Retrieving disk capacity with powershell - powershell

Question

I made this code to count disk capacity, but when i run it with only the SSD in my laptop i get 0GB. after I insert USB/external space it count the ssd + the USB.
$disk = Get-WmiObject Win32_DiskDrive
$capacity = 0;
for($i = 0;$i -lt $disk.Count; $i++){
$capacity = $capacity + [math]::round(($disk[$i].Size/1GB),2)
}
Write-Host $capacity "GB"
This works fine -> $disk.Size
Why does it not take the first [0] in my for loop?

Answer 1

I cannot answer why your for loop is failing without observing your environment, but there is almost never a use-case for it. You should instead opt for a foreach loop:
$capacity = foreach ($disk in Get-WmiObject -Class Win32_DiskDrive)
{
[Math]::Round(($disk.Size / 1GB), 2)
}
"$(($capacity | Measure-Object -Sum).Sum)GB"

Answer 2

Assuming Windows 10 since you didn't mention OS and the CMDLETS in Windows 10 are so much better. *See at the bottom for a Windows 7 version.
For disk information, I prefer using Get-PhysicalDisk, like this for example:
$DiskInfo = foreach ($disk in Get-PhysicalDisk) {
[string]$name = $disk.FriendlyName
[string]$type = $disk.MediaType
[int]$capacity = $disk.size / 1GB
[pscustomobject]#{
"Type"=$type;
"Name"=$name;
"Capacity (GB)"=$capacity;
}
}
$DiskInfo
In my environement where I have one SSD and one mechanical HDD, it will return:
Name Type Capacity (GB)
---- ---- -------------
SAMSUNG MZ7TY256HDHP-000L7 SSD 238
ST500LX025-1U717D HDD 466
If you wanted information for JUST the SSD for example, you could do this :
$DiskInfo = foreach ($disk in Get-PhysicalDisk | Where-Object {$_.MediaType -eq "SSD"} ) {
[string]$name = $disk.FriendlyName
[string]$type = $disk.MediaType
[int]$capacity = $disk.size / 1GB
[pscustomobject]#{
"Type"=$type;
"Name"=$name;
"Capacity (GB)"=$capacity;
}
}
$DiskInfo
Which returns only the SSD:
Type Name Capacity (GB)
---- ---- -------------
SSD SAMSUNG MZ7TY256HDHP-000L7 238
Explanation: Foreach disk connected, store name, media type and capacity in variables. *Divide byte capacity by 1GB to get a better number to look at.
Still in the Foreach, create a custom object at every iteration containing the 3 variables.
All put together, you can then output your variable DiskInfo which contains all the objects.
If on Windows 7, media type isn't available so you can't use it. Instead you can do:
$DiskInfo = foreach ($disk in Get-WmiObject -Class Win32_DiskDrive) {
[string]$name = $disk.model
[int]$capacity = $disk.size / 1GB
[pscustomobject]#{
"Name"=$name;
"Capacity (GB)"=$capacity;
}
}
$DiskInfo
Which will return something like:
Name Capacity (GB)
---- -------------
SAMSUNG MZ7TY256HDHP-000L7 238
ST500LX025-1U717D 466