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Thread: AH residence

  1. #16
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    HP,

    http://h18006.www1.hp.com/products/s...ise/index.html

    The controller is called HSV110 and they are sandwiched between the loop switches in the pic at the beginning of the thread. Each disk shelf - one is at the top of the pic - has two power supplies - white and black cables - connected to separate power controllers on separate power circuits. The shelf is on two fiber loops connected to separate loop switches. There is a separate controller on each loop. The four switches are for the left and right sides of the cab, bottom and top.

    The controllers are connected to separate SAN switches and each host computer has a separate fibre-channel card on a separate I/O bus connected to each SAN switch.

    The object is to survive the failure of any single component including a disk shelf which comprises up to 14 x 306 GB disks. A cab can have 12 shelves - the one pictured has 6 and has lower-capacity disks as the cost/storage density trade off very much favors that.

    I'm using RAID 0, 1 and 0+1 - 0+1 in DEC parlance being stripes + controller based mirroring. The critical data use VMS host-based shadowing with 3-member shadow sets, one member at a DT site at what was formerly the USAF Space Command

    A lot less complicated than passive crossover networks which completely confound me.

    John
    Last edited by John Nebel; 03-19-2004 at 01:33 PM.

  2. #17
    Super Moderator Hofmannhp's Avatar
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    !!!!!

    Originally posted by John Nebel
    HP,
    Each disk shelf - one is at the top of the pic - has two power supplies - white and black cables - connected to separate power controllers on separate power circuits. The shelf is on two fiber loops connected to separate loop switches. There is a separate controller on each loop. The four switches are for the left and right sides of the cab, bottom and top.

    The controllers are connected to separate SAN switches and each host computer has a separate fibre-channel card on a separate I/O bus connected to each SAN switch.

    John
    thanks John,

    more security can not be done......an interesting system (virtual Raid). Dont stopp going this way for a stable AH


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  3. #18
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    HP,

    Nice 4435 avatar!

    It was almost scary when I realized that the controllers were working around the shelf failure to reestablish redundancy.

    John

  4. #19
    jtgyn
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    The right tool

    G'Day John,
    I am impressed, you have the right tools for the job.
    An EVA and VMS... is it a cluster?

    Regards Scott

  5. #20
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    Scott,

    Yes, a VMS cluster for the critical applications and Tru64 for all else. The cluster has a member in a remote location for DT and the gov't agency owning that site uses us reciprocally.

    The VMS and Tru64 hosts both share the HSGs and EVAs and use an ESL for backup.

    John
    Last edited by John Nebel; 03-19-2004 at 05:47 PM.

  6. #21
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    It is likely robust enough

    So it looks like the AH disk residence is better than I'd thought. I'd bought a spare set of contollers - and everything else - but the manual doesn't address the issue of controller replacement.

    A fellow from DECUS, Germany provided the helpful bit below and someone else slipped a pdf of the HP internal document on the subject over the transom.

    Interesting that a controller can be swapped without interupting I/O.

    Where is that knocking on wood smilie?

    "John,
    it is just a matter of swapping the controller! I have worked with EVA since firmware version 1 and we had controllers changed several times. You can even replace both controllers at the same time, because the metadata is on the disks (no, I haven't seen that myself, yet

    Best regards,
    Uwe"

  7. #22
    Dis Member mikebake's Avatar
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    John, thank you very much for your kind donation of gear and expertise.

    MBB

  8. #23
    Super Moderator Hofmannhp's Avatar
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    Re: AH residence

    Originally posted by John Nebel
    ....................of the HP internal ...............
    Hi All,

    I have to tell you, that it's not me......and I got no harddrive in me...


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  9. #24
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    It looks like the EVA finally works right - there have been no problems for a couple of months now. "Looks like" is used as a qualification so as to not tempt the gods into striking it with lightning. One can't be too careful about those things.

    It took about a year from when the device was first purchased to getting it really working in production. Recently it has cheerfully withstood a power failure while it was releveling data and two separate disk failures. Releveling is the black magic which occurs whenever disks are added or removed - all the data in a disk group are moved around so every physical disk has the same amount. This is concurrent with normal operation and there are doubly redundant batteries to protect cache memory against power failures.

    I confess I don't have a clue what MBTF means. SCSI disks are meant to have a 1,000,000+ MBTF and I've seen several disk failures in the last month.

    I'm always surprised how difficult it is to put a complex piece of equipment into a production operation, usually a lot more work than one imagines