Gents, I am cuurently building a new system (THANKS to all who helped earlier!! http://www.ar15.com/forums/topic.html?id=71745) and have a question.

The MB I ordered came with a built in RAID controller. I know basically what RAID is but is it worth it? In what areas would it be benefical? Gaming? What? Also is it problematic? I don't want a headache!

Thanks again!

RAID is a sytem where your data is redundant over a series of disks. Your data is therefore less prone to failure.

If you have sensitive or important data that needs to be protected from loss, either mirror or stripe the data across two or more drives.

If your objective is simply performance, without a need to protect your data by "speading" it, forget RAID. It will slow you down.

Juggernaut

The MB type raid is typically good for RAID 0 and RAID 1.  Both REQUIRE two IDENTICAL drives.

RAID 0 is for SPEED.  It stripes the data across two drives, so that is can read and write from both simultaneously.  If either drive has a failure, you lose ALL your data.  The benefit is speed.  Gamers, and speed demons typically use this.  As a plus, you also get the total available data capacity as the two drives.  So if you have 2 40GB drives, you get 80GB of useable space.

RAID 1 is for REDUNDANCY.  It writes to both drives at the same time.  It is the same speed as a single drive on reads, and slightly slower due to bus overhead on writes.  It allows you to have one drive die, and the system will continue to run as normal, with all data intact.  Most servers us this technology on the OS volumes for system uptime in the case of a failure.  Downside is that for 2 40GB drives, you only get 40GB of useable space.

Either one is a plausible option.  I typically advise people AGAINST both.  The added speed is negligible for the common user in RAID 0, and the added redundnacy is typically not needed and expensive in RAID 1.  

Spend your money on something cooler.

Not true Jug.  RAID 0 offer NO redundancy or protection, and was strictly designed for speed enhancement.  I can go into detail on how this works if you like.  Real world, it is not used extremely often, but it is used in applications like database servers for testing maximum capabilities of throughput... for transaction log volumes, etc..

RAID 1 and RAID 5 are the other more common types of RAID.  Both offer redundnacy as you say.  RAID 5 (minimum 3 disks) actually offer INCREASED perfomance over a single splindle on reads.... especially when multiple users are accessing different files simultaneously.  More spindles per array = more performance.  Much more than a single drive.

But you are right, he probably doesn't need it.

Ditto. RAID is generally for servers where uptime and redundency is critical. Home systems can generally get by with a tape drive and drive imaging.

Slayer, agreed it is a waste for the avg. home PC.

But performance really wont suffer,  in fact, it will increase substantially for disk I/O (big bottleneck in the PC) under RAID 0, and be almost the same under RAID 1 (see above)

of course, most RAID on sysbds are weak, real raid are like RAID 5, spread data across several drives with parity and when you lose a drive, replace it and recreate the data from the info on the others.

No_Expert

FiveO,
I used to sell this type of technology, and others, for Compaq. I say used to because several months ago I was laid off. Anyway, here is an explanation. RAID means Redundant Array of Inexpensive Disk. They probably don't seem inexpensive to you but compared to the alternative they are. RAID is a data guarding technology. There are several different ways to implement RAID but the most common on smaller systems is to use RAID level 1 which is also called RAID 0+1 by some companies. What it does is mirror two hard drives to each other and it requires disk drives to be installed in pairs. For example, to use it you would need a RAID disk controller (don't try it with software drivers, its to problematic) and two disk drives of equal size. I will use two 18Gb drives in the example. Once all of the hardware is installed your operating system will only see 18Gb worth of drive space. However every time you write anything to the primary drive in the pair the controller makes an exact copy on the secondary drive. The result is that every bit of your data on disk is duplicated, or you could say mirrored, on a second drive. The controller takes its ability a step further. If either drive should fail it will continue to give you access to your data through the functional drive. The good ones will notify you of a drive failure. Depending on whose RAID solution you buy you can also get hot swap features so that if a drive does fail you can unplug it while your computer is running and plug in a replacement. The controller will then immediately begin to copy all data to the new drive to put you back into a full RAID 1 mode.

