Raid Setups......need INPUT....

ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

Hello guys, my name is ToggleHead and i am interested in learning about Raid setups.

ok i'll knock that off......

I am new to to the world of HDD technology (sorta) and i am curious to have someone help me out. I have had a Raid controller in my machine before, but it was simply for more IDE ports.

What is striping?
And im guessing that mirroring is writing and reading two drives that are identical as in Raid 0? Why does raid 0 have a higher data loss ratio compared to raid 1.

And my friend just got an old server setup in Raid 5 and i have NO idea whats going on......lol
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Yoshida · UberTweaker Joined: 24 Dec 2003 Posts: 1219

Im not all knowledageble about raid setup's either, but I did a little research for ya @ www.whatis.com (godly computer terms website)

Hopefully this will answer all your raid questions th,

RAID (redundant array of independent disks; originally redundant array of inexpensive disks) is a way of storing the same data in different places (thus, redundantly) on multiple hard disks. By placing data on multiple disks, I/O operations can overlap in a balanced way, improving performance. Since multiple disks increases the mean time between failure (MTBF), storing data redundantly also increases fault-tolerance.
A RAID appears to the operating system to be a single logical hard disk. RAID employs the technique of striping, which involves partitioning each drive's storage space into units ranging from a sector (512 bytes) up to several megabytes. The stripes of all the disks are interleaved and addressed in order.

In a single-user system where large records, such as medical or other scientific images, are stored, the stripes are typically set up to be small (perhaps 512 bytes) so that a single record spans all disks and can be accessed quickly by reading all disks at the same time.

In a multi-user system, better performance requires establishing a stripe wide enough to hold the typical or maximum size record. This allows overlapped disk I/O across drives.

There are at least nine types of RAID plus a non-redundant array (RAID-0):

RAID-0. This technique has striping but no redundancy of data. It offers the best performance but no fault-tolerance.
RAID-1. This type is also known as disk mirroring and consists of at least two drives that duplicate the storage of data. There is no striping. Read performance is improved since either disk can be read at the same time. Write performance is the same as for single disk storage. RAID-1 provides the best performance and the best fault-tolerance in a multi-user system.
RAID-2. This type uses striping across disks with some disks storing error checking and correcting (ECC) information. It has no advantage over RAID-3.
RAID-3. This type uses striping and dedicates one drive to storing parity information. The embedded error checking (ECC) information is used to detect errors. Data recovery is accomplished by calculating the exclusive OR (XOR) of the information recorded on the other drives. Since an I/O operation addresses all drives at the same time, RAID-3 cannot overlap I/O. For this reason, RAID-3 is best for single-user systems with long record applications.
RAID-4. This type uses large stripes, which means you can read records from any single drive. This allows you to take advantage of overlapped I/O for read operations. Since all write operations have to update the parity drive, no I/O overlapping is possible. RAID-4 offers no advantage over RAID-5.
RAID-5. This type includes a rotating parity array, thus addressing the write limitation in RAID-4. Thus, all read and write operations can be overlapped. RAID-5 stores parity information but not redundant data (but parity information can be used to reconstruct data). RAID-5 requires at least three and usually five disks for the array. It's best for multi-user systems in which performance is not critical or which do few write operations.
RAID-6. This type is similar to RAID-5 but includes a second parity scheme that is distributed across different drives and thus offers extremely high fault- and drive-failure tolerance. There are few or no commercial examples currently.
RAID-7. This type includes a real-time embedded operating system as a controller, caching via a high-speed bus, and other characteristics of a stand-alone computer. One vendor offers this system.
RAID-10. This type offers an array of stripes in which each stripe is a RAID-1 array of drives. This offers higher performance than RAID-1 but at much higher cost.
RAID-53. This type offers an array of stripes in which each stripe is a RAID-3 array of disks. This offers higher performance than RAID-3 but at much higher cost.

