I'm trying to figure out whats true about hard drives. I really couldn't find the answers anywhere on the forms.

1st Do raids combine speeds of drives. Example: 2x 5400 rpm 250 GB = 1x 10800 rpm 500 GB drive; 3x 7200 rpm 500 GB = 1x 21,600 rpm 1.5 TB drive.

2nd If you raid 0 hard drives dose it shrink the table or space used to format the hard drive deviding the table amungst the hard drives.

3rd The requirements for setting up a raid, and the stability (I've really heard some weird stuff here)

4th Importance of drive speed is for speedy large file transfer and not nessisary for game; just fine on 5,400 rpm. (I'm pretty sure that false but I've made a habit of being wrong)

Some of this stuff seems a little far fetched like having 6x 7,200 rpm drives raided to one 43,200 rpm drive. (would be sweet)

I haven't seen any guides to this kind of stuff here. Maybe the guides section sould be expanded to contain more basic info like this. Basic info is being overlooked as stuff that everyone should know but dosn't I guess. I don't even know what the ram timings mean.

Maybe I just overlooked the info and it just need a sticky or somthing.

Tk had a nice hard drive guide that he posed in July but it didn't adress thease questions, it just talks about the stranths and weaknesses of drives.

Quote: Ide / Parallel ATA (pata) Older technology. speeds run from 33MB/s to 133MB/s Sizes run from 100mb to 750gb Comes in 3 Sizes 3.5", 2.5" and 1.8" (laptop size) Pro's Cheap - You will get the most bang for the buck. To install most operating systems, there are no drivers needed! Uses Standard Molex Plugs Comes in 3 Sizes 3.5", 2.5" and 1.8" (laptop size) Cons's Speed, its the slowest of the Bunch. When put into raid configurations, they have a higher fail rate. They have no protection from bad sectors on the disk. cable management - bulky cables Sata1 Speeds are slighty faster then there ide counterparts. This version has been phased out of production. speeds run from 133MB/s to 150MB/s Sizes 40gb to 1TB Comes in 2 Sizes 3.5" and 1.8" (laptop size) Pro's Faster then ide. Work great in raid configurations and are a much more cost effecent then scsi. Thin connecting cables.. makes cable mangagment easy have 10k Rpm Models. hot swapable. Cons's special power plug needed. Older sata drives were converted ide drives, so preformance suffered. External Hdd Cases cost much more Sata2 / sata 3.0 speeds are 150MB/s with a burst speed of 3gb/s Sizes 80gb to 1TB Comes in 1 Size 3.5" Pro's Work great in raid configurations and are a much more cost effecent then scsi. Thin connecting cables.. makes cable mangagment easy Burst speed gives huge improvment on overall prefomance. Hot swapable Cons's special power plug needed. External Hdd Cases cost much more No 10k Rpm models as of yet. SCSI Technology is as old as Ide, but has been constantly updated speeds are 33MB/s to 320MB/s Sizes 2gb to 300gb Comes in 1 Size 3.5" Pro's Fault tolerant. Not all of the drive is used, so if there is a bad sector on the disk, it gets replaced with the unused part. gives scsi hard drives a much longer life. Speed. it is not as fast as the burst speed of a sata2 drive, but it has a overall faster contstant speed. Drives come in speeds up to 15k Rpm, giving them the fastest seek times if the bunch. hot swapable. Cons's Expensive. 300gb sata drive will run in the 80$ range, same scsi320 drive will be 1200$ Loud. the faster the drive, the more like a jet engine it sounds. Most workstation boards do not have onboard scsi cards, so a card will need to be purchased. When you are using a card, you are limited to the bus speed of the pci / pcie slot. things have gotten better with pcie, but the cards still cost an arm and a leg wire management is a pain.. there are some rounded cables out there.. but they cost arm and a leg... In summary, the best bang for the buck is the sata 2 drives. if you are a gamer, look into a striped sata2 setup, or if you have the $$ look for 10k sata hard drive

Wikipedia RAID


Multiple drive don't make fast RPM's. They just use all the drives RPMs to the fullest.

Smaller writes on more than one drive, while the one drive writes the other seeks. With one doing half the work and the other doing half the work, the drive speed up access times.

Its like having a job to do, as one human, then adding another to help you do that job. Things are speeded up to a point.

Wiki's are very helpful in learning simple things like RAID.

