RAID for Noobs

PS: I'm really bored and have nothing better to do, and I'm really ADD and I need to vent my never ending stream of consciousness about gadgets.

 

Congrats you have just been upgraded from a RAID nub to noob because you took the initiative to learn. Remember nub = bad, noob = neutralish (leanin' towards good xD)

Growth of Demand for RAID

So yea RAID is definitely becoming more and more feasible now that desktop-class hard drives are dirt cheap (around $11.6/GB) and its becoming more necessary because hard drives are so much bigger but they are haven't gotten much more reliable. Desktop-class drives (eg. your average SATA drive) are as prone to failure now as they were in the last couple years and maybe even more so now that they have more space. So now the chance to lose your data on larger drives is super high (heck I don't know how many early adopters of RAID-1 had one of their drives fail).

Benefits of RAID

All RAID levels increase read performance. In addition all RAID arrays (other than RAID 0) provide redundancy. They all provide different ratios of performance, redundancy, and capacity. By using RAID one is able to get much more out of their disks then they could by using them alone. One is able to spread parity information across disks and provide redundancy with less usage of capacity then simply backing up. One is also able to have a disk automatically backup in real time by having their computer simultaneously write to two hard disks. The possibilities with RAID are simply endless.

Motherboard RAID

Now en days, most motherboards have RAID (even the low end <100 ones) but the only problem (which very few people know) is that they are only 32-bit and now is when that RAID is starting to become useless. Integrated RAID has the same performance/specs (although more through output) as PCI RAID cards. They can only support up to 2TB arrays, which is very small. The standard drive now en days is around 1TB so soon enough all of those will be obsolete as sizes climb a little more. Also they are 100% software so they put more load on your CPU and memory and are inefficient.

A Changing RAID Card Market

So now more and more people need dedicated RAID cards. In addition, RAID cards are pretty cheap now. In addition more 64-bit cards are on the market and 32-bit cards are starting to become phased out due to their ubiquity within motherboard chipsets. Now that most computer users already have very basic RAID chipset in their motherboards, RAID card manufacturers are trying harder than ever to sway consumers. Currently 64-bit cards are becoming extremely inexpensive, with entry level models as low as $13.

Any card that uses the PCI-express interface is 64-bit and the lowest level PCI-express interface, PCIe x1, has a rate of 2.5gb/s (320MB/s) vs. 133 MB/s on PCI. It's typically very common on most motherboards and you will probably never use PCIe x1s for anything else.

 

Now these will run you around 20 or 30 dollars for a software only solution.

 

The only problem with these is that the theoretical output is only 320MB which is around what SATA II is (300MB/s), most current hard drives will probably not go past SATA I (150MB/s) during normal usage. (Raptors are only SATA I). So these will be fine for 2 normal SATA drives. But these are definitely not usable with SSDs.

Software vs. Firmware vs. Hardware

There are three types of RAID implementations that are used in desktop computers. Firmware RAID uses a chipset or an expansion card in order to run the RAID software at the low BIOS level. Software RAID does not rely on any hardware and RAID is done at a higher, operating system level. Both the software and firmware RAID implantations run low level software that relies on the host computer's CPU and memory to do parity and error correction calculations. hardware RAID; on the other hand, processes calculations completely separate from the host computer's CPU and memory by using an XOR processor with its own dedicated RAM.

Software RAID

Software RAID can be very good as it is free and it works similarly to firmware RAID. One advantage that software RAID has is that on a 64-bit system one can have arrays above 2TB (as opposed to 32-bit PCI firmware cards which can't). Software RAID is also very good for large laptops with multiple drive bays. Most 17'+ laptops have at least two hard drive bays and typically users run their hard drives in RAID 0 as it does improve performance. The desktop version of vista only supports RAID 0, which is good for laptops as most laptops do not have RAID controllers, and there is no way to add a RAID controller to a laptop. In addition, laptop drives are small, and can be easily backed up through an eSATA port.

Software RAID has a variety of problems. Software RAID is reliant on the OS and is not as stable as firmware RAID. An array using software RAID might not be fully compatible with other operating systems. Software RAID can cause problems with the Operating System's boot processes as most bootloaders do not correctly recognize software RAID. LILO is the only bootloader that natively recognizes software RAID.

