When you get your Xserve...

Discussion in 'Hardware Rumors' started by Toe, Jul 1, 2002.

?

What do you think of RAID on Xserves?

  1. RAID 0 and 1 are fine for me

    4 vote(s)
    14.8%
  2. I need at least 0+1

    4 vote(s)
    14.8%
  3. Anything less than 5 is for whimps

    9 vote(s)
    33.3%
  4. I'm going to cluster Xserves, so don't need RAID

    6 vote(s)
    22.2%
  5. What the heck is RAID?

    4 vote(s)
    14.8%
  1. Toe macrumors 65816

    Toe

    Joined:
    Mar 25, 2002
    #1
    If anyone has access to an Xserve, can you do one thing for me? Open the disk utility (or whatever controlls RAID setup now) and see if it supports anything other than RAID levels 0 and 1.

    Rumor has it the Xserve is supposed to support RAID 0+1 and RAID 5 and perhaps others (I'd really like to see 10). But perhaps this won't happen till OS X 10.2.

    Any clear info on this would be greatly appreciated!!

    Also, if you notice anything else in the Xserve that's different from regular OS X 10.1.5, that would be nice to know too. For example, Apple has said that an Xserve can boot from an Apple RAID, which can not be done with a regular Mac. Also Xserves can run headless. Anything else?

    TIA!
     
  2. Toe thread starter macrumors 65816

    Toe

    Joined:
    Mar 25, 2002
    #2
    Clustering?

    Well, I just posted that poll because I never tried it before, but it's interesting to note that a couple people seemed to indicate they'd prefer to cluster Xserves. So I'm just wondering, are y'all just clicking the coolest-sounding one, ro do y'all actuallyu know how to cluster Xserves?

    All I know right now is that Linda can do it, but she sounds expensive. ;)

    Are there ways to create clusters in the OS X Server tools?
     
  3. Catfish_Man macrumors 68030

    Catfish_Man

    Joined:
    Sep 13, 2001
    Location:
    Portland, OR
    #3
    Look up...

    ...the "appleseed" project. My friend and I (both 15 at the time) clustered his G4 and an old G3 powerbook in about 30 minutes (20 minutes of that was updating the OS on the pb).
     
  4. Toe thread starter macrumors 65816

    Toe

    Joined:
    Mar 25, 2002
  5. DavPeanut macrumors 6502

    Joined:
    Jun 5, 2002
    Location:
    Maryland
  6. Toe thread starter macrumors 65816

    Toe

    Joined:
    Mar 25, 2002
    #6
    A RAID is a Redundant Array of Inexpensive Disks. It entails using a hardware controller or a software driver to combine multiple hard drives together into one volume. There are different "levels" of RAIDs, which are really very different ways of combining disks.

    Level 0 is "striping," where all the drives are combined together into one big volume. The advantage is blistering speed. If the computer needs to write 100 MB to a 4-disk RAID, it only has to write 25MB to each disk, so it goes four times as fast. Add more disks and it gets faster. The killer benchmarks on the Xserve are based on a 4-disk Level 0 RAID. However, the BIG disadvantage of striping is that if any drive fails, all the data is lost. In the case of that 100 MB file, 25MB worth of it would be gone, and there's no way to recover it. Striping is most often used for video cvapture, where they ghave to suck down a ton of data as fast as possible. Once the data is captured, then it is moved to a more reliable drive.

    Level 1 is kinda the opposite. It is called mirroring. It only works with two drives, and the computer writes exactly the same information to each drive. There is no speed increase at all, but if one drive fails, NO data is lost at all. This provides extreme data security.

    Level 0+1 mixes the two methods, and only works with 4 drives, I think. It is a mirror of two stripes. Or a stripe of two mirrors. In any event, data gets striped over two mirrors, so with four drives, it goes twice as fast as one drive, but there is no chance of data being lost.

    Level 5 is the most popular one for big operations. It is more complex. It uses 3 or more drives (often up to 12, and even more). If n is the number of drives, it writes 1/(n-1) of the data to each drive except for one. So if there are 12 drives, it writes 1/11th of the data to each of 11 drives. The last drive is called a "parity drive," and it contains nothing but parity data. If one of those 11 drives fails, it can be rebuilt from the information on the other 11, plus the parity information. The L5 RAID can figure out what is missing by comparing the parity information to what information it still has. The advantages of L5 are extreme speed (with twelve drives, you supposedly go 11 times faster than one drive) and good protection against failure. The probems are the time it takes to rebuild a bad drive, and if two drives should happen to fail, all is lost. Also, the more drives you add the faster it is supposed to go, but the parity data gets more complex and there is more demand on the RAID controller, so it can start to slow down too.

    Level 10 is a lot like 0+1, but it has no limitation on the number of drives. It is a mirror of two big stripes. So with 12 drives, you would have two striped arrays of 6 drives, and those two stripes would mirror each other. The disadvantage is that it uses a lot of drives compared to the amount of storage space you get. But the advantage is that it is EXTREMELY difficult to ever lose any data with L10, and it is still very fast. Also, there is no time spent creating parity data. So with a 12-drive L10 RAID, you get 6-drives worth of data writing at a full 6 times faster than a normal drive, and there is very very little chance of losing any data.

    That's the brief overview. ;) Or at least my understanding of it. Do a search on "What is RAID" or "RAID levels explained" or something, and they'll probably give you better and more accurate info. Also, there are a lot of other levels of RAIDs, but from what I can tell, the vast majority only use the above levels.
     
