grep particular details from a file using powershell

Assuming you have at least PowerShell 3.0 ( For the -Raw switch of Get-Content. If you don't an easy change can account for that) we can convert that text file into a PowerShell object which would make data manipulation easy.

$fileDataObject = (Get-Content C:\temp\data.log -Raw) -split "\b(?=Name\s+:)" | Select-Object -Skip 1 | ForEach-Object{
    New-Object -TypeName PSObject -Property ($_ -replace "\s:\s","=" | ConvertFrom-StringData)
}

$fileDataObject | ForEach-Object{"{0,-20}{1,-25}" -f $_.Name,$_.CreationDate} | Set-Content "C:\temp\output.txt"

Take the raw data from "C:\temp\data.log" and split the file into chunks where the lines are Name : text. That would return five groups, first one being empty, and we skip the first one.

Those chunks of data are asking to be converted to hash tables using key=value data pairs. We then convert all the colons that are in between white-space into equal signs so satisfy the needs of ConvertFrom-StringData. This transformation is captured into $fileDataObject. You can see its contents below which have been formatted for this answer.

Name  CollationName    Edition  MaxSizeGB MaxSizeBytes ServiceObjectiveName ServiceObjectiveAssignmentStateDescription CreationDate          RecoveryPeriodStartDate
----  -------------    -------  --------- ------------ -------------------- ------------------------------------------ ------------          -----------------------
abc   xxxxxxxxx        System   5         5368709120   System               Complete                                   02-Jul-14 4:14:19 AM  02-Jul-14 4:14:19 AM   
def   xxxxxxxxxxxxx    Standard 250       268435456000 S2                   Complete                                   25-Jan-15 6:39:41 PM  01-Mar-15 3:00:00 AM   
ghi   xxxxxxxx         Standard 250       268435456000 S2                   Complete                                   25-Jan-15 3:19:01 PM  01-Mar-15 3:00:00 AM   
hjiyt xxxxxxxxxxxxxxxx Standard 250       268435456000 S2                   Complete                                   11-Mar-15 11:07:30 AM 11-Mar-15 11:37:31 AM  

Since you just want those 2 columns of data in the output we can arrange that using the format parameter. I saw in the OP that you have 20 character spacing for the Name so that was enforced for the output as well using the -f operator.

Assuming no preexisting data in "C:\temp\output.txt" you should see the output you desire.

$sourcePath = "C:\test.txt"
$targetPath = "C:\output.txt"

$output = New-Object System.Text.StringBuilder

Get-Content $sourcePath | 
    Where-Object { $_.ToString().StartsWith("Name") -or $_.ToString().StartsWith("CreationDate") } | 
    ForEach-Object { 
        $value = $_.ToString().Split(@(':'), 2, [System.StringSplitOptions]::RemoveEmptyEntries)[1].Trim()
        $temp = New-Object System.DateTime
        $isDateTime = [DateTime]::TryParse($value, [ref]$temp)
        if ($isDateTime) {      
            $output.AppendLine("`t`t`t`t`t$value")
        }
        else {
            $output.Append($value)
        }
    }

Set-Content $targetPath $output.ToString().Trim()

You can improve this where required, but with your sample data shown here it should work.