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Thread: 8-bay Burly, 6x G2 X15s, UL3D, G4-800DP

  1. #1
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    I can confirm what MacMikester said here http://www.macgurus.com/ubb/Forum1/HTML/000206.html (I'm nonsensical my wife says).

    To see where the limits were, I built up the Burly first with 2x G2 18GB X15s, one on each channel, all Granite external LVD cabling and Burly internal LVD cabling and LVD terminators, then 4x X15s with two per channel, finally 6x X15s with three per channel. All SoftRAID 2.2.2 with ATTO UL3D firmware 1.64, OS9.2.1.

    These are new drives and will be faster when they wear in. I did not optimize the directory or the drives or change factory default Mode Page Parameters. Just ran the tests once for each config. ATTO test, 8MB, Sample Size 2, no System Disk Cache. MacBench 5, Disk and Pub Disk tests.

    UPDATE 12/01/01 - I forgot to mention yesterday that I left my internal 2x G2 X15s on one channel striped RAID attached to the UL3D and running. So that may have been hogging some bandwidth tho I ran the ATTO and MB5 tests from one of the ATA drives. I will rerun the Burly 6x striped RAID tests later with the internal RAID disconnected.

    2x G2 X15s, one per channel, 256SU:
    ----------------------------------
    ATTO test, PR-213.88, SR-111.53, PW-161.21, SW-118.11
    MB5, D-5297, PD-4467

    4x G2 X15s, two per channel, 256SU:
    ----------------------------------
    ATTO test, PR-204.02, SR-190.31, PW-201.65, SW-196.66
    MB5, D-6101, PD-4541

    6x G2 X15s, three per channel, 256SU:
    ------------------------------------
    ATTO test, PR-218.54, SR-194.94, PW-204.06, SW-197.93
    MB5, D-6337, PD-4676

    6x G2 X15s, three per channel, 128SU:
    ------------------------------------
    ATTO test, PR-218.17, SR-193.60, PW-198.72, SW-186.86
    MB5, D-6158, PD-4743

    Note, the smaller stripe size will increase PD in MB5. The larger stripe size will increase D. I have seen this numerous times before. k


    [This message has been edited by kaye (edited 01 December 2001).]

  2. #2
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    Further testing, first back to 6x G2 X15s, three per channel, 256SU. Disconnected internal striped RAID. Then optimized the directory and optimized the RAID with Speed Disk.

    6x G2 X15s, three per channel, 256SU:
    ------------------------------------
    ATTO test, PR-214.75, SR-196.78, PW-202.85, SW-197.73 (about the same as previous 256SU test)
    MB5, D-6463, PD-4728 (up 2% and 1% respectively)

    Yesterday I configured for 2x UL3D and three drives each on one channel of each UL3D. Rebuilt the striped RAID and optimized directory and drives.

    6x G2 X15s, 2x UL3Ds, three per one channel, 256SU:
    -----------------------------------------------------
    ATTO test, PR-232.22, SR-203.94, PW-206.01, SW-202.26

    This configuration adds about 7MB/s to SR and 4.5MB/s to SW. For the cost of another UL3D, not significant enough for me. k

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    Kaye,
    Wow - thanks for doing this research - its great that the theoretical and actual results line up. One question - I'm guessing that the difference between the 4 and 6-drive arrays might be more pronounced in a worst-case (ie. near the center of the platter) situation. Can you test that??

    Taffy.C

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    Mr. theoretical says:

    The differences will be the same if you are testing the inner tracks in all configs. Only the actual throughput numbers will be lower, but the differences will be about the same.

    [This message has been edited by MacMikester (edited 05 December 2001).]

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    Taffy.C,

    I agree with Mr. Theoretical. I will test the six drive array off of one UL3D by creating the smallest second partition I can. Is that what you are looking for, or did you want me to try that with both six and four drive arrays on one UL3D? Let me know.

    BTW, these six new G2 18GB X15s have firmware 0004 and all even have the same build number. The two G2 X15s I purchased earlier are firmware 0002 as I recall. Anyway, these 0004 drives have slightly higher SW. All the Mode Page Parameters are identical. So the difference appears to be firmware or I suppose it could be something mechanical. k

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    Hi Kaye,
    I was interested in a comparison of 4-drive vs. 6-drive performance on the inner platters with one UL3D. My thought was that in the best-case scenario both configs are running pretty close to the PCI slot max throughput, so you don't see much difference - i.e. they are limited by the PCi performance. But in a worst case situation where you are on the inner platters, the speed will be determined by array performance. And 6 drives must be faster than four? Although.... Seagate does spec the X15s at 51MB/s worst case, so 4 x 50 is still 200MB.