racing87stang · Posted: Fri Jul 30, 2004 10:10 am Post subject:

WHUH!!! i got lost after RAID
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ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

WOW...thanks yosh.....for that website too......great info......i'm sure i'll have morequestions after reasearch......thanks again.......perhaps a sticky consideration on this one
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2old2care · Posted: Fri Jul 30, 2004 11:09 am Post subject:

TH...go to Adaptec's website, and read their whitepapers. You'll learn a ton about HDD's electronic technology and history.
Also good if you are an insomniac.
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Josh · Posted: Fri Jul 30, 2004 11:50 am Post subject:

I'm lost

Very informative post yoshida, that could also be something added to the possible new section, hey?

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Silicon Skum · Posted: Fri Jul 30, 2004 2:29 pm Post subject:

I think that post about covers anything (and more) than you'll ever need to know about RAID. Good find!

If you want to know about RAID first hand, I would go out and buy in 2 or 4 identical drives, they don't have to be big, new or expensive, just as long as they match or are close enough to each other specs. you do'nt need a raid controller if you have an NT based OS ( win 2K or XP), the downside to using software based raid is that you only have raid when you boot into windows. in most instances you would set up software raid on 2 drives, a third would be your system boot drive (pri master IDE, OS only on this drive). RAID 5 offers the best performace and fault tolerance, but it does have draw backs too. think what you would like to do with your system, you may not need the high fault tollerance, so striping would be the best choise as this gives you faster access to the drive(s). to set up RAID, use the system "manager" to access the disk properties, if you get stuck, check windows help, in does clear a few points up. you will need Administrative rights on the computer to change the disk setup.

If you are thinking about using RAID to speed up your system, I would use a SCSI RAID controller card and 4 SCSI hard disks. this way you have RAID access when booting winows (should load faster) and if you use any Dos based utilities, linux etc. you can still access the drive's contents. If you go SCSI route, you can have 4 IDE devices on your system, and as many SCSI devices as is supported by your card (typically 7-9). Dont forget that SCSI MUST be "Terminated" at the end of the cable. most SCSI devices should have this built in. Only the devices on either end of the cable should be terminated e.g SCI card and the last drive on the cable.

Incase anyone asks - SCSI = Small Computer System Interface.

The parts are not really that different in cost compared to IDE, can be faster and leave the CPU free, though they are not as easy to find, most computer shops never get anyone in who ever heard of SCSI.

SS

ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

LOL.....im a mac user as well....although not as well versed as PC......but i am quite familiar with scsi.....thatnks SS

Heres the new question........i game, but not much........im an audio editor and i create A LOT of my own music....im looking for something that is REALLY data reliable....and speed up anything i can.......so you suggest raid 5 for this? (im guessing)

i have the below board, and im now running xp.......my board has onboard raid.......so now what is my first step, besides getting two identical drives?
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Silicon Skum · Posted: Fri Jul 30, 2004 2:48 pm Post subject:

[quote="i have the below board, and im now running xp.......my board has onboard raid.......so now what is my first step, besides getting two identical drives?[/quote]

UMMMM, get 2 identical drives! if you got on board raid, thats all you need. plug it in and set it up in the BIOS. then sit back and enjoy. setting up RAID is not that different from installing a new HD in your system. just try it and if you get stuck, post it here

Make sure you have the RAID drivers installed before seting anything up.

SS

ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

ok cool thanks......but again.......which option do you suppose is better for my needs?
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2old2care · Posted: Fri Jul 30, 2004 3:53 pm Post subject:

TH...that mobo only supports Raid0 and Raid1...(from the hardware side)

0=speed

1=data integrity

HD speed in gaming is not to important. But if you resample large pics or something that crunches large data (uses swap file extensively) RAID0 is a big help.

