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Topic: Raid for GIGA (that good?)

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  1. #1

    Question Raid for GIGA (that good?)

    Is a Raid system of any advantage to a giga system?

    Raid 0 that is - the one where the data is split across 2 drives

    I though that this system was particularly good for large amounts of sequential data - like video and may be audio (if you're doing long takes at high resolution).

    Can it increase poly counts?

    I figure that the disk heads would need to be moving so much more in a raid 0 system.

  2. #2

    Re: Raid for GIGA (that good?)

    I haven't done it myself, but yes, it works in theory - and in practice according to Tascam and many on this forum. Two Raptors really do the trick. Two 15,000 RPM SCSIs would really fly - if you can tolerate the noise.

    -JF

  3. #3

    Re: Raid for GIGA (that good?)

    Quote Originally Posted by JonFairhurst
    I haven't done it myself, but yes, it works in theory - and in practice according to Tascam and many on this forum. Two Raptors really do the trick. Two 15,000 RPM SCSIs would really fly - if you can tolerate the noise.

    -JF
    i would not go for scsi, at least not on pci.
    s-ata raid system with wd´s 10.000 rpm drives can give you up to 125mb / sec.
    you would not get this on a pci bus because the theoretical pci bus troughput is something like 130mb / sec. but normaly its more like 70-110mb depending on the motherboard. besides this its really expensive.
    Digital AudionetworX

    ______________________________
    http://www.digital-audionetworx.de
    mac - pc - gigastudio
    berlin - germany

  4. #4

    Re: Raid for GIGA (that good?)

    True. Raptors are much more economical and plug right into the MB.

    The main advantage for the 15k rpm disks is that the seek time is lower. That's the main limiting factor for Giga - especially if you're doing fast percussion. It doesn't matter how much bandwidth you have if the physical disks can't get to the data in time.

    Let's say your PCI bus limits you to 100 mBps. Each 24-bit 44.1 kHz voice costs 132.3 kBps. That leaves room for 755 voices! Then again, PCI Express is coming...

    Nonetheless, I'd go for Raptors, unless money and noise were non-issues. Then I'd buy one set of each, pay my assistant to test to find the fastest, build a room full of the fastest machines and light my cigar with a $100 bill.

    -JF

  5. #5

    Re: Raid for GIGA (that good?)

    Quote Originally Posted by JonFairhurst
    Nonetheless, I'd go for Raptors, unless money and noise were non-issues. Then I'd buy one set of each, pay my assistant to test to find the fastest, build a room full of the fastest machines and light my cigar with a $100 bill.

    -JF
    That's vey kind of you

    Not the seagate's then? I heard that these were good - quiter as well

    Or do I really need 10,000rpm drives?

    I still think that a raid system in a giga system will cause the HD heads to fly - but if they do work I won't argue.

  6. #6

    Re: Raid for GIGA (that good?)

    Yes been running raid 0 with my 2 7200 drives... These work great on my dedicated giga machine as well as in my dedicated audio machine... Both have raid 0, been running that for 3 or more years.. Never had a drive go yet!!!! I back up... Previous to running raid 0 I had always had touble getting any sort of performance from either machine... My raid controller is on the PCI bus!!! I can't wait to go raid ) off with sata drives off the PCI bus... Might open up a bit more throughput, hopefully!!
    But I'm holding off till GS3 can handle more then 2 gigs of ram properly before I buy another system!
    Later
    Bri

  7. #7

    Re: Raid for GIGA (that good?)

    Quote Originally Posted by seclusion
    Yes been running raid 0 with my 2 7200 drives...
    And what kind of polycounts are you getting with that?

    Perhaps a brief round up of the rest of your hardware (giga machine only of course) ? If you don't mind

    Sorry - you've got GS2.5

    Perhaps I'll start another post on that subject.

  8. #8

    Re: Raid for GIGA (that good?)

    Quote Originally Posted by JonFairhurst
    Let's say your PCI bus limits you to 100 mBps. Each 24-bit 44.1 kHz voice costs 132.3 kBps. That leaves room for 755 voices! Then again, PCI Express is coming...
    Nonetheless, I'd go for Raptors, unless money and noise were non-issues. Then I'd buy one set of each, pay my assistant to test to find the fastest, build a room full of the fastest machines and light my cigar with a $100 bill.
    -JF
    the acces time is not that important since all samples are preloaded anyway.
    more important is the overall troughput. and in this case S-ATA is better than SCSI-PCI.

    "Each 24-bit 44.1 kHz voice costs 132.3 kBps"

    132,3 kb / sec.??? where did you read that?

    pure audio on 16 bit and 44.1 is something like 154 kbyte/sec. (i forgot the exact last digit) or 176kb (something like that) on cd because off the error correction.

    or something like that. to be on the save side i calculate with 176kb.
    (streaming audiodate from disk needs actually more troughput)


    so 16bit * 1.5 = 24bit ok? which means 1 stereo 24bit track is something like 264kb / sec.

    lets say you play back 400 voices you need 105.60 MB / sec.

    in this case PCI SCIS would definitly fail.

    and thats not a rare case for sure.
    Digital AudionetworX

    ______________________________
    http://www.digital-audionetworx.de
    mac - pc - gigastudio
    berlin - germany

  9. #9

    Re: Raid for GIGA (that good?)

    Ya sorry, I'm just in the middle of getting GS3 up and running as smooth as 2.54. I'm still on an old P3 1 giger with 512 ram (maxed) and 2 ata133 7200 drives running raid 0.... Again, back when I was praising the raid 0 setup, everyone talked about performance #'s.. I did the 160 all day long... Again I have had these drives running for 3 + years on 2 identical system... Think of raid 0 taking a load off of your drives... Each access comes from a different drive... So I'm not hammering 1 drive all to sh@t while the other sits there unless I ran out of poly... Choice is yours but for $100 more, you won't be changing you're drives as often if you work em hard... Someone I know has 4 - 120 gig sata drives running off of the main board Raid 0.... But he won't let me load giga on it to see if I can kill it!! He just uses it for games!!! Damn what a shame!
    Later
    Bri

  10. #10

    Re: Raid for GIGA (that good?)

    Quote Originally Posted by Digital AudionetworX
    "Each 24-bit 44.1 kHz voice costs 132.3 kBps"

    132,3 kb / sec.??? where did you read that?
    I didn't read it. I calculated it.

    44,100 samples/second * 24 bits/sample / 8 bits/byte = 132,300 bytes/second. All error correction and overhead is built-into the hard drive hardware, so there are no additional bits required on the bus.

    Come to think about it, Giga has a new disk compression scheme. If, on average it compresses 1.33 to 1 (if!), we're looking at around 1,000 voices over a 100 mBps bus at the limit. Go down to 16 bits and it's 1,500.

    Of course, there is overhead in general on the bus, so you won't reach that limit, but with DMA large chunks of data can move at full speed.

    Regarding throughput and seek time, both are important. Keep in mind that the samples that you want aren't sequentially stored. If the average seek time is 5 ms, the head can only read 200 voices within one second. If the system reads and caches more than a second worth of audio when it gets the chance, you can play more than 200 voices with such a system, but there are limits.

    We really want it all: multiple fast disks, fast seek times, fast busses, lots of RAM/cache and a CPU that is capable of holding it all together.

    Then again, I'm just running a 7,200 RPM Seagate on an AMD 2500+. Christmas time is upgrade time.

    -JF

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