  7. AlphaTech macrumors 601

    AlphaTech

    Joined:
    Oct 4, 2001
    Location:
    Natick, MA
    #7
    this is a RAID

    I went with RAID 0 on the game peecee at home, since I need speed more then data protection. If I loose the saved game files, it's not going to be the end of the world. If you use reliable drives, then you can safely get away with RAID 0 without the nagging worry in the back of your mind. If you are really concerned, use the four drives and go with the 0+1 RAID (same size/performace as a 2 drive RAID 0, but with the data protection of the mirror). There are not many retail cards that support RAID 5 (or higher) that are actually affordable. I don't want to spend more on the RAID card then the hard drive(s). Since I picked up a pair of 160GB drives for my RAID 0, that is not chump change. The RAID card was under $150, and is ATA133 (Promise TX2000 controller). I can always add another pair of drives later, to get even more storage (if I ever need to).
     
  8. Toe thread starter macrumors 65816

    Toe

    Joined:
    Mar 25, 2002
    #8
    RAID 0 and 1 are OK for home use, but on an Xserve, they just aren't going to cut it for most companies. And the thing is, OS X currently ONLY supports Levels 0 and 1 (not even 0+1). I'm talking about software RAID included in the OS.

    Yes, there are IDE RAID controllers, but these aren't server-grade. The thing Xserves need is at least 0+1 or preferably 5, and that's simply not available except in external RAID systems (can you say 5-figures?).

    I think OS 10.2 will support better levels. Also, SoftRAID is supposed to have a new version out soon. Also, this just came in on MacCentral: http://maccentral.macworld.com/news/0207/02.nxraid.php

    Anyway, the original question was: can an Xserve natively support higher than just 0 or 1 using Apple's RAID utility? Right now, or not till 10.2?
     
  9. neilt macrumors regular

    Joined:
    May 28, 2002
    Location:
    Phoenix, AZ
    #9
    The actual definition for RAID is Redundant Array of Independent Disks.

    There is nothing "Inexpensive" about more than 1 15,000rmp SCSI Drive! :D
     
  10. Nipsy macrumors 65816

    Nipsy

    Joined:
    Jan 19, 2002
    #10
    The 'actual' definition is as posted by Toe. Your definitinon is a bastardization (like y'all).

    RAID, the acronym, is from the days when a 2MB hard drive cost $2,000, and a 10mb hard drive cost $50,000. Therefore, it was cheaper to create a 10MB RAID volume (or JBOD volume) out of inexpensive 2MB disks.

    Nowadays, people often accept Redundant Array of Independent Disks as RAID, but if your aim is to correct someone else, you should be sure of your research.
     
  11. neilt macrumors regular

    Joined:
    May 28, 2002
    Location:
    Phoenix, AZ
    #11
    I did do a little research.... the screen snap below is from the help for OS X's Disk Utility, but after your response, I did some more and found that in 1987 when the original white paper was written at Berkley it did say inexpensive, but it has generally been changed to independent. So, you are correct that it has been modified. So , my apologies to Toe.

    and about y'all. The most respected professor at my university (a Oxford Ph.D.) maintained that y'all was a legitimate english contraction for you all. It also comes up with a very nice definition at Dictionary.com
    http://www.dictionary.com/search?q=y'all
     

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  12. cb911 macrumors 601

    cb911

    Joined:
    Mar 12, 2002
    Location:
    BrisVegas, Australia
  13. evildead macrumors 65816

    evildead

    Joined:
    Jun 18, 2001
    Location:
    WestCost, USA
    #13
    Re: Toe

    You can pick up a nice external RAID device from SUN for about $30k. I use Sun T3's a lot at work. They have their own UPS and will finnish anything on the stack and clear the buffer before shutting down, even if you pull the plug. They hold 9 73GB fibre drives. I use RAID 5 on all of my T3's and when used in a cluster I use RAID 0 accross multiple drives for extra redundancy.

    I think that there are other venders that are much cheeper. Sun has nice stuff, but it tends to be very pricy. I hear that Apple has a 2GB external harware RAID device comming by the end of the year. We will have to wait and see what kind of RAID that will suport.

    -evildead
     
  14. AlphaTech macrumors 601

    AlphaTech

    Joined:
    Oct 4, 2001
    Location:
    Natick, MA
    #14
    Re: Re: Toe

    Remember, RAID 0 is striping, not mirroring, no data reduncance, all for speed. :D

    I'm pretty sure that Apple's 3U RAID device will support up to 1.6TB of storage (14 120GB drives if I remember the number of drives correctly). If they are able to slip 160GB drives into that, it would put it up to about 2.2TB... Sweet either way. :D
     
  15. mmcneil macrumors regular

    Joined:
    Sep 4, 2001
    Location:
    San Diego, CA
    #15
    RAID & the TiBook

    It could under two circumstances:

    1) You are doing most of your work using external RAID HD, including possibly booting from the external drive.

    2) Future - you could equip your TiBook with multiple iPod size drives:D Now that would be a cool upgrade to go with the fantasy of dual CPU TiBooks
     
  16. AlphaTech macrumors 601

    AlphaTech

    Joined:
    Oct 4, 2001
    Location:
    Natick, MA
    #16
    You can use Raid to kill bugs too... Works pretty well. :p

    You would need to either purchase a FireWire RAID solution ($$$) or get a few drives and set it up under OS X. Either way, it's gonna cost you lots of green.
     
  17. Catfish_Man macrumors 68030

    Catfish_Man

    Joined:
    Sep 13, 2001
    Location:
    Portland, OR
    #17
    Re: Clustering?

    The cluster I set up was a Powerbook G3 233MHz running OS 8.6, and a G4 450MHz (Sawtooth) running 10.1.2 (I think). Also, why wouldn't a cluster need raid?
     
  18. mmcneil macrumors regular

    Joined:
    Sep 4, 2001
    Location:
    San Diego, CA
    #18
    Apple Certification?

    Hey alphatech - what is the process for achieving certification? Is it all through apple? Can it be done on-line? How much $$?
     

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