TechSpot

Anyone explain RAID?

By henrychieng
Mar 12, 2002
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  1. dmill89

    dmill89 TS Guru Posts: 737

    RAID=Redundent Array of Inexpensive Disks
    RAID 0, combines areas of free space from up to 32 multiple hard disks into one logical volume. This volume optimizes performance by allowing data to be written to all the disks at the same rate. This volume is not fault-tolerant as well so if one disk in the volume fails, then all the data is lost
    RAID 1 Disk duplexing eliminates the single point of failure that exists in disk mirroring. This is done by adding another disk controller and configuring the RAID system to duplicate data on disk drives that are attached to two different disk controllers. There is generally no significant performance difference between disk mirroring and disk duplexing. The user is just adding further redundancy in the form of a second controller. The overhead of RAID 1 duplexing is 50 percent.
    RAID 5 requires a minimum of three disk drives to implement. The disk drives that comprise a RAID 5 solution are often referred to as a RAID 5 array. The failure of a single disk drive does not cause the network server to fail. The missing information that was on the failed disk can be recreated quickly using the information on the remaining disks. The failed disk drive should be replaced as quickly as possible. RAID 5 cannot survive the failure of a second disk drive after one disk drive has failed. Because of this fact, some RAID systems allow for the configuration of a "hot spare" disk drive in the RAID system. A hot spare disk drive is powered up and running, but it contains no data. It is just waiting for a drive in the disk array to fail so that it can be used.
    RAID 0/1, which is sometimes called RAID 0+1 or RAID 10, involves mirroring or duplexing two RAID 0 arrays. This yields the fault tolerance of RAID 1 and the input/output speed of RAID 0.
     
  2. champmanfan

    champmanfan TS Member Posts: 59

    RAID Controller Over Motherboard's Controller?

    Would a SATA Raid Controller be better for getting a performance boost for my 2 SATA Maxtor DiamondMax10 HDs over the motherboards controller and boost the fps in games?

    In HD Tach I get 139Mbps but is it possible to reach the quoted SATA speeds of 150mbps?

    My motherboard is MSI MS-6741 v1.0 and the BIOS is American Megatrends Inc. v.07.00T (04/02/01). I'm reluctant to update my BIOS because i've been told by 'experts' that it shouldn't be done unless there is already a problem with it. For the people that have updated their BIOS, how many times have you done it on the same motherboard?

    I have updated my 2 DVD NEC 3520 drives to unlock the rip speeds, so I do have 'some' flashing experience.
     
  3. alphnumeric

    alphnumeric TS Rookie Posts: 209

    SATA is faster than PATA (IDE) so SATA RAID should be faster than the IDE RAID. SATA is 150 mbps and IDE is only 100 or 133 mbps. You will only hit 150 mbps in bursts. I've flashed my current motherboard several times. If your motherboard has boot block or dual BIOS you have a safety net in case the flash goes bad. The second backup BIOS will take over and let you recover and try the flash again. If you know what your doing the only danger is a power failure or power bump in the middle of the flash.
     
  4. Tedster

    Tedster Techspot old timer..... Posts: 10,074   +13

    just did my first IDE raid 0 today when I overhauled my system. I kept getting blue screen errors on a driver so it got so annoying I decided to reformat my hard disks. I had fogotten my motherboard supports RAID so I thought I would try it. It was a litle tricky because my floppy with the raid drivers was flakey and I had to do a traditional install, copy my floppy to a good disk, then reinstall with BIOS and driver changes to force a RAID 0. overall, the throughput increase isn't phenominal, but its somewhat of an improvement - perhaps 15 to 20% gain in speed.
     
