hot plug vs hot swap

Hot swapping and hot plugging are terms used to describe the functions of replacing computer system components without shutting down the system. More specifically, hot swapping describes replacing components without significant interruption to the system, while hot plugging describes the addition of components that would expand the system without significant interruption to the operation of the system

Sometimes the term hotswap is used to mean hotplug but the two concepts are distinct. Normally a hotplug device needs to be shutdown before removal. By contrast, a hotswap device can simply be unplugged without risk of harm


References:
http://en.wikipedia.org/wiki/Hot_swapping
http://wiki.linuxquestions.org/wiki/Hotplug#Hotplug_vs_Hotswap

• HOT PLUG vs HOT  SWAP

Let's assume you are talking about a physical disk drive as the field replaceable unit (FRU).

Hot Swap means that you can remove the drive and replace it with another drive without significant interruption to the system.In case of a mirrored disk environment, the system should re-synch with the new drive to reestablish the mirrored pair. In the case of a RAID configuration, the system performance may be degraded until the drive is replaced and the checksum data is spread across the new drive, but again, there is no significant interruption to service.

Hot Plug is a little tougher. Hot Plug typically means that you can add a new FRU (a disk drive in our example), but you can not remove the FRU without taking some sort of outage. I say that Hot Plug is tougher in the sense that you need to be careful and not interpret Hot Plug as having Hot Swap capability.


Hot swap lets you insert and remove cards, PC boards, cables, and/or modules from a host system without removing power, Because of the need for High Availability (HA) systems, hot swap has quickly become part of every designer's vocabulary. To increase system availability, hot swap is used to reduce down time, simplify system repair, and allow for system upgrade. Because of these advantages, hot-swap solutions are finding their way into a wide variety of applications

Hotplug enables inserting but how swap enables inserting and removing withoung being going offline


http://unix.ittoolbox.com/groups/technical-functional/ibm-aix-l/what-is-difference-between-hot-swapable-and-hot-pluggable-3523526

• The term hot swapping means that changing the hard disk drive with out even switching off the power. Even if the disk drive fails then also the system is not halted for the purpose of even changing the hard disk

References:
http://www.youtube.com/watch?v=MRgUgHUSVtI
http://www.raid-data-recovery.net/raid-hot-swapping.html

• Both hardware and software RAIDs with redundancy may support the use of a hot spare drive; this is a drive physically installed in the array which is  inactive until an active drive fails, when the system automatically replaces the failed drive with the spare, rebuilding the array with the spare drive included. This reduces the mean time to recovery (MTTR), but does not completely eliminate it

Reference:

http://en.wikipedia.org/wiki/RAID#Hot_spares

Hot Swapping a Hard Drive in a Rack