Firmware RAID

Firmware RAID is similar to software RAID performance wise but they are more compatible. These basically act as a layer between the disk drives and the OS and help alleviate some issues such as problems with booting from an array. Firmware RAID cards and chipsets present the OS with the array as if it were one disk and firmware cards will work with any OS who has a driver written for them. Most large brands and integrated chips support SATA, BSD, and SATA as well as windows. Although some of the more off-brand firmware cards only work with windows. Firmware RAID is more reliable because it works on a lower level the software RAID and has control of the BIOS.

Hardware RAID

Hardware RAID on the other hand uses CPU and RAM separate from the main PC. These are more efficient because all the data is processed in one place and it can things that software RAID can't do. It's kind of like the difference between a 256mb dedicated video card and 400 mb integrated video card using shared RAM, even though the system has extra RAM to accommodate and maybe even higher clocked RAM the dedicated video card will still always be the winzor.

 

 

Write-back

With hardware RAID you can greatly increase performance using the write-back cache, which holds what's being written in its memory and tells the OS that it's done. (Francis, David) Write-back cache increases performance significantly but it holds the data in its RAM until your computer idles. This also is a little risky because it holds memory longer (PC MAG). You can get a battery for your card which will keep the RAM powered so it doesn't lose data, and this completely takes away the risk with write-back (unless of course the power goes out for like 2 days). But batteries cost 100 dollars and if you're getting an entry level card it's not really worth it.

Product Opinion: Although in this field Rocket RAID is very good because there batteries just hang off the card and don't take up a precious bracket like the others.

 

But for most of us we can just put write-back on as it's not the most you can lose is 100 or 200 MB of data. Or you can just have your computer connected to a UPS (you really should anyways) and just have it shutdown the PC, then poof risk gone and no $100 battery needed. Or you can just not turn on write-back cache if you're running an important database and use write-through.

Write Hole

This brings me to one caveat with RAID. The greater the amount of drives the more the "write hole" is a problem. The "write hole" is the possibility of a loss of data when the system crashes. This is mostly in RAID 5, but also to some extent in RAID 6 and the other high levels. Basically, this happens when the system crashes in the middle of a write and doesn't finish writing parity data. This can mean that if there is a hard drive failure and you don't check the drives then you could lose some data. If you are using RAID 5 where this is more of an issue than you can just make sure to check your drives after every system crash and to check your drives every once in a while.

Upgradability (Card)

One more caveat about RAID that can really get you are that all of the RAID cards and software RAID are proprietary so once you use one RAID card you might not be able to upgrade your RAID card, especially to a different brand. Also software and hardware RAID are not compatible so you're going to have make that decision early unless you want to face heartache when you need more capacity. My recommendation, go a step higher than what you need. If you are doing 3 drives than go with a PCIe x4 card as you might want more drives in the future. If you are just using 2 1.5TB drives than you can go with low end PCIe x1 as you probably have the space to move the data if need be. Also if you're getting a PCIe x4 card you mind as well get it hardware. Most PCIe x4 cards are hardware anyways. It would be incredibly painful to use a firmware RAID card in RAID 5 or RAID 6 on even the best rigs.

Overall, Hardware RAID cards have had a significant drop in price in the past couple months so PCIe x4 entry level hardware card is only 50 or so more dollars than an equivalent firmware card. You really won't ever need PCIe x8 cards for a desktop (well you know what I mean, I'm not saying you'll still be using PCIe x4 card when computers have 50 cores and 100 TB drives, although 640K of RAM is definitely enough for me (Gates)

SCSI Cards

In addition, if you have to pick between a SATA card and a SCSI card of similar price (even if the SAS is just a little bit more) go for the SCSI. SCSI is a high-end server class standard which also is compatible with SATA. You can buy a SAS or Mini-SASx1 to SATAx4 fanout cable from Amazon or anywhere for else for about $15. One mini-SAS is equivalent to four PCI lanes and one lane is used for SATA cable. I am also relatively certain that those SATA cables can be split with a SATA port replicator. It's also a much cleaner install as there isn't 4 separate wide red cords in your case. In addition, SAS disks are much faster (around 15K) for the same amount as money as a VelociRaptor. They have more throughput than SSDs and much better write speeds, while being as cheap as a high-end SATA hard drive.

Upgradability (RAID Level)

One should pick and plan their levels for any future upgrades they might want to do. This could depend on how powerful your card is, the size of the hard drives you are using, your computer case, and how much you're willing to spend on hard drives. RAID Levels can be migrated but they can only descend. You cannot migrate a RAID 5 setup to RAID 6 but you can migrate a RAID 5 to RAID 0. When doing migration one can only migrate to a level that requires less space overhead. The only way to move up in a RAID level is by backup up your discs and redoing the whole setup. So pick a RAID that has the right balance of redundancy and performance.