  5. champmanfan

    champmanfan TS Member Posts: 59

    RAID Install

    Tedster - good to hear you managed to successfully setup your HD to RAID because when I got my two Maxtor DiamondMax10 SATA HDs, I had to download over 120Mb of drivers & stuff (MaxBlast 4 For Windows) to enable RAID rather than the typical setup. The drives were bought as OEM from Komplett - they're pretty cheap for most stuff :)

    I bought the drives, intending to use them for performance gaming and using Adobe Premiere. At the time of buying, I found the load times of levels in Half-Life 2 a pain where it would sometimes take up to a minute to load, it now loads in about 15-20 seconds, very reasonable. Having plenty of RAM - 1GB 2700DDR in my case - stops it caching to the HD and slowing my games down.

    I'm saving up gradually now for a new system based on dual-core (or tri-core if i'm slow on the take-up) and getting the newer SATAII drives. I haven't seen any reviews of benchmarks with a couple of these drives in RAID-0 - if anyone has seen some then please post the results here - so i can see if there is much benefit to be made or I could be wasting money. Thanx :)
     
  6. lukeyu

    lukeyu TS Rookie Posts: 70

    Level 0 -- Striped Disk Array without Fault Tolerance: Provides data striping (spreading out blocks of each file across multiple disk drives) but no redundancy. This improves performance but does not deliver fault tolerance. If one drive fails then all data in the array is lost.

    Level 1 -- Mirroring and Duplexing: Provides disk mirroring. Level 1 provides twice the read transaction rate of single disks and the same write transaction rate as single disks.

    Level 2 -- Error-Correcting Coding: Not a typical implementation and rarely used, Level 2 stripes data at the bit level rather than the block level.

    Level 3 -- Bit-Interleaved Parity: Provides byte-level striping with a dedicated parity disk. Level 3, which cannot service simultaneous multiple requests, also is rarely used.

    Level 4 -- Dedicated Parity Drive: A commonly used implementation of RAID, Level 4 provides block-level striping (like Level 0) with a parity disk. If a data disk fails, the parity data is used to create a replacement disk. A disadvantage to Level 4 is that the parity disk can create write bottlenecks.

    Level 5 -- Block Interleaved Distributed Parity: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance. Level 5 is one of the most popular implementations of RAID.

    Level 6 -- Independent Data Disks with Double Parity: Provides block-level striping with parity data distributed across all disks.

    Level 0+1 -- A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.

    Level 10 -- A Stripe of Mirrors: Not one of the original RAID levels, multiple RAID 1 mirrors are created, and a RAID 0 stripe is created over these.

    Level 7 -- A trademark of Storage Computer Corporation that adds caching to Levels 3 or 4.

    RAID S -- EMC Corporation's proprietary striped parity RAID system used in its Symmetrix storage systems.
     
  7. s3xynanigoat

    s3xynanigoat TS Rookie Posts: 141

    IMO, RAID 0 is worth it for anyone who considers themselves a gamer. I have not done benchmarks and test and what not, but I have seen the effects of my current set up. Prior to adding raid 0 I had the following set up.

    IC7-G Socket 478 Mobo
    Prescott 3.0e
    9800pro 128mb
    512 mb RAM
    Maxtor 250 gig SATA

    After looking at my systems inability to keep up with load times and the constant lag I was getting in games I dropped 268 dollars on 2 gigs of Corsair-XMS RAM. This cut my lag time upon entering Ogrimmar in the World of Warcraft game down form 25 seconds to maybe 7 seconds. I then dropped 203 dollars on two 36gb Raptors, which I promptly put in a RAID 0 array. This has taken me from the 7 seconds of lag I had down to 0. I can now do anything in that game and not experience even a hiccup. For you guys who play WoW you will understand what I am saying here as now even Alterac Valley has no lag.

    If I were someone considering RAID 0 I would absolutely get the 36gb Raptors, RAID 0 would make these approx 74 gigs total. The reason being is RAID 0 is not fault tolerant, so you wouldn't want massive amounts of downloaded information on these drives. Instead you put your games and O/s on here and get a larger, slower/cheaper drive, that will hold all your downloaded things.