Software RAID is not highly recommended.
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ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

Right ok.....i get it.......thanks.......now...I cant have data loss at ALL........that is the MOST important......but i wouls like some improved performance when sampling larger files.......any suggestions?
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geekzta127 · Posted: Fri Jul 30, 2004 4:34 pm Post subject:

if you choose raid 1 you'd have to waste a HD for another...

2old2care · Posted: Fri Jul 30, 2004 4:46 pm Post subject:

(I'm back from my ISO meeting now....grumbles)

Define data loss.
No RAID system replaces a good back-up policy, and much of the r1 uses in networking of the past have gone, due to the quality of modern HDD's.
I ran r1 in a network situation for a while, but learned in modern times virii and other malwares just get on redundant drives. doubly ***ked.
So, my suggestion would be RAID0 and THE three rules.

1) Back-up

2) Back-up
and
3) Back-up
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geekzta127 · Posted: Fri Jul 30, 2004 4:47 pm Post subject:

agreed^^^^ i to have my system as raid0 and works great...

Josh · Posted: Fri Jul 30, 2004 5:21 pm Post subject:

Yeah, i understood raid 0- 1 before

Basically, Raid 1 acts as a mirror for the master to the slave, so if one goes, you got it all on the other and its always at the point you were last at.

I think im right in understanding that.
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2old2care · Posted: Fri Jul 30, 2004 5:29 pm Post subject:

Yes you do Josh, r1 is a mirror.
F one up, now U got 2 F'd up.
HDD failures are pretty rare now days. And when they do fail, they many times give you a warning.
Either way whip out your backup, and all is good.
Backup=good...No backup=bad $.02
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ToggleHead · TWEAKGURU Joined: 03 Mar 2004 Posts: 4360 Location: Jersey

thanks guys....i agree with the steady back up procedure and do it regularly........i'll get back to you when i take some new steps
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Josh · Posted: Fri Jul 30, 2004 5:55 pm Post subject:

I back up all my stuff to my old 40GB from now on, so all is good.

I use it as a sh!t storer!

I never knew about all those other RAID's tho, i thought there was only 0 and 1

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JayDubya · Posted: Fri Jul 30, 2004 6:41 pm Post subject:

I always think about it this way. If you don't have raid and you only have one drive and it f's up then your f'd up. It is really about the same odds when running raid vs running a single drive.
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Silicon Skum · Posted: Fri Jul 30, 2004 8:11 pm Post subject:

I agree with 2old, Raid is only applicable in a server environment. If you transfer large ammounts of data (loading BF etc) then it can have some benifit too. Generally you only add raid if you are going to build a high end system and don't want any lags in it.

Another point to make (saw it here somwhere) if your MB suports raid 0 and raid 1 then it *should* support R 5 which is just a combo of both. I got a couple of MBs that have this option.

In most every day situations, you don't need RAID, but you may find uses for it.

The only RAID systems I have set up, are my NT server and one high end overclocked AMD 3400 xp (32bit) which is used as a number cruncher.

You can always try it, it's not for everyone. RAID 5 is the best to get started with, 2 drives, both are mirrored and striped. best of all worlds.

Just my 1/ 50th of a £

SS

2old2care · Posted: Fri Jul 30, 2004 8:28 pm Post subject:

Finally home from work...so I'll post this thought...This is why I do RAID0...
and doing it SCSI puts the thoughput on the PCI bus...
and leaves the IDE for all the slow stuff, like full of optical drives, that you never use at the same time.
No real advantage to gaming, but she'll put the data down.

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JayDubya · Posted: Fri Jul 30, 2004 10:13 pm Post subject:

Finally letting some number speak for themselves. You don't happen to have anything to compare these to do you?
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2old2care · Posted: Fri Jul 30, 2004 11:06 pm Post subject:

[KoG]^weaZel · Posted: Sat Jul 31, 2004 10:29 am Post subject:

ok 2old ask and you shall receive! i have two 36 gig Raptors Raid0 on a WD sata raid card. I also have nero 6, I can install that when I get home tonight and I can run that benchie.
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