Price

When it comes to RAID you can never have too many drives so your best off just filling up your computer case with smaller drives. 4 500GB drives is a better than 3 750 because the more drives the faster. And for the hard drives pick a size that isn't too low that you can continue to upgrade as they get cheaper. In addition bigger hard drives are slower and they have more latency. Bigger hard drives are especially slower when they add more platters, the more hard drive platters the slower. This is one of the good things about RAID, you can get faster hard disks with less platters. But really the platters and size of the drives don't make as big of a difference. Just look to see what the best GB/$ ratio. ATM oddly enough the most spacious drives have the most value…although there is so many problems with them…so good thing we have RAID eh? And although SSDs are all the rage now, SCSI drives are much much much cheaper.

Caveats

GPT Disks

In Windows Vista, (and with a patch to XP) Microsoft added GPT support. GPT is considered the next step up from the greatly aging MBR. It has a superior partitioning scheme and it allows for more partitions and does not require the use of logical partitions, but more importantly it allows for partitions larger than 2 Terabytes. The only caveat to GPT Disks is that windows cannot boot from them. GPT Disks can only be used as secondary data drives. GPT is supported by most other operating systems such as BSD, OSX, Linux, Solaris, etc.

32-bit

32-bit Operating Systems cannot read partitions bigger than 2 Terabytes. This is a physical hardware limit in the same way that 32-bit Operating Systems cannot use more the 3GB of RAM. In addition 32-bit controllers cannot read arrays greater than 2 Terabytes. All cards that use the older PCI interface are 32-bit as PCI itself is 32-bit. In addition onboard motherboard RAID controllers are 32-bit unless they explicitly say otherwise. PCIe RAID cards are typically use a 48-bit interface but some extremely cheap cards might not, so double check if you are buying a low-end card.

PCI/PCI-X

Stay away from cards. These are the cards which use the older PCI interface. The PCI interface is about as big as a PCIe x16 slot. The PCI interface is very slow and only has 133 MB/s of bandwidth so it can barely handle one hard drive. They are also 32-bit. PCI-X cards are longer but they have a notch so they can fit in PCI slots. The PCI-X interface was only on server motherboards and even PCIe x1 is faster than it. Overall stay away from PCI/PCI-X cards, they are obsolete.

Ace Recommends

Solutions

1. RAID 0 Drives
   
   1. Conventional – Firmware/Software (Vista Disk Manager)
      
   2. SSD- Entry Level 2-port Hardware
      
      1. HighPoint RocketRAID 3120 PCI-Express x1 SATA True Hardware RAID Controller – Retail $129 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816115047
            
2. RAID 1 Drive
   
   1. Firmware
      
      1. Just use your chipset. Though if your trying to use x2 1.5 TB get one of these.
         
      2. PROMISE FastTrak TX2650 PCI Express SATA / SAS Controller Card RAID 0/1 JBOD – Retail $70
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816102139
            
         2. Good name brand card, is also SAS which is always a +
            
      3. Koutech KW-5103R5 PCI Express SATA II Controller Card RAID 0/1/0+1/, RAID5 w/ SATA Mulitiplier KW-5566 – OEM $40 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816104005
            
         2. Nice card. It's an unknown brand but for 40 dollars with a multiplier that's not bad at all. I wouldn't recommend for actually doing RAID 5 as you won't be able to expand…remember cards not compatible.
            
3. RAID 01/10 Drive
   
   1. 64-bit hardware card
      
      1. Adaptec 2240900-R PCI Express 4-lane 2.5 Gb/s SATA 1430SA Kit RAID 0/1/10 JBOD – Retail $100 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816103058
            
         2. Good cheap card that supports RAID 10 and cheapest PCIe 4x card. Adaptec is a large brand and it's not an off brand which is a plus
            
4. RAID 5
   
   1. Firmware
      
      1. Will have slow performance
         
      2. HighPoint RocketRAID 2310 PCI Express x4 (x8 and x16 slot compatible) SATA II Controller Card RAID 0/1/5/10 JBOD – Retail $159 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816115050
            
         2. This is probably the best one as it has 4 SATA/SAS slots which are interchangeable…that's quite a luxury. It's also an express x4. You really shouldn't use an x1 for more than 2 drives as that's all one lane can at max support.
            