    RAID 0 can be a bear to set up if you don't have documentaion. My motherboard is not supported anymore but I was able to get a copy of the motherboard manual in *.PDF form off the intraweb. Unfortunatelly the manual didn't have much to say about RAID, just a few blurbs. After a little fumbling through the BIOS and a few bad driver downloads I had my RAID 0 up and running ( each bad driver download meant a new install of Windows for me as I only had the one machine I was installing RAID to). I could not be happier with the end product.
     
  8. iNoob

    iNoob TS Rookie Posts: 91

    I currently have a Seagate Barracuda 7200.7 160GB @1.5Gb/s hard drive and I'm thinking about setting up a raid 0. My question is, do I have to get another 7200.7 @ 1.5Gb/s for the raid setup to work or can I get the newer 7200.9 @ 3.0Gb/s and still have it work properly?
     
  9. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    Here's a question - if you have 4 hard drives, and want extra performance and redundancy, and can't do RAID 5...

    a)Level 0+1 -- A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.

    b)Level 10 -- A Stripe of Mirrors: Not one of the original RAID levels, multiple RAID 1 mirrors are created, and a RAID 0 stripe is created over these.

    Which would be best?
     
  10. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    You can mix the two different disks. But both will operate at the speed of the slowest disk, of course. Also, both can be different sizes, but the size of the array will be 2 x the size of the smallest disk.
     
  11. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    I have thought about it, and I think the best idea would be:

    a)Level 0+1 -- A Mirror of Stripes: Not one of the original RAID levels, two RAID 0 stripes are created, and a RAID 1 mirror is created over them. Used for both replicating and sharing data among disks.
     
     
  12. s3xynanigoat

    s3xynanigoat TS Rookie Posts: 141

    Agreed, I would choose option ( A: ) as well. Sorry for tardiness.
     
  13. tone45

    tone45 TS Rookie

    xp keeps rebooting with sata installed

    Hi Guy's..... :) Need help with my computer, I have a 40gig ide hdd and a 80gig sata which connects via pci card. The 40 has win xp sp 2 on and the 80 is storage, I reformatted my 40 and pulled the sata out at the same time. Now I can not get my 80 to work again, the comp boots up to the xp flash screen and then reboots again. I pull the cable off the sata drive and it boots up fine. I could do with some help if there is any one out there.......Starting to go up the wall :bounce:
     
  14. cfitzarl

    cfitzarl TechSpot Chancellor Posts: 2,520   +9

    What is RAID? I know it has something to do with a second hard drive, and that it is on my motherboard.
     
  15. alphnumeric

    alphnumeric TS Rookie Posts: 209

  16. lawrencej

    lawrencej TS Rookie

    Raid 1 and Raid 5 installation

    Hi,
    I would appreciated if any one could explain step by step, how to install Raid 1 and Raid 5 on an IBM server ? I have a new IBM 346 xseries server with 2 x 73.4 GB SCSI and 3 x 140 GB Scsi Drives. There is one Raid controller 7k card to be installed. I would like to install Raid 1 on the two 73.4 Disks and Raid 5 on the three 140 GB disks. I intend to install Windows 2003 OS on the 73.4 Hard disks and Oracle database on 140 GB Disks. Starting from very begining can anyone explain how to proceed. After installing Raid 1 and RAid 5, how do I test whether the installations are correct. I have not installed RAIDs so far and it is new to me.

    Joseph
    lawrencej@hotmail.com
     
  17. BBTex

    BBTex TS Rookie

    Hello all. This is my first (but hopefully not my last) post on this site. I just wanted to say, that although I am not the most experienced person on this subject, I have used RAID in the past, and in all honesty, it was nothing but trouble, especiellay when my system crashed, and I tried to format and reinstall the OS. I would recommend not doing it unless absolutely necessary.
     