Quote: Originally Posted by s1ugh34d Wikipedia RAID Multiple drive don't make fast RPM's. They just use all the drives RPMs to the fullest. Smaller writes on more than one drive, while the one drive writes the other seeks. With one doing half the work and the other doing half the work, the drive speed up access times. Its like having a job to do, as one human, then adding another to help you do that job. Things are speeded up to a point. Wiki's are very helpful in learning simple things like RAID.

I can't beleave I didn't Wiki that, any way it's exactly the way i thought I jsut had a couple of friends insisting on drive raids working as i mentioned.

I'ved built my raid setup not to long ago because i wanted to experience it & see if it's any good

what i found out was that YES! it's Faster then single drive but only in Raid 0

but be ready to do somme testing , because you'll get some options with raid like stripe size
my raid controler (on-board nforce 3) offers 4k ,8k ,16k ,32k ,64k ,128k for stripe size

so i begain with the default setting 64k but the results was only 20Mb/s (84 Mb/s) more then single drive sata (64 Mb/s) using HDTach to test.
but i "soon" find out that my max speed was when i was using 8k or 16k of stripe size now i was reaching a bit over 120 Mb/s of average speed.

btw you've got to clear you disk data then format & reinstall windows every time you choose a differente stripe size it's a long process but at less you'll know what stripe size is good for you.

already post a thread about my experience & tought that people would benchs ther hd just for fun to compare but i guess nobody was interested in?

http://forums.pcapex.com/results/111...enchmarks.html

For those too lazy to go to Wikipedia here is the short version of what RAID is and what I am going to talk about to answer your questions.

RAID = Redundant Array of Independent Disks.
RAID 0 = Striping = writing data across 2 disks
RAID 1 = Mirroring = writing the same data to 2 disks
RAID 5 = Striping + Parity, requires min of 3 disks
RAID 10 or 1+0 = Striping and Mirroring, requires 4 drives

Okay, so now that is out of the way, here are a few other concepts you need to understand to fully appreciate what goes on when you use RAID.

The speed of a disk has no impact on RAID beyond the impact it has on the performance of the drive overall. In other words, the only thing you need to know about disk speed is that all the disks in the array need to be the same speed and faster is always better.

Transfer Rate:
The rate a drive transfers data is a function of several factors. First is the number of platters in the drive. A drive with 2 platters will transfer data faster than a drive with one since there are more read/write heads to do the work.

Second is the speed the platters rotate. As I said before, faster rotation = faster data transfer and faster seek times.

Third is the interface that the drive has with your computer. SATA 3.0gbps is faster than SATA is faster than IDE etc.

Finally you have the amount of cache memory on the drive. As you might suspect, more is better.

RAID 0
RAID 0 attempts to improve your overall performance by increasing the number of platters that your "drive" has by making multiple physical drives look like 1 drive to your system. The pros are that you will generally get faster performance, though there are certain environments where this is not true, but they are not ones we PC Enthusiasts will generally find ourselves in. Also, your total storage space is the total of the two drives. So if you put two 100gb drives in RAID 0 you get 200gb of storage. The con is that if a drive fails, you lose all of your data since it is written across both drives.

RAID 1
RAID 1, like RAID 0, requires 2 drives. The difference is that instead of writing data across the drives it actually write the same exact data to both drives, producing a mirror copy. You will find that RAID 1 offers some performance gains over a single drive, but not much. However, what you do get is protection. If a drive should fail you have an online backup, the mirrored drive.

RAID 5
RAID 5 is familiar to anyone who works in an IT department and deals with servers, or at least it should be. What RAID 5 does is writes data across 2 drives similar to RAID 0, but then on a 3rd drive it will write parity information. What this does is allow the system to rebuild a drive in the event of a failure. You get increased performance and safety. One of the nice things about RAID 5 is that you can use as many drives as you can fit in the system and the drive controller can handle. The amount of storage space you have will be the total of all the drives minus 1 drives capacity. So with 3 100gb drives you would get 200gb of space.

RAID 1+0
The objective of this is to get the speed of RAID 0 and the safety of RAID 1. Essentially what you do is create a RAID 0 set of drives, and then mirror the set. This is why it requires 4 drives. This is the ideal setup for gaming since it maximizes performance and protection.

It is only recently that you see RAID 5 and RAID 1+0 options on the embedded RAID controllers on PC desktop systems. Historically the logic required to control such a system ended up with controllers that were simply too expensive for manufacturers to include on the mobo. This brings us to the most important part of your RAID setup, the controller.

