Minnesota Web Developer | A little something about everything...

Minnesota Web Developer

A little something about everything...

How does Raid Parity work? Raid 6, Raid 5, Raid 4, Raid 3, Raid 2 - XOR Calculations

In order to create redundancty with parity data you simply need to make the parity bit create an even number thus requiring only one drive to backup an unlimited number of drives.

XOR calculations are done by compairing the remaing data with the parity data. To simplify how parity works here is a quick demonstration with an 5 disk array.

 

Stripe 1:

110101000101111011010011 (Drive 1) Cylinder A1

010110010110101101011100 (Drive 2)

110111011101110110110101 (Drive 3)

101010110110110111011010 (Drive 4)

--------------------------------------------

111110111001000111100000 (Parity Data)

 

Now take any one drive away and you can calculate what the data would be by simply making the sum of the remaining data even, this is called XOR calculations.

Cylinder: This is all of the data that is read within one rotation of the disk.

Stripe: This is the data across all drive of the same position Cylinder(ie A1/B1/C1D1 or A2/B2/C2/D2 with the Letter being the Disk and the number being the Cylinder placement)

 

How to boot from a USB Drive (flash drive or external storage)

Toss in any bootable CD/DVD Rom along with your usb drive and type the following command:

xcopy e:\*.* /s/e/f g:\

This is assuming "e" is your rom drive on the computer you are creating the bootable usb drive and "g" is your usb drive. Update as needed.

Notes:

  • Remove any third party software from the usb drive. (make a copy if you think you will want to put it back on later)
  • You should format the usb drive in fat32.
  • Be sure your usb drive has enough space on it to accept the data.
  • The system you are going to be using the usb drive to boot from will need the option to boot from usb in the bios, some older systems do not support this feature and you will need to create a boot loader to do this instead.

Method #2, older bios updates

  • format your usb drive as fat32
  • copy the following win 95/98 boot files to the drive(be sure not to include any memory loaders)
    • COMMAND.COM
    • CONFIG.SYS
    • IO.SYS
    • MSDOS.SYS
  • copy your bios files
  • update as instructed by your motherboard, hardware controller manufacture

boot.zip (200.94 kb)

How to copy windows install from cd/DVD to USB without any extra software.

Open CMD.exe as administrator then do the following:

  • Type: "diskpart"

a new window may open or it may start in the current command window,

at the DISKPART> prompt type in the following.

  • list disk
    • (make note of the disk that is your usb drive, if you are not 100% sure do not continue as you may cause data loss)
  • select disk #
    • enter a number based on the previous noted disk(your usb drive)
  • clean
  • create partition primary
  • select partition 1
  • active
  • format fs=ntfs quick
  • assign
    • this will create a new drive on your system, make note of the drive letter.
  • exit

in the admin command prompt window type the following:

  • (DriveLetterofyourCD/DVDinstaller):
  • cd boot
  • bootsect.exe/nt60 (DriveLetterofUSB):
  • (DriveLetterofUSB):
  • xcopy (DriveLetterofyourCD/DVDinstaller):\*.* /s /e

That's it, your done. You can now boot and install from USB.

How to stay secure online: Passwords, security and compromised sites, Oh my!

Best things to remember for password and email security,

  • Passwords, Have a secure password with a minimum of 8 characters including small and capital letters, 1 or more symbols, as well and at least 1 number.
    • Don't use easy to guess passwords that contain pets, kids, parents and/or sibling names or birth dates.
    • Make your password something you would never share with anyone, many people use a favorite color, food, etc.. which they also post to social media sites like facebook.
    • Separate your passwords, never use the same password for everything, if a website that you use is compromised(updated: recent example linkedin database compromised) then all of the stuff you use could become compromised. Generally its a good idea to use three or more passwords with variations of those passwords that you can change around for example H3l!0WoR!D, Hell0w0r!d, HelloW0rlD. This allows you to use basically the same password in many places but if one place is compromised it will minimize the impact since you are using a variations of the passwords in each place.
    • Try to avoid needing password security questions and hints, don't give real answers that a potential hacker can find with little effort.
  • Public terminals, Don't use public terminals to check your email or bank information as they can contain key-loggers which will compromise your account to hackers including government agencies.
  • Free WiFi, Don't use public unencrypted free WiFi to send and receive email unless you are browsing and checking email with SSL only. (https:// for sites and webmail or SSL in your email configuration)

This may seem like a lot of work but having identity theft or compromised personal information will be a lot worse.

How to use Internet Explorers built in FTP Client with Active FTP

Open Internet Explorer, click tools > Internet options > Advanced > scroll down until you see "Use Passive FTP" and verify that this is unchecked.

This will force Internet Explorer to use Active FTP rather than Passive FTP.

Now type in ftp://_yourdomain .com_ in the address bar, when prompted enter the login credentials: your_username and then Your_Password after which depending on your version of Internet explorer you may need to perform the following steps; click view > Open FTP Site in Windows Explorer and reenter your login credentials. Now you can drag, drop and edit files as needed from windows explorer.