         3. Its only $10 more than the SATA version and includes SATA cables. No brainer…
            
      3. LSI LSI00132 PCI Express SATA / SAS MegaRAID 8204ELP Kit 4-Port 3Gb/s RAID 0/1/5/10 – Retail $179 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816118087
            
         2. LSI is a good brand and this has the same specs as the rocketRAID. I personally like rocketRAID but LSI is considered a solid brand and this is only an extra 20 dollars so it pretty much down to brand preference.
            
   2. Hardware
      
      1. HighPoint Rocket RAID 4310 PCI-Express x8 SATA / SAS Controller Card RAID 0/1/3/5/6/10/ JBOD – Retail $229 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816115063
            
         2. Amazing card. I ended up getting this card and it really is a sweet card. Awesome XOR processor that cuts through RAID 6 like butter. It really is fantastic. I mean the SATA equivalent to this is 50 dollars more and has a much older proc.
            
      2. Areca ARC-1210 PCI-Express x8 SATA II Controller Card RAID 0/1/1E/3/5 JBOD - Retail
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816131003
            
         2. Areca is a great brand that always gets rave reviews. This card is PCIe 8x so I guess you could use a port multiplier although I don't know if the card is even support 8 lanes. I was going to get this card before the 4310 came out. The 4130 is cheaper, faster, is sas, has more modes, and is just sweet. Its also PCIexpress x8.
            
5. RAID 6
   
   1. Hardware
      
      1. HighPoint Rocket RAID 4310 PCI-Express x8 SATA / SAS Controller Card RAID 0/1/3/5/6/10/ JBOD – Retail $229 4/17/2009
         
         1. http://www.newegg.com/Product/Product.aspx?Item=N82E16816115063
            
         2. Yea same one, this card is made for RAID 6 and it is the only one below 300 dollars with this processor. SAS is always a +
            

 

What I think…

I think RAID is really going to start to explode in desktop computing. RAID is about the only thing that really is bringing up desktop computing. As laptops are becoming more popular and supplanting the low-end computers, high-end desktop PCs will still stick around. No matter what happens PCs are still going to have a place. Hard drives just keep continuing to keep falling and falling in price but like I said reliability is still the same. Hard drives are still mechanical parts and they just fail. Hard drives have a finite lifetime, maybe it's that they are controlled by magnets, maybe it's because they are mechanical, or maybe they just break. But one thing is for sure we can't just pretend like hard drives don't fail. Hard drives fail all the time for all different reason. Hard drives are delicate pieces of machinery that are the first thing to break in PCs. And it's not like Hard Drives are just going to go away. It will be a long time before SSDs supplant, if at all. SSDs are showing a lot of problems and aren't always stable for computing stuff. Not to mention you definitely can't be doing number crunching in CAD or video processing with your shiny new Quad core if your using an SSD. SSDs are just very disproportionate when it comes to read and write. In conventional hard drives read and write aren't too much different. Personally I'd take a SAS drive any day of the week because they have less problems and aren't incredibly overpriced.

On another note the face of RAID really has changed. It's become mainstream and it's become a household name every computer enthusiast knows. RAID just has so many uses in so many different environments. The original idea behind RAID is a simple one, through a bunch of random cheap mainstream drives together and see how much power when we can get out of em…and heck it worked.

 

 

 

RAID Level Glossary:

 

RAID 0 "Striping"

This greatly raises performance, although there is some debate because it increases output and not latency. Write performance is definitely improved though. RAID 0 is never to be used to store data as it has a higher failure rate than individual drives. This is because when it writes it writes half of the data to one disk and half to the other. The files are actually split and written to both discs in "stripes" of a certain amount. It is the only RAID level in which Windows Vista allows.

RAID 0 definitely gives some sort of performance gain (Torres) although in real world situations it doesn't give a huge performance boost with standard hard drives. It is more noticeable in server environments, as RAID 0 doubles throughput (eg. Bandwidth, how fast it can transfer a file). Throughput is not typically as important on desktops as latency. RAID 0 does not decrease latency and in some cases can increase it. Although hard drives only see modest but very noticeable performance increase, SSDs show huge performance gains. In addition, SSDs are perfect for RAID 0. SSDs have a very small failure rate as they have no moving parts, incredible latency, yet have typically exponentially less capacity than conventional hard drives. Due to SSDs low latency they can use the additional bandwidth, in addition SSDs have significantly less write performance than conventional hard drives and thus they greatly benefit from the increased write performance of RAID 0.