There are other levels of RAID used for systems requiring large amounts of disk space and these are normally implemented on larger servers or SANs. (Storage Area Networks - yes, storage can be networked) Those methods such as RAID level 5 are implemented differently and are more complicated to understand at a nuts and bolts level. However the intended result is the same. The disk system becomes fault tolerant and has a good deal of protection against data loss due to disk failure.

Do you need RAID? That depends on how valuable your data is to you and what the likely hood is of recovering from a loss of data. However, I can tell you this. All modern PC hard drives run the risk of failure. Truth is, it's not a question of "will it fail?" Its a question of when. Three years ago one industry study said that when a server does fail that 55% of the time it's because a disk drive failed.

Hope this helps you make a decision, good luck.

Ok.  But it still is.



It is?  You had better tell the engineers that!  Seriously, not to split hairs, but that is just not true.  It was developed over time to meet many needs.  Performance, and redundancy.

 

Not entirely true, as I know people who would pay for it, to have that level of protection, without the issue of backups.  Not recommended, of course, but that is why it is there.  



Absolutely false.  If you did a poll, you would find FAR more servers using raid 1.  Raid 5 is seen in file server and large database servers, mail servers, etc... for things hosting a large amount of data.  Fact is, there are many more servers running raid 1, which dont need the mutliple disks, like domain controllers, dhcp servers, print servers, specific application servers, web farms, etc..   Most enterprises I have supported have FAR more servers with only two disks.... running RAID1.



Again, not true.  The overhead is only on the writes.  Reads are the same speed as single spindle.... and actually can be much faster, since most RAID controllers add a hardware disk cache, which adds a performance boost over a single spindle attached to the system board SCSI.



Say again?  The replaced drive is only saturating the bus during a hardware rebuild of the data.  This is a few hour long process tops.  What's that got to do with anything?

FiveO,
One more thought on this. Backups!
Consider this, you do need some kind of a backup method. Eithe the whole system whic only works well if you can complete restore the whole system or you could just backup data. In which case you must plan on reinstalling everything (Windows and all applications individually) before you restore your application data.

You can back up using a CD R/W drive but plan on being at your computr for a while if you do a full backup. Tape is another option but plan on spending at least $300 for a unit with decent speeds and the ability to back you up on two or three tapes. USB or parallel port attached units offer lower prices but Jesus they are slow!  When you start to compare the cost of anything other than slow backup solutions to the type of RAID 1 cost you get into on an Ultra ATA or IDE based disk system RAID starts to look pretty good. For myself the next desktop system I build will have RAID for this very reason. I can add it to a desktop system for close to what I would pay for a good tape system and, a) it always works, b)it never forgets to back itself up and c)in the event of a disk failure I don't have to do a restore.

Sorry about that, you are correct. I didn't tell the whole story. Guess my mind was fixated on mirroring and striping. Raid 0 would offer a speed boost for data writes, but I had almost forgotten about it, since all we worry about on our servers at work is redundancy.

Either way, 10 to 1, he doesn't need it.

Juggernaut

Sorry about the poor grammar in my last post. Sometimes this computer takes a pause while I type and the keystrokes never make it to the screen!  Go figure.

Damn! Thanks for all of the discussion!!

I think that given the small speed increase and the apparent complexity I will pass on it, at least for now. I am pretty good about backing my files and such up on CD so the redundancy, while nice, may not justify the expense.

Thanks VERY much for all of the input! YOU GUYS ROCK!

I have had the opportunity to play with some different vender raid systmes.  The latest we are deploying is IBM Netfinity X350 with the 4HB controller which is a 4 channel ultra 160 RAID controller it supports 0,1,5,5E,10,1E0,50,5E0.  I have had the opportunity of setting up some huge arrays.  Last one was a 1E0 for a Rational Database server utilizinf 1E0.  It had 28 36.4 drives in one array.  That is about a terabayte of physical drive storage  - actually size is half that due to redundancy.  It is built for speed.  It is Raid 1E (enhanced Raid 1) Striped.  It allows you to span a mirror across multiple drives, kind neat.  Also have set up Raid 10 or 1+0 great for database servers.

Steve