TechSpot

Anyone explain RAID?

By henrychieng
Mar 12, 2002
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  1. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Posts: 4,916   +9

    Is RAID01 same as RAID10?
     
  2. Vehementi

    Vehementi TechSpot Paladin Posts: 3,199

    Probably Mict. Seems like it.

    May be different though, like switching around the drive responsibilities in RAID10 or something.
     
  3. bedlam_4

    bedlam_4 TS Rookie Posts: 182

    Mic I think its either raid 0+1 (0/1) or just raid 10. Reference Mic's explanation of raid 0/5 or 50. Semantics.

    After reading Phantasm's above post I called Falcon Northwest. They configured a machine for benchmark tests and sent it to Computer Gaming World Magazine. The rig was the P4 Canterwood w/ raid 10 (0+1). Raid 0 was set up with the two smallish 36Gig 10,000rpm wetern digital drives and a third 120Gig (raid 1 array) HD for storage.

    Awesome rig. You can read all about it in this months issue.
     
  4. cromrell

    cromrell TS Rookie Posts: 52

    I think I'll quickly add my support for RAID on servers.
    theory in action:

    DELL PowerEdge 1400
    2@ 18GB SCSI RAID1 (mirror) w/ 2 partitons (both mirrored)
    Server acting as Primary Domain Controler, File Server, etc.

    about a year ago, our DELL NT server completely crashed and I was up most of the evening with support, trying to get the thing back up w/o re-installing or complete restore from backup tape.
    After all the DELL hardware checks were clean, and it appeared to be a problem with the NT OS, I finally thought to try and startup on the 2nd disc (mirrored drive).
    It came up great & I was able to verify that the mirror was 'current', and then I justed re-mirrored the now idle drive to the now-active drive (which used to be the mirror).
    I've since read some things that mirroring your OS drive isn't a great practice, but it sure worked for me.
    -C
     
  5. Acidis

    Acidis TS Rookie Posts: 20

    I am confused by one of the aspects of setting up RAID 1. I have a PC-DL Deluxe motherboard from ASUS. It has a built-in Promise controller with 2 SATA and 1 ATA connectors for that controller.

    The manual for the board is not clear on how many drives need to be connected where. Here is the quote:

    "Connect the HDD cables. These connection options are available for creating a RAID 0 or RAID 1 array:

    a) Connect two Parallel ATA HDDs to PRI_RAID connector and one Serial ATA HDD to either one of the two Serial ATA connectors, using separate parallel ATA or serial ATA cables.

    b) Connect one Serial ATA HDD to each Serial ATA connector, using separate serial ATA cables.
    "


    Option a) seems to imply a connection of 3 drives, which does not make any sense.

    Can I connect two hard drives to the ATA (PRI_RAID) connector (master and slave) and set it up as RAID 1?
     
  6. Mictlantecuhtli

    Mictlantecuhtli TS Evangelist Posts: 4,916   +9

    Depends on motherboard's RAID options, naturally. Performance would be better if you used separate controllers though. RAID 1 uses two drives, not three, so I have no idea what Asus is talking about..
     
  7. alphnumeric

    alphnumeric TS Rookie Posts: 209

    Each extra IDE channel (raid0 raid1) can handle two IDE devices, hard drives, cr-rom etc. If your not using them set up as raid you can put what ever you like on them. If you do use raid then you have to put your drives in a set pattern. One drive as Pri on one raid channel and the other as Pri on the other raid channel for say raid 0. You can then put your cd-rom and any extra had drives on you regular IDE channels. That's the way I see it.
     
