[Ham-Computers] RE: Multiple drives, is there a way to . . .

[Hsu, Aaron (NBC Universal)]

Hi Phil (et al),

Yes, it is possible to do what you're describing via RAID-0 (RAID zero).  RAID-0 is truly a misnomer as there is no redundancy, but it's a RAID form not the less.  Basically, RAID-0 is spanning - the data "spans" across the drives, so if you have two 200GB drives, the RAID-0 volume will show up as a single 400GB volume.  Three 200GB drives will make a 600GB RAID-0 volume and so on.  RAID-0 is the fastest of all RAID types as there is no checksum calculations nor redundant writes.

Typical RAID arrays require drives of identical size.  if any drive is smaller, then the smallest drive size is used as the "base".  So if you have a 200GB and a 250GB drive, then both will be treated as 200GB each and the RAID-0 volume will be 400GB in size.  An exception is if the RAID controller supports "JBOD" (Just a Bunch Of Disks).  In JBOD, the full capacity of each drive is used, so with the same example just mentioned, the JBOD volume size would be 450GB.


*** DANGER, WILL ROBINSON, DANGER! ***

RAID-0 (and JBOD) comes with a risk - if any drive in the array fails, then the data in the entire array is lost.  So the recommendation for most is to use RAID-0 only for temporal storage - not archives.  An example would be a scratch drive for video editing or for a PVR/Tivo.  Another example is a hard core gamer who wants the absolute shortest "load time" when playing games (to be the first to "jump in" a game level).  So be aware of this limitation of RAID-0/JBOD - make backups of all data you want to permanently store if it's on a RAID-0/JBOD array.


Depending on your system's motherboard, it may already have a RAID controller built-in (many do these days).  If so, you may only need to attach the drives to the RAID controller and enable RAID functionality.  NOTE: you'll need to backup the data on the original drives first as once the RAID volume is created, everything on the drives is wiped when the RAID volume is created.  You can also add an inexpensive RAID controller for under $50 - these and most motherboard-based RAID controllers utilize the PC's CPU for much of the RAID functionality.  Higher priced RAID controllers include their own CPU's to take the burden off the PC.

There are also external USB/Firewire/eSATA enclosures out there that will create the RAID-0/JBOD volume for you.  Most of these also support RAID-1 (mirroring) and possibly RAID-5 (striped parity)  One of the most innovative is the "Drobo" (http://www.drobo.com), but it's also one of the most expensive - many great reviews and designed to be very simple to operate and includes some proprietary data protection.

So, Phil, going by your description(s), it sounds like you need an "archive" which would eliminate RAID-0 as a possibility.  An exception is if you have a way of backing up the RAID-0 array.  My suggestion is to buy a 750GB or 1TB drive (about $170 & $250, respectively) and not consider RAID-0.  Or, buy smaller drives and catalog by drive - each drive has a genre/program type/etc.  You may also want to consider using a desktop search engine like Google Desktop to assist with searches - Google Desktop builds it's database in the background and searches are fairly quick.  Never really used it as I don't have a large library, but I know people who love it.

One other alternative...build a RAID-5 array.  This is redundant, but requires at least 3 drives of the same size (smallest size drive rule applies if they're not the same size).  You lose the capacity of one drive, but the array is redundant - if one drive fails, the array itself still works and you can replace that drive and have the array rebuild itself.  So if you have 3 200GB drives, the RAID-5 capacity is 400GB.  If you have 5 200GB drives, the RAID-5 capacity is 800GB.  With some RAID controllers, you can even add a second redundant drive (sometimes called RAID-6) so if two drives fail at the same time, the volume is still usable.  RAID-5 is most commonly found in data centers, sometimes combined with RAID-1 (mirroring) to form RAID 5/1 - this requires twice as many drives, so it's only used on "mission critical" data.  If you have an old PC laying around, setup a simple Linux server with a RAID-5 volume.

BTW, I'm in a similar boat as you - my PVR has 800GB of TV shows on a 2-drive RAID-0 array that need to be archived - slowly putting them onto DVD's now.  And, with the new High-Def formats, I need to reconsider exactly how I'm going to handle 8GB files (1 hour of HDTV).

73,

  - Aaron, NN6O



-----Original Message-----
Sent: Wednesday, February 06, 2008 6:21 PM
Subject: [Ham-Computers] Multiple drives, is there a way to . . .

Hi All,

I have what may seem like an odd question.  But here goes.  My XP-Pro SP3 
tower has two internal hard drives, an 80 and a 500.  OS and most programs 
reside on the 80GB, all my MP3 Old Time Radio files (~300GB) reside on the 
500GB "D" drive.  There is also a 320GB "H" external drive (Firewire) used 
as a backup drive for the MP3 stuff. That drive is, for all practical 
purposes full and needs replacement with a larger drive (probably a 500).

I can probably get another 320GB external drive much cheaper than a 500, or 
for that matter, an external drive "case" for the 320GB SATA drive that came 
out of the main machine when I installed the 500, making that a 3230 GB 
external drive.

My question is this.  Is there a way to make TWO external hard drives appear 
as one drive of the combined size of both?  That is, where I could just 
"copy" all files from the "D" drive to the two external drives without 
having to manually "split" the files and put some in drive "I: and the rest 
in drive "J", or whatever.  The reason I ask this is, I have a very 
"structured" folder hierarchy for all my Old time radio shows, by genre, 
program etc so that I can easily find something.  With over 36,000 shows I 
HAVE to have it well structured  as I'm often replacing files with ones that 
have better audio etc, and need to easily find what I have without having to 
do repetitive "file searches" ;^)


73 de Phil,  KO6BB
http://www.geocities.com/ko6bb/index.html
http://ko6bb.multiply.com/

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