WD Raptors are also widely used in RAID 0 as they are quick and small. WD Raptors are the best hard drives for using as a boot drive.

Typical Usage: RAID 0 drives are typically used as boot drives while a second array or standalone hard drive is used for data. Can also use a "budget" SSDs in a desktop for more bang for your buck.

Bottom Line: All and all if you have two smaller drives lying around or a laptop go for it. If you really want to have such crazy performance that your friends will sneak into your house just to see how fast your computer boots and loads games, use SSDs in RAID 0.

Caveat: Firmware RAID Cards are not recommended for RAID 0 with SSDs. Especially the Intel ICH9R RAID chipset.

Disks: Unlimited, but typically 2 are used.

RAID 1 "Mirroring"

Mirroring is the simplest form of RAID. Mirroring simply has your computer write data to both hard drives. It's very simple and doesn't really require hardware RAID as there isn't too much processing necessary. If one hard drive dies that drive is simply replaced and the array is rebuilt. Does give a read performance increase as files can be read from both hard drives simultaneously.

Bottom Line: Uses 50% capacity which is quite a lot. Though, it is easy to use and has the least failure rate. Also doesn't really need hardware RAID. One hard drive can also be removed and used to move files to another computer or for additional backup.

Disks: Two, pairs are independent of each other.

RAID 0+1 "Mirror+RAID"

RAID 0+1 isn't a true RAID standard, it is a nested RAID standard but it is one of the more widely supported and used nested RAID level. RAID 0+1 consists of two groups of RAID 0 sets in a RAID 1 set. RAID 0+1 has more performance than as the drive are striped. RAID 5+ levels; in addition, it can be split back up and each RAID 0 can be accessed individuals. That is where it's advantages end. It is not as fault tolerant as the RAID 6+ levels and it uses older bit correction technologies rather than parity error correction. It is expensive and drives can only be added in pairs. It can only have one drive removed before error loss ensues. It also has high latency, power usage, and heat as every drive has to move together

Bottom Line: For a fileserver and not for a desktop, stay away from it.

Disks: Minimum of 4 drives, can only add in pairs.

 

RAID 5

RAID 5 is used mostly in higher end builds and typically uses hardware RAID. It is a happy medium between RAID 1 and RAID 0. It uses the more reliable parity bit system which is spread across all of the drives. If one drive fails than the parity information from the rest of the drives can be combined to recreate the failed drive. Thus it has much more available capacity than RAID 1 and RAID 0+1.

RAID 5 has very good read performance but it has poor random and small file write performance. RAID 5 is slow at writing small files like bittorent downloads and database operations similar to but to a lesser extent to SSDs. RAID 5 has a lot of trouble and will become greatly slowed down by writes smaller than a single stripe. A stripe is usually 64KB and files that are written that are smaller than 64KB as it has to read the data and parity files twice. (Standard Raid Levels - Wikipedia)Thus RAID 5 is geared towards data drives and not boot or program drives. RAID 5 has the most prevalent write hole. This is where parity data is not fully written and if the drive is not checked and repaired there can be data loss while rebuilding the array after a drive failure. (Standard Raid Levels - Wikipedia) RAID 5 has the least redundancy of any RAID Level and should not be used for a large amount of discs.

Bottom Line: Do not use as boot drive and do not run programs like bittorent or a usenet downloader off of the RAID 5 array as small random chunks of data will slow down the RAID 5 array. If configured properly a RAID 5 array will have very good performance. Using RAID 5 with firmware RAID will cause very slow write rates.

Disks: Minimum of drives. Can add any number of drives to the array.

Usage: Data storage using a moderate amount of drives. Stick to a raptor for your boot disk.

RAID 6

RAID 6 works in exactly the same way as RAID 5 except it stores one more drive worth of parity data. Thus it takes off two hard drives off of the array. The benefit of RAID 6 is that there a hugely diminished chance of a data loss during a rebuild. RAID 5 has a chance of having bad parity data due to an unnoticed write hole or just a hard drive with bad sectors. Hard drives don't just fail, it is a gradual process and even with RAID 5 data can still be lost. Also a hard drive can fail during the rebuild because of being abnormally taxed and this can cause a weak drive to fail at the worst possible time. If two hard drives fail in RAID 5, all of the data is gone and the chance of recovering anything meaningful is slim to none.