  8. alphnumeric

    alphnumeric TS Rookie Posts: 209

    I just ordered a PCI raid controller from Tiger direct. It's ata133 and so are my two 80 gig Maxtor's. Right now I have them running on my ATA100 mobo controller. I'll run HDtach before and after and post the results after Christmas. My plan is to use Raid 0 for the extra speed.
    Here's some info I found too add to the mix
    Raid level
     
  9. alphnumeric

    alphnumeric TS Rookie Posts: 209

    OK my raid 0 is up and running.
    I have two identical Maxtor 80 gig 7200 rpm drives 2m cache.
    Before raid HDTach showed this for speed
    Random access time was 14.2 ms
    Read Burst speed 36 megabytes per sec,
    Read speed max 61744 kilobytes per sec, min 3457 kilobytes per second
    Average was 473443 kilobytes per second. CPU utilization was 11.7. My second drive was almost the same.
    with raid 0
    Random access time was 14.4 ms
    Read Burst speed 36 megabytes per sec,
    Read speed max 59705 kilobytes per sec, min 52120 kilobytes per second
    Average was 42756 kilobytes per second. CPU utilization was 14.6
    What I noticed running HDtach is as the hard-drive position moved to-wards the higher values the read speed dropped for non raid, but remained the same for the raid 0. The read speed was the same anywhere on the drive(s). I don't know if it factors into it but in both cases the drives were partitioned into 4 partitions. I don't know why the average is so low with Raid?
    Maybe HDTach wasn't a good choice to bench mark.
     
  10. Vehementi

    Vehementi TechSpot Paladin Posts: 3,199

    I set up RAID0 with 2 120GB Western Digital Special Editions (7200RPM, 8MB cache) yesterday.

    HDTach said:
    Random Access Time - 13.1ms
    Read Burst Speed - 74.2mbps
    Read speed max - 65129kps
    Read speed min - 25198kps
    Avg. - 59245kps

    But still, my single 74GB Raptor (10,000RPM, 8MB cache, SATA) spanked it. Raptor HDTach is here.

    Not what I expected, but it's still incredibly fast anyway.
     
  11. Glenville

    Glenville TS Rookie

    Hmm ... always wanted to know a liitle more about RAID ...Never really bothered me in the past ... you guys have anwered a few questions....

    A Good flat in Stockton on Tees went for £12,000 recently...Heh!
     
     
  12. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    Its a great upgrade to your machine to get RAID, particularly if you are into video capture or demand high grade disk performance or are just completely geeky like me.

    Just start with a 2 disk RAID 0 stripe. This means that you combine the disk space into one volume and double its speed. The total size of the array is the size of the smallest disk times 2.

    Of course, if one disk fails, then you loose everything, so therefore your chances of loosing all data has just increased by 100 per cent.


    You can also build mirrors which make an automatic copy of one hard drive onto another. You loose 50% of space but now your chances of loosing everything have greatly diminished.

    The total size of the array is the size of the smallest disk times 2.

    You get the picture.

    Lots of the more kick *** motherboards even available in high street stores have RAID controllers built onto them, but you can just get a RAID controller card as well, which is just a regular PCI card.

    Its nice to use disks of the same model and make as well, if possible.
     
  13. alphnumeric

    alphnumeric TS Rookie Posts: 209

    You won't get double your speed by using RAID 0, it's more like a 20-50% increase. :)
     
  14. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    Well, to be honest, its hard to say exactly what it is. I just wanted to illustrate the concept. Its certainly a hell of a lot better, but it that way.
     
  15. GREC

    GREC TS Rookie

    Performance

    Well guys, I've always worked with RAID arrays at work but never really thought that I would (could afford) want one at home since SCSI disks are too expensive and IDE's just don't give you that much performance

    until...

    Western Digital released their new hot RAPTOR line of drives running at 10.000 rpm, SATA 150. (No, I don't work for WD, not even close). I searched the internet about these drives and only found positive responses, the first drive was a 36 gb., which just isn't big enough for today's standards.

    Anyhow, I ordered 2 of the big brothers (74 GB) and now have them in a RAID - 2 x 74 = 148 (in reality only 168 GB). They are just nice nice nice nice, I want to explain one thing here, your performance improvement in a RAID yeah, could be something between 20% to 50%... but if you get a Raptor, bear with me, and set it up as your system drive, Windows loads faster, all your programs load faster because of the improved access time, I do some heavy programming and compiling and also play games, and can really feel the difference in anything I do.

