What does RAID mean for HDDs?

Question

I'm not very well acquainted with the hardware of computers. I've done a lot of research, however, because I've started window-shopping for an I7 build. I've become more knowledgeable when it comes to CPUs, Video Cards, RAM, etc. I am, however, still in the dark when it comes to HDDs. I don't really know what the differences between SATA, PATA, etc. are. If you could answer that, please do so on my other question (http://answers.yahoo.com/question/index?qid=20091018174257AAz9fEF). As for this question, in fairly plain English, what does RAID mean and how would it affect my computer's performance?

Answer 1

RAID - Redundant Array of Inexepensive Disks.



This is a setup where you have multiple (theoretically any number) disks acting like a single drive. You use this to produce various useful effects:

1) Reliability: one disk can fail but you can still get your data from the good disk. (Using a drive to record error correction information or one drive to completely mirror another).

2) Speed:, you can retrieve some of the data you want from one disk, and the rest of the data that you want from a another drive at the same time. This is done by using "data-striping" (byte one written/read to drive 1 second to drive 2, third to drive 3, fourth to drive 1, fifth to drive 2, sixth to drive 3, seventh to drive 1, eigth to drive 2, etc.)

3) Extra capacity: Or you can simply add extra drives and your so-called "single drive" will seem to get bigger. This needn't involve data striping.



If you have a couple of disk drives then you have to choose between reliability, speed / capacity, but with more you can have all of them, though reliability (will always be at the expense of capacity).

Answer 2

Raid Means

Answer 3

Are you sure it's setup as RAID 0? If so, you would have a single volume C:\ drive that's just under 2 Tb. RAID 0 is only used for performance and will not provide any measure of redundancy. I'm afraid that you've lost all hope of recovering from this error. Hopefully, it is setup as RAID 1. This is where the two disks are exact copies (mirror) of each other. You have to use the RAID manager and remove the bad drive from the array so that you have only one drive. You can then get your files off the drive before setting your RAID array back up as a mirrored set.

Answer 4

What Does Raid Stand For

Answer 5

SATA is a newer faster physical interface for connecting HDD to a HDD controller on a motherboard or host. SATA 1.0 has an interface speed of 1.5Gbits/s. SATA 2.0 is common now and is twice that. SATA 3.0 is about to come out next year and is 6Gbps interface speed.



PATA interface is old (aka IDE or EIDE) and some mATX motherboards do not even support the IDE interface anymore. It had a Max Interface speed of 1Gbps but since it was parallel, the interface only supported one data stream at a time even though it could read and write at the same time, a single stream could never fill the 1Gbps bandwidth threshold, which is why SATA is preferred.



The actual read and write speed of the HDD itself will be different so look for benchmarks on HDD IO performance. Generally for playing games and casual computer use, you want a HDD with fast average READ speed. If you do a lot of media production and editing, look for a balanced READ and Fast WRITE speed

http://www.tomshardware.com/charts/2009-3.5-desktop-hard-drive-charts/h2benchw-3.12-Avg-Read-Throughput,1010.html



That benchmark is for Spindle Magnetic drives and not SSD drives. Also note that spindle speed does not always produce a faster drive. Aerial Density is also very (and possibly more) important when it comes to drive performance.





RAID arrays are used in both enterprise and workstation use. There are different types of RAID array that allow parity or IO load balancing or both across a cluster of interconnected HDDs. RAID 1 and RAID 5 (and RAID 6) provide some sort of data redundancy - RAID 1 uses two exact HDDs to mirror the data on each drive so if one drive fails no data is lost. The downside of RAID 1 is that if you buy two 1TB drives, you only get 1TB of storage in the array because there is bit for bit mirroring. Also, RAID 1 can reduce performance depending on RAID controllers and file systems.



RAID 0 is the opposite of RAID 1 and is used to double the performance IO of two (or more) drives in the array. Data written to the RAID 0 array is split amongst the drives so if 10 MB needs to be written, 5MB gets written to each drive, hence effectively doubling performance in theory, but slightly less than double in practice. There is NO data redundancy in RAID 0, and if one drive fails, you lose the data on all the other drives in the array. The other benefit of RAID 0 beside the performance increase is that the HDD capacity of the array is pooled together an appears as one physical drive. So if you have three 1TB drives in RAID 0, the OS will see only one 3TB HDD.



RAID 5 or 6 (or RAID 50) is often used in practice because it is a combination of RAID 1 and RAID 0 - it gives data redundancy and improved striping performance. You need at least three drives in a RAID 5 array, but if only one drive fails, no data is lost. Also, performance is good and the HDD pool capacity is fair too (not 1/2x but not 2x) compared to RAID 1 and RAID 0.



RAID 50 is often used in enterprise. JBOD is often used for SOHO applications like file servers or NASes.



Most people would say to avoid RAID arrays for desktop use unless you know what you are doing and buy a dedicated RAID card because RAID controllers on most motherboards (as well as Software RAID) do not provide the performance that most people need.



Also in RAID arrays, the drives must be the same capacity (and preferably the same speed) otherwise space is Wasted. JBOD does not waste space but can or can not offer any data parity depending on the product used.





In short, AVOID raid.



For a desktop, get a fast drive that you will use for the OS and Applications/Games, then get some high capacity drives for storage. Some gamers opt for an Intel SSD drive for their OS drive as they are blazing fast and have great Random Read Speeds.



Also, consider a i5 CPU build - It is the best bang for buck on a mid tier system and uses a newer LGA1156 socket that won't be phased out if you consider a Core2 Core2Quad LGA775 option. The i5 also overclocks really well.

http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=16

With i5, motherboards are cheap (P55 express chipset) and it uses only dual channel DDR3 instead on Triple Channel DDR3 so you can save money on RAM.

Answer 6

RAID: Short for Redundant Array of Independent (or Inexpensive) Disks

It means basically this: Raid is copying one hard drive to the other by means of a RAID hardware card. To run RAID you need at least two hard drives - there are several levels of RAID - each increase insuring more fault tolerance. RAID is typically set up on server computers where data preservation is critical. For more on the levels of RAID:

http://www.webopedia.com/TERM/R/RAID.html



SATA hard drives or (Serial Advanced Technology Attachment)



ATA devices are also commonly called IDE, EIDE, Ultra-ATA, Ultra-DMA, ATAPI, PATA, etc. (each of these acronyms actually do refer to very specific items, but are commonly interchanged)

Answer 7

your other question says it was deleted...



RAID is redundant array of inexpensive disks...



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



that really kind of explains it. I'm running a RAID 0 in my computer where the data is split and saved onto two disks AT THE SAME TIME. allows for faster disk speeds and in other setups allows for backups and data security.

Answer 8

raid is definitely the schematic bones for the hdd to work for it. i.e. its arrangement, form, etc



and the ide and sata are different..



ide are older hdd they use a wide type of wire to connect hdd to board



and sata is smaller wire while it delivers faster data..

Answer 9

RAID is where you have 2 hard discs working together. Gives you more speed or security.

Answer 10

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