The only problem with RAID 6 is that it has more overhead because it has to do twice the parity calculation. This is why almost all firmware RAID cards leave out RAID 6 because it is simply impossible without a RAID card. Although with a decent RAID card there will be no difference seen between RAID 5 and RAID 6 as the RAID card will do all of the work independently of the main computer. RAID 6 with a newer XOR processor optimized for RAID 6, such as the IOP348, should give RAID 5 performance with RAID 6.

RAID 6 also has a reduced write hole and a lot less problems with data corruption as it has twice as much parity data. RAID 6 is becoming more and more popular as hard drive prices go down.

RAID 10 "Stripe+Mirror"

RAID 10 (or RAID 1+0) is the most popular nested RAID used on desktop computers. It has a variety of benefits including performance, low overhead, and fast random and small writes. RAID 10 performance wise does not have any of the disadvantages of RAID 5. It is very good with small writes and is made for database work. It does not have any parity which is an advantage and a disadvantage. RAID 10 is much faster at small writes because it does not need to go through all the parity overhead when writing files smaller than a single stripe. Although this lack of parity causes RAID 10 to be very fault intolerant, and even though it is a 4 drive system with the same capacity as RAID 6 it can only handle the removal of one hard drive. It also has a less efficient error checking system so it's more likely to have an imperfect backup. RAID 10 definitely is good for a lot of people. Although RAID 10 only has 50% capacity.

RAID 10 at four drives is much faster than RAID 5/6. Although the more drives the more 5 and 6 catch up and RAID 10 will lose a lot. RAID 10 has to move all the drives together the more drives the more latency and slower they are. Where RAID 5/6 get faster as they grow and they don't need to move all of the drives together.

Bottom Line: If you are 100% sure your sticking with 4 drives stick with RAID 10. Although it is not very upgradable as you need to add pairs and you lose 50%. All the drives added after 4 drives in RAID 6 have no loss. RAID 10 definitely has its benefits. It doesn't require hardware card because it doesn't have any parity calculations to do. It also can make a great boot disk.

Disks: Minimum of 4 drives. Must add in pairs and has 50% capacity.

JBOD "Spanning"

I'm just putting this here so everything knows what that JBOD thing you see everywhere is. JBOD is not RAID. It is just lumping a bunch of disks together so the OS sees them as one (hence. Just a Bunch of Disks). It doesn't have any real advantages or disadvantages because it doesn't really do much. It's probably not a bad thing to use if you're using vista (vista only allows JBOD and RAID 0) and want to put a bunch of discs of different sizes together. I guess it's good if you want to put a bunch of disks of random sizes together in one volume.

Ranks

Name	Performance	Redundancy	Overhead
RAID 0	1	N/a	1
RAID 1	3	1	1
RAID 0+1	2	4	2
RAID 1+0	2	3	3
RAID 5	4	5	4
RAID 6	5	2	5

(Kozierok, Raid X+Y vs. Raid Y+X)

Works Cited

Francis, David.

Gates, Bill. Interview with Bill Gates. 1993. Smithonian. <http://americanhistory.si.edu/collections/comphist/gates.htm#tc44>.

http://www.pcmag.com/encyclopedia_term/0, 2542,t=write+back+cache&i=54893,00.asp. PCMag Encyclopedia: Write Back.

Intel. Intel IOP348 I/O. 16 April 2009 <http://www.intel.com/design/iio/iop348.htm>.

Kozierok, Charles M. 17 April 2001. 16 April 2009.

—. Raid X+Y vs. Raid Y+X. 2001. 16 April 2009.

RAID - Wikipedia. Wikimedia. 16 April 2009 <http://en.wikipedia.org/wiki/RAID>.

Schulz, Greg. RAID Levels Defined. 27 June 2007. Tech Target. 16 April 2009.

Standard Raid Levels - Wikipedia. Wikimedia. 16 April 2009 <http://en.wikipedia.org/wiki/Standard_RAID_levels>.

Torres, Gabriel. Does Raid0 Really Increase Performance. 1 November 2006. 16 April 2009 <http://www.hardwaresecrets.com/article/394/6>.

 

 

1. Cause I'm not a douche and I like to give credit where it is deserved.)
   
2. Cause it is always good to compile from a variety of sources)
   
3. Refs make you sound more like you know what you're talking about (although I usually do))
   
4. Cause the authors of those are probably a lot smarter than I am :))