iSCSI Best Practices - VMware, iSCSI, Microsoft

Recently, we came across the need to re-implement iSCSI for Microsoft, VMware and EMC environments. The goal was to reconfigure iSCSI using all best practices that are necessary to successfully design and implement iSCSI storage for an enterprise. We went through many different documents from VMware, Microsoft and iSCSI and squeezed out the best information we could find. Here is summary of what we discovered and hopefully it will help others out there trying to implement iSCSI SANs.

You can download the complete documents here:

HTML - iSCSI-Best-Practices-VMware-EMC-Microsoft

Word - iSCSI-Best-Practices-VMware-EMC-Microsoft

PDF - iSCSI-Best-Practices-VMware-EMC-Microsoft

VMware Virtual Network Concepts - Summarized (VI3)

Virtual Networking is new and confusing to many of us used to traditional networking concepts. We recently found ourselves struggling to resolve issues involving VMware environment and Link Aggregation. We thought it would be a good idea to put a document summarizing all the concepts of VMware Networking since it's new and huge. So here is the document that describes VMware networking in a nutshell (well, not really!).

HTML - VMware Virtual Network Concepts Summarized
Word - VMware Virtual Network Concepts Summarized
PDF - VMware Virtual Network Concepts Summarized

A Quick PowerShell Reference Pocketbook

As most of us already know that PowerShell is a new scripting language from Microsoft based on .NET framework. Microsoft and other vendors are heavily placing the scripting needs around PowerShell for administrative use. Specially starting Windows 2008 PowerShell has become an integral part of the Windows environment. Here is a quick reference from my studies of PowerShell language. Since I am already familiar with other programming and scripting languages, I used Dr. Tobias PowerShell E-book for quickly learning the syntax and semantics of PowerShell.

Here is a quick reference guide that I created for my self for future reference which I thought will also be helpful for others. Please remember this is just a quick reference for those who have some programming or scripting back ground.

You can download MS Word and PF versions from here:
Word - A Quick PowerShell Reference Pocketbook
PDF - A Quick PowerShell Reference Pocketbook

Statement Evaluation Order:

- Parenthesis ( ) are always evaluated first

Automatic Unit Recognition:

- Units like KB, MB, and GB can be used with numbers like 1MB + 2GB. Results are in bytes by default.

Windows Batch & Other Commands:

- cmd /c command-name

- use & to execute commands in quotes, i.e. & "c:\autoexec.bat"

- To execute a program in current directory, prefix program name with \ i.e. .\editplus.exe . Unless the folder is on the windows path $env:path

- Add folder to path: $env:path += ";C:\programs\Windows NT\accessories"

Cmdlet Convention: Use the forms of verbs and nouns i.e. Get-Help

Add, Clear, Compare, Convert, Copy, Export, Format, Get, Group, Import, Measure, Move, New, Out, Read, Remove, Rename, Resolve, Restart, Resume, Select, Set, Sort, Split, Start, Stop, Suspend, Tee (Split up), Test, Trace, Update, Write.

Cmdlet Parameters:

- Common Parameters i.e. ErrorAction, WhatIf

- Named Parameters i.e. string, string[]

- Switch Parameter i.e. boolean ($true,$false)

- Positional Parameters i.e. Get-ChildItem -recurse, -name, c:\windows *.exe

- Disable Parameters: Use -- or "-Parameter" (quotes) to disable parameter recognition

Variables:

- Definition:

- $syntax i.e. $company = “Axiom Dynamics Corp.”

- Typeless i.e. $one = 1

- ${special variable} i.e. ${I am special} = “Special”

- $assignment = value or “cmdlet Result”

- Multiple inline assignments are supported i.e. $ten = $10 = 10

- separate statements by ; i.e. $one=1;$two=2

- $_ - this reference

- Swap variable values:

$Value1 = 10; $Value2 = 20;

$Value1, $Value2 = $Value2, $Value1

$Value1

$Value2

- Virtual drive is a variable

- Write-Protected variables

- "backtick" character ’

- "." before the script file path to turn off restrictions on visibility

- Scope modifiers are private, local, script, and global

- Type: $variable.GetType()

- Type safety: [oneoftypes] $variable where,

[oneoftypes]: [array], [bool], [byte],[char],[datetime], [decimal], [double], [guid], [hashtable], [int16], [int32], [int], [int64],, [long], [nullable], [psobject], [regex], [sbyte], [scriptblock], [single], [float], [string], [switch], [timespan], [type], [uint16], [uint32], [uint64], [xml]

- Variable Options: "None","ReadOnly","Constant","Private","AllScope"

- Variable Validation Classes: ValidateNotNullOrEmptyAttribute,ValidatePatternAttribute,ValidateRangeAttribute,ValidateSetAttribute

Operators:

- Arithmetic:

- Hex are prefixed with 0x

- Operators: +, -, *, /, %

- Conditional: -eq, -ceq, -ieq, -ne, -cne, -ine, -gt, -cgt, -igt, -ge, -cge, -ige, -lt, -clt, -ilt, -le, -cle, -ile, -contains, -ccontains, icontains, -notcontains, -cnotcontains, -inotcontains, -not/!, -and, -or, -xor

- If/ElseIf/Else

- Switch w/ default

- strings (case sensitive)

- wildcards

- regex

- expressions,

Arrays:

- The comma always creates an array.

