal/1gb,0)}}, `
@{Name="AggregateSizeTotal(TB)";Expression={[math]::Round([decimal] ((Get-NaAggr -Name $_.Aggregate | select -ExpandProperty SizeTotal)/1tb),2)}},`
@{Name="AggregateSizeAvailable(TB)";Expression={[math]::Round([decimal] ((Get-NaAggr -Name $_.Aggregate | select -ExpandProperty SizeAvailable)/1tb),2)}},`
@{Name="AggregateSizeUsed(TB)";Expression={[math]::Round([decimal] ((Get-NaAggr -Name $_.Aggregate | select -ExpandProperty SizeUsed)/1tb),2)}}
}
Get-VolOverEighty