Category Archives: Quick Tip

PowerShell Quick Tip- Letter Frequency

With a list of Surnames in a text file I wanted to see how many start with A, how many with B, and so on. This is my PowerShell solution:

(Get-Content .\surnames.txt).Substring(0,1).ToUpper() |
  Sort-Object | Group-Object |Select-Object Name, Count

Example Input (surnames.txt file):

Adams
Smith
Jones
Bloggs
...

Example Output:

Name Count
---- -----
A      162
B      372
C      365
D      193
E      187
F      198
G      154
H      321
...

ESXi UNMAP not working on Replicated EqualLogic Volume

Symptoms

  • The VMware vSphere ESXi UNMAP command doesn’t release space on some or all volumes on a Dell EqualLogic SAN array running v8 firmware (may apply to other versions too). Using the following command in an SSH session to a 6.0u2 host (again, will apply to other versions):
    esxcli storage vmfs unmap –l MYVOLUMENAME
  • The volumes are VMFS5 (and always have been- they haven’t been upgraded from VMFS3).
  • Replication is enabled for the volumes that won’t rethin.

image

Cause

UNMAP doesn’t work on the EqualLogic when Replication is enabled. It doesn’t return an error to the SSH session, and the temporary rethinning file is still created, but the disk is not thinned.

Solution

Disable replication on the volume, re-thin the volume using the UNMAP command, then re-configure replication. Unfortunately this means the entire volume must be re-copied to the replication partner and this may impact bandwidth usage and replication schedules on larger volumes.

image

Finding Deprecated VMFS Volumes

Following an upgrade to vSphere 6, hosts popped up an error message reporting that some old VMFS volumes were found on the host. Whilst these still worked, it would be prudent to tidy them up and replace them with modern datastores. The message is:

“Deprecated VMFS volume(s) found on the host. Please consider upgrading volume(s) to the latest version”

image

Whilst this highlights that there is an issue, the GUI message doesn’t indicate which volumes (or how many) are affected. The following quick bit of PowerCLI produces a table of the datastores with a VMFS version of less than 5.

Get-Datastore |
 Where-Object { $_.ExtensionData.Info.VMFS.MajorVersion -lt 5} |
 Select-Object Name, FreeSpaceGB, CapacityGB, @{n='VMFS Version';e={$_.ExtensionData.Info.VMFS.MajorVersion}}

Example Output:

Name           FreeSpaceGB CapacityGB VMFS Version
----           ----------- ---------- ------------
VOL-VM01            574.77    2047.75            3
VOL-VM02           1924.05    2047.75            3

Quick Tip- Deleting iOS Apps

iOS OneDrive AppProblem: I’m trying to delete an iOS app from an iPad (9.3.2) , I hold down my finger on the icon on the homescreen till they all jiggle but no little x appears on the icon.
Solution: In the Settings App, under “General” then “Restrictions” ensure that “Deleting Apps” is allowed. Go back to the home screen and try again- the small x should now appear.
Enable Deleting Apps on iOS