  18. codez13579

    codez13579 TS Rookie Posts: 68

    I would like to ask 3 questions regarding raid 0+1:

    1) Currently, I am running XP on a WD 60gb HDD 7200rpm. I bought a new WD 60gb HDD 7200rpm. Can i install raid 0+1 without reformatting the XP WD?

    2) I also have a Seagate 150GB HDD for storage. If I install raid 0+1 on my two WD 20GB HDD 7200rpm can i run games, music and programs off my 150GD Seagate?

    3) How do I install Raid 0+1?


    Sys:
    Asus Intel P4C800-E Deluxe
    Intel Pentium 4 @ 3.0GHZ
    Ndivia Geforce FX5200 128MB DDR
    Kingmax 2x512MD SDRAM DDR 400
     
  19. Malganis

    Malganis TS Rookie Posts: 23

    Sorry for the bump, but I have one Hitachi Deskstar 7K250 now, but when I just put an extra one in and format that, What is the default RAID setup? RAID 1? If so.. what is the advantage of putting it in RAID 0? Can I merge the two together aswell? To make 1 HD of 500GB with two of 250GB?

    I don't think I understand what RAID is for yet. Somebody care to explain? :)
     
  20. alphnumeric

    alphnumeric TS Rookie Posts: 209

    Did you read all the posts in this thread? There are many links to info to explain RAID in this thread. :)
     
  21. Malganis

    Malganis TS Rookie Posts: 23

    Oh sorry, I will do that tomorrow. Thanks. Must've missed it 'cause I'm too tired right now. :p

    Edit:

    Ok, so I've read the entire thread. This article was most helpfull.

    But if I setup 2 drives in RAID 0, If 1 fails.. both fail. But how does a drive fail? I have absolutely never crashed a HD and destroyed all of it's content. So I think it's pretty safe to buy an extra Hitachi Deskstar 7K250, since the prices are lower then ever. About 20 euro's less then what I bought my first one for. But I also need a RAID controller right? How are they configured? Software? Or do they have a switch on them?

    What is a good RAID Controller? I didn't see a post saying anything about that.
     
  22. tjyaz27

    tjyaz27 TS Rookie

    Could not initialize storage

    Hey i dont think this error has much to do with RAID but recently when i have been trying to download a patch for world ofwarcraft it says "Could not initialize storage. "You may not have permission to write to the destination path." Does anyone know how to fix this isssue? I have had the game for a while and this is the only time the error has come up. I tried rebooting my cpu, running symantec, spybot, and giving myself administrator but this error stilloccurs.
     
  23. Sasquatch

    Sasquatch TS Rookie

    OK, I've read the whole thread and many of the linked articles as well as links from those articles. I now have a decent grasp on the basics of RAID. What I have yet to see anywhere is how it's significantly better than just using multiple drives and storing different things on different drives. Why not use a smaller drive to boot and run the basic desktop apps, then use other big drives as dedicated storage for various intensive programs? Seems this would provide the same benefits as RAID with a lot fewer hassles.

    For example, I could run my desktop with all it's crappy little games and stuff off a 30-50GB drive, then have a dedicated 750GB drive for storing files for my 3D animation program, another 150GB drive for music, maybe another 300GB for photos. Wouldn't that be simpler? The smaller drives could be easily backed up on CDs which would only need updated when you changed the HD contents.
     
  24. alphnumeric

    alphnumeric TS Rookie Posts: 209

    Raid 0 is supposed to give you a performance boost. You are reading from more than one drive at a time and data retrieval is faster. As you noted though if one of the two drives in the set dies all data is lost. Hard drives don't last forever and will eventually fail. Actually all you need is for windows to blue screen on you and you could loose the whole array and have to rebuild it.
     
  25. alphnumeric

    alphnumeric TS Rookie Posts: 209

    I tried running Raid 0 for a while and didn't notice any great increase in speed. After rebuilding the array a couple of times due to windows glitches the novelty wore off. I just store things on different drives like you mentioned.
     


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