    The reason I am interested in this is that for high-def 10-bit video I need sustained throughput of 170MB/s and I need to understand how many X15s I need to support this in the worst case. Probably 4, but I'd love it if you could do the measurement.

    .... Taffy.C

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    One nice think Seagate has managed with the 2G X15 is that it does not really seem to degrade as any other drive will as it gets loaded (though I believe in keeping to 60% full or less). The need to stripe outer tracks might not be as necessary. Usually I'd create a 2nd striped volume for slower static files on the inner most tracks. Single drive, keeps right up in the 51MB/s SW (and almost the same for reads).

    Gregory

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    Taffy.C,

    I'll try it tomorrow morning, both 4x and 6x drives on two channels on one UL3D. k

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    Taffy.C,

    G4-800DP, tested the Burly with 6x G2 X15s on one UL3D, three per channel. And tested with 4x G2 X15s on one UL3D, two per channel. Rebuilt each striped RAID, optimized the directory and defragged then optimized the directory again.

    For the 6x, I created two partitions, the first 104409MB, the second 600MB (100MB per drive). This is really the inner tracks of each drive. I don't think anyone would do serious work with only a total of 600MB left. But the test:

    6x G2 X15s, three per channel, 256SU, Partition 2 (600MB):
    ---------------------------------------------------------
    ATTO test, PR-220.83, SR-181.90, PW-202.57, SW-195.12
    MB5, D-6281, PD-4578

    The above ATTO test (8MB, Sample Size 2, no System Disk Cache) was the best of 12 tests. The SR range 176.80-181.90 with most around 179, SW range 186.65-195.12 with almost all in the 193-194 range. This config would more than satisfy your need for a minimum of 170MB/s.

    For the 4x, I created two partitions, the first 69606.5MB, the second 400MB (100MB per drive).

    4x G2 X15s, two per channel, 256SU, Partition 2 (400MB):
    -------------------------------------------------------
    ATTO test, PR-214.28, SR-153.68, PW-183.58, SW-167.03
    MB5, D-5805, PD-4320

    Whoa, not so good. Once again, the above ATTO test (8MB, Sample Size 2, no System Disk Cache) was the best of 12 tests. The SR range 151.21-153.68 with most around 152-153, SW range 163.54-167.03 with most around 166. This config would not satisfy your need for a minimum of 170MB/s.

    Not satisfied with that, so I created a new 4x, two partitions, the first 67958.5MB, the second 2048MB (2GB), thinking that perhaps a more reasonable 2nd partition of 2GB would bring the performance back.

    4x G2 X15s, two per channel, 256SU, Partition 2 (2048MB):
    --------------------------------------------------------
    ATTO test, PR-217.03, SR-153.58, PW-183.84, SW-167.84
    MB5, D-5874, PD-4413

    Again the above ATTO test was the best of twelve. No point in the ranges. Still does not meet your needs. And contrary to what I thought before, the drop with 4x and dual channel is much more significant than the drop with 6x on the inner tracks. My guess is because the 6x dual channel on the outer tracks reaches a PCI slot ceiling with one UL3D before it reaches a striped drives ceiling whereas the tests on the inner tracks is reaching the striped drives ceiling, if that makes sense. So many numbers, hope I copied it all correctly. k

    [This message has been edited by kaye (edited 07 December 2001).]

  10. #10
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    Kaye,
    Thanks a bunch for all this work! What you discovered was exactly what I was concerned about - that the 4 drive array performance would suffer on the inner platters. I will have to upgrade myself to a 6 drive array - does the need for more money never cease!

    One further question - I don't understand the Seagate spec of 51MB/s min for the G2 X15. I thought that that would mean that the worst-case (drive limited) performance would give me 204MB/s min for a 4-drive array. Am I missing something?