    Burn me for what I write if you please but before, go and read about these drives. (Ahh ok, they cost a little more per GB, but who needs 250 Gb space? anyways, if you do, set the Raptors as your System drive and install all your heavy applications, games etc. there, and use an inexpensive 250 Gb for your files, porns, etc.)

    Cheers boyz :)
     
  16. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    Re: Performance

    Me! And a lot of others too, I'll bet.

    I already have a plan to make a RAID 0 Stripe from 4 x 250GB SATA HDD to make 1 TB disk space volume. No more piles of CDs everywhere - just keep everything on the one data server.

    That could go into my current Pentium 4 machine, but I think its more likely I'll push it back until I build the kick-*** next gen machine I am building next year or the year after for longhorn.
     
  17. GREC

    GREC TS Rookie

    1 TB is pretty cool, as you write, no more piles of CD's (DVD's in my case), no more moving around of files so you can make space for the latest games requirements etc but I think you are forgetting one very important detail about RAID 0, which is:

    No fault tolerance
    if 1 of your 250 GB SATA HDD decides to go to ETHER space (DIE) then it will result in loss of ALL DATA (1 TB!!!).

    I hope you have a good backup strategy in case this should occur.

    Good luck with your kick *** machine!
     
  18. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    OH no, I had not forgotten.

    Actually, I am investigating the possbility of a RAID 5 SATA controller. These are not cheap, especially if they support hot swapping HDD drives. But its possible.
     
  19. alphnumeric

    alphnumeric TS Rookie Posts: 209

    Lets see 1 tb raid 0, backup would be a huge pile of cd's.:eek:


















    j/k I couldn't resist ;)
     
  20. Rick

    Rick TechSpot Staff Posts: 6,305   +52 Staff Member

    Out of curiosity, is RAID 5 100% fault tolerant? (with parity drive failure aside ;) ..)

    I am not sure I understand how it works totally, but I cannot see how it would be very reliable to rebuild your data with just parity information.

    I'm assuming something like RAID 1 or 10 would be more secure, correct?
     
  21. Phantasm66

    Phantasm66 TS Rookie Posts: 6,504   +6

    Well, so long as you never loose more than one HDD at a time, all you have to do is replace that HDD with another one and the data will be regenerated.

    This is a lot cooler than RAID 0, but that's why RAID 5 controller cards are a lot more expensive.

    Today I just bought 2 x 160GB Maxtor SATA HDD which I am going to RAID 0 into one array.
     
  22. AdrianScotter

    AdrianScotter TS Rookie Posts: 52

  23. alphnumeric

    alphnumeric TS Rookie Posts: 209

    Well, I have dumped my RAID 0 setup for a more traditional master slave setup. I didn't notice any speed benefit and didn't need one 160 gig drive.:eek: Now I can use true image to backup my main drive to my slave. Now I can go a clean install from my image in about 10 mins, instead of 10 hours.;)
     
  24. Jared

    Jared TS Rookie

    Ok so, before I even start to read all of these "Raid" post, I just need to understand the very basics of Raiding, as in how it 100% works and what not. Does anyone know any good sites that explain the basics of it? I've googled a bit, but that's what brought me here, and to a few other sites that jump a little further ahead than my likings. Thanks.
     
  25. MESS

    MESS TS Rookie

    I think I kind of agree with Jared could you guys and gals, explain it kind of like this "Raid for Dummies". I have heard about the benefits of this that and the other, the question is if someone is new to the concept is there a website or someone here that could really explain it in it's simplest form. Which type of Raid, Raid 0, 0/1, 1

    Processor: AMD Athlon 64 3400+ Socket 939 CPU (CP2-A64-34009 C )

    Motherboard: Asus A8V Deluxe Via K8T800 Pro Socket 939 Motherbo (A455-2110 )

    Hard DrivesX2: WD Caviar 120GB Serial ATA HD 7200/8MB/S-ATA-150 (TSD-120JD TSR )

    Hard drives are identical

    Remaining Hardware is listed in my profile.
     


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