Most people use the controller that is on their motherboard, why? 'Cause RAID controllers are damn expensive. But there is a reason for that, they do a lot of work. If you were to setup two identical systems, with one using an onboard controller and one using a good discrete RAID controller, the one with the add in card will win every time. Hands down. Good RAID controllers have extensive logic to optimize the read and write queues as well as cache memory.

Now don't get me wrong, this does not mean that the integrated RAID controllers suck, just that there are better ones out there. Sort of like on board audio.

I think that answers all of your questions but one: Stability. Simply put, your RAID array will be as stable as your hardware is. The odds of a drive failure are the same whether it is in an array or not. Whats the difference between having a 250gb drive fail that is in a RAID 0 array (giving 500gb of storage) vs a single 500gb drive fail? Either way you lose 500gb. Though with the array you only have to buy a 250gb drive to fix it.

As for 5400 RPM drives being okay, umm, not so much. While putting 2 5400 RPM drives in a RAID 0 will improve their overall performance, and it just might be better than a single 7200 RPM drive, it is not the route I would take, unless you have a bunch of 5400 RPM drive sitting around doing nothing.

I hope this helps.

I remember there being some ambiguity over the true meaning of the I in RAID...Just like the V in DVD

Just a little off topic question would i be able to have lets say 4x 500GB 7200RPM Drives doing raid 6(or would it be better to do raid 5?) . and then another drive lets say 150GB 10000 RPM without a problem? Never tried raid before and just started to look into it.

Edit: would they all need to be the same size to do a raid, and would i be able to add the 150gb to the raid and make sure it isn't used for the parity information?

Quote: Originally Posted by Gzim I remember there being some ambiguity over the true meaning of the I in RAID...Just like the V in DVD

As I recall, that would be independant(sp) vs inexpensive.

E

Quote: Originally Posted by deere Just a little off topic question would i be able to have lets say 4x 500GB 7200RPM Drives doing raid 6(or would it be better to do raid 5?) . and then another drive lets say 150GB 10000 RPM without a problem? Never tried raid before and just started to look into it. Edit: would they all need to be the same size to do a raid, and would i be able to add the 150gb to the raid and make sure it isn't used for the parity information?

You could do the 4 drives in RAID 6 or 5 and the 150 on it's own as long as your controller supports that. The drives do not have to be the same size to do RAID, however, the system will only use the amount of space on each drive that is common to the smallest drive. For example, an array with 3 500gb drives and 1 250bg drives would only use 250gb of each of the 500gb drives.

Quote: Originally Posted by Fred_G As I recall, that would be independant(sp) vs inexpensive. E

Fred, I have heard both I words used, though I think originally it was inexpensive. But I could be wrong. Either way works for me.

And the Wikipedia entry has both in it, so I guess we are both correct. Woo-hoo, everyone wins!

Lowest common denominator.

The reason the inexpensive vs independant debate hit.

Inexpensive was originally used for the fact that it was an easy way to buy a pile of cheap disks and make an array of sort. Hard drive manufactures got mad about this, like the consumer was calling their drives cheap. So they un-officially re-named it to Independant.

Its a funny story, but I like RAID, just hope no one raids my house to confinscate my raid, and raids the data.


EDIT:

Quote: Originally Posted by abyssling Lowest common denominator.

Wow a good ole pimp incarnated, where yea been?

Quote: Originally Posted by Gzim I remember there being some ambiguity over the true meaning of the I in RAID...Just like the V in DVD

Originally it was "inexpensive" because 1Gb of storage by way of four 250Mb drives was cheaper than one 1Gb drive back in the day.

Now it's "independent" because 2x250Gb drives cost more than 1 500Gb.

Hard Drive Fact:No matter the size, a hard drive only has two states: new and full.

Quote: Originally Posted by Cyno01 Hard Drive Fact:No matter the size, a hard drive only has two states: new and full.

:h aha:
Ain't that the truth. And the time it takes to go from one state to the other is directly proportional to your download speed.

Thanks guys that sheded alot of light on my concepts of hard drives. I asked about the 5400 rpm drives becase I'm getting my dumpy alienware laptop replaced and was thinking of doing a raid 0 with a pair of 5400 250 Gig drives in it, but I guess I'll need to re think that.

Quote: Hard Drive Fact:No matter the size, a hard drive only has two states: new and full.

Ain't it the Truth thats why I just got 3 500 GB seagates. Thats what this was all about. I had the guys a best buy telling me "3 7200rpm hard drives = 21,600rpm" and I was pretty sure they where full of crap. So I was trying to figure out the truth about thease RAIDs, looking to RAID those 3 the best possible way.

Thanks again everybody.