- Verify e.g. $a is [Array]

- Index starts at 0 and -1 is last element

- Force to return array by using @()

- Create New Array i.e.

- $arr = 1..4

- $arr = 1,2,3,4

- $arr = "1","2"

- $arr = 1

- $arr = @()

- Reverse Arrays

- New elements Can be added by using += operator

- Strongly Typed Arrays: [[int] ]$arr = 1,2,3

- Arrays (returns matching / unlatching members)

Hash Tables:

- Key-Value pair sep by ;

- Access/Modify using either [] or .dot

Note: Arrays and HT are references to data

Pipeline:

- Cmdlets To Pipe: Compare-Object, ConvertTo-Html, Export-Clixml,Export-Csv, ForEach-Object, Format-List, Format-Table, Format-Wide, Get-Unique, Group-Object, Import-Clixml, Measure-Object, more, Out-File, Out-Host, Out-Host, -paging, Out-Null (suppress output), Out-Printer, Out-String, Select-Object, Sort-Object, Tee-Object, Where-Object (?), Out-Default, Out-Host, * (wild card), Scriptblocks,

- Modes: Sequential/Streaming Mode

- ETS - Extended Type System: Emergency mode,

- $$ - last token of pipeline

Loops:

- ForEach-Object ("{indexes}") == %

- ForEach - works with collection

- Do/While, While, For, break, continue, :label

Aliases:

- Example: PowerShell Virtual Drives

$alias: Get-PSDrive

dir alias:

- Group-Object definition

- Create new aliases using Set-Alias, i.e. Set-Alias edit notepad.exe

- Save Aliases using profiles or Export-Alias/Import-Alias cmdlets.

- Life span of alias and function are only when PS console is open.

Functions:

- Syntax: myFunc { commands/code $args }, multi line (enter) / single line (;

- Calling: $function:tabexpansion | Out-File myscript.ps1/>file.ps1

- Write-protected functions: Set-Item function:{//code} -option constant

- Delete function: Del function:test,

- Arguments: Args: $args - spaces ""

- Parameters: function myFunc([type] $Param1=110, $Param2=$(Get-Date), [Switch] ParamN)

- Returns are array or return keyword or omit returns

- Write-Debug ,$ErrorActionPreference,

- Stop-Process -nameofFunction

- Dir function:

- $function: prompt

- Function {begin{}process{}end{}}

Object:

- New-Object: Creates new object

- Add-Member (NoteProperty, ScriptMethod, CodeMethod, Method)

- Properties and Methods: $objectName.PropertyName or $objectName.MethodName()

- Versioning: Major, Minor, Build and Revision

- -static, constructors

- Can load assemblies and COM.

Scripts & Other Language Integration:

- Windows Batch Files

- VBScript (Wscript //H:CScript - console, WScript //H:WScript – Windows)

- .\filename.ext

- Own: ps1.

- Before executing scripted created on other machines you must Set-ExecutionPolicy to RemoteSigned

- .\myscript.ps1

- Get-ExecutionPolicy, Set-ExecutionPolicy RemoteSigned

- md $env:appdata\PSScripts

- \myscript.ps1 Tobias,

- $($args[0])

- param ($path, $name), param ([string] $Name=$( ` Throw "Parameter missing: -name Name")

- [int]$age=$( `,. .\calcfunctions.ps1,

- . $env:appdata\PSLib\calcfunctions.ps1,

- {begin{} process{} end{}}

- Four Different Profile Scripts: All users[private],Current user[private]

Debugging:

- What-if

- Confirm:Low, Medium, and High, $ConfirmPreference = "Low"

- ErrorAction/$ErrorActionPreference:SilentlyContinue,Continue,Stop,Inquire

- $?

- Trap {}

- $_.Exception.Message

- ErrorVariable myError

- $Error

- Throw

- Write-Debug, $DebugPreference:SilentlyContinue,Continue,Stop,Inquire, Set-PSDebug –step

- @"

- {index[,alignment][:format]}