Memo on RAID

What is RAID? RAID, abbreviation for redundant array of independent disks, is a technology to manage disk IO in multiple disks. (more accurate and detail version of definition is at Wiki (https://en.wikipedia.org/wiki/Standard_RAID_levels).

RAID has few different types and called RAID 0, 1, 2, 3, 4, 5, 6.

It’s not like I did background check on facts, but I hear, the most popular types are RAID 0 and 5 today.

RAID 0 evenly distribute data across n number disks.  It’s simple straightforward way to take advantage of adding multiple disks.  The risk, if one of the disk goes wrong, then it’s all gone.

RAID 5 distribute data across n number disks randomly, plus parity information on one of the disk, so if one of the disk is damaged, you can recover like nothing happened.

Next I will organize pros, cons, and theological speed of each RAID.

What is Azure Active Directory

What is Azure Active Director? and of course they have exact same title article covering exactly I wanted to know at https://azure.microsoft.com/en-us/documentation/articles/active-directory-whatis/.  So here is my short memo version.

Azure Active Directory is a service where you can manage things around credentials.  You can offer your app, API and other services based on credentials that you manage on Azure Active Directory.

For example, you have API service that is privately offering and want to manage accesses, you can do so through Azure Active Directory.