    Thanks again ... Taffy.C

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    That spec INTERNAL FORMATTED TRANSFER RATE (MB/sec)_51.8 to 68.1 is an internal transfer rate somewhere between disk and onboard cache, not the external rate, which they only give as:
    EXTERNAL TRANSFER RATE (mbyte/sec) _______40 Sync
    Low Voltage Differential(LVD) _______80/320 Sync

    In addition to the drives, your rate is affected by your SCSI card, PCI bus speed, RAID overhead, stripe size, Mode Page Parameters, and the test utility (and probably others that I can't think of at this time of night). k

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    All these tests are very interesting, but I think I (and others?) would be interested in what you can do with the same hardware in
    Mac OS 10.1

    I would also like to see FINDER copies & duplications in Mac OS 9 & 10.
    I bet there would be better peformance with a 4 drive stripped array in 10.1 than with classic. Does the RAID software in 10.1 even support more than two drives on a single volume?

    There was a simple test done on networking -
    100baseT vs. 1000baseT vs. 1394 IEEE on Windows (2K I think) and Mac (system 10.1). 400Mbps Firewire is almost exactly as fast as 1000baseT. What is more - all these 'networking' technologies are faster on a MacOS 10 powered system (867MhzG4 vs. 2Ghz P4 - IIRC).

    Hopefully SoftRAID will be out for 10 in 6 months... maybe by next Christmass.

    ------------------
    To boldly go where no english professor has gone before! -)

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    At 170MB/s you will need about 10GB of space per minute of video. For one hour of video you will need 600GB.

    Maybe you really need the 4x36GB x15 setup anyway - since it can only handle 43min of video. Maybe Seagate needs to get those 72GB x15s to market?

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    d_x,

    Yup, I have to wait for SoftRAID to handle OSX. If I recall correctly, Taffy.C has 4x 36GB G2 X15s, and is considering adding two more.

    You lost me on the math. If "you will need about 10GB of space per minute of video. For one hour of video you will need 600GB. Maybe you really need the 4x36GB x15 setup anyway - since it can only handle 43min of video." How does 43 minutes of video with 4x 36GB compute, if you need 430GB for 43 minutes? I'm not disputing your 10GB per minute, just can't make the math work. k

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    Hi Kaye, d_x,
    Yep - some 73G X15s would be nice. I am probably going to end up with at least 8 x 36G drives I suspect - just to get some reasonable storage time for High -def.

    Here's another thought that I am wondering about - when you output an edited video to tape from the Non-Linear-Editor, the NLE is basically throwing together lots of separate clips (files) from the array into a continuous stream of video.

    The array performance tests which we have been talking about here so far are for continuous read/write of a single file. How do we measure the effective sustained read speed when the array is accessing multiple sequential files all over the disk. Any thoughts on that?

    .... Taffy.C

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    Taffy.C,

    You have stumped me there. But the seek and average access time of the drives is very small. One other point, the ATTO test is not one file size, actually a whole variety of file sizes, tho undoubtedly contiguous, from 32KB up to 8MB, and more than the selectable sizes shown in Max Transfer Size (according to the ATTO docs). k

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    Hey k, QuickBench Random Read/Random Write tests should approximate the result that Taffy is looking for. The choices of smaller file sizes may not be quite the same as as streaming huge video files together but should give him some idea of the worst-case scenario.

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    Great idea MM. Only drawback is that it will only test RR and RW up to 1MB file sizes. The 10MB size won't do it, only sustained read/write. Taffy.C, want to try it and post results? k

    [This message has been edited by kaye (edited 13 December 2001).]

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    How does 43 minutes of video with 4x 36GB compute, if you need 430GB for 43 minutes?
    You are right... I must have done crazy MATH in my sleep or something.


    4x36GB is only about 15 minutes of video at his data throughput requirements. I think I mis read 4x36 AS 436GB - thus the 43 minutes of video. Of course if someone could invent a RAID cluster that could do this - they would get RICH!

    So what kind of video requires 170MB/s data? I gotta know!

    I gues it would be higher resolution than MPEG2 with NO Compression at all? Would this be for movies or iMax movies?

    Many - you are going to need one hell of a backup system. I think the biggest tapes only do about 80GB compressed (2:1) - but you can get a bank of tape drives - those DLT 4 drives are EXPENSIVE - about $3,500 for a single drive + tapes + cables + card + software.

    I think an 8 drive RAID-0 setup is the biggest (drive wise) that runs with SoftRAID.... I've never heard of any body trying anything bigger.

    ------------------
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    I wish I had some of these benchmarks http://www.athlonmb.com/article-disp...ID=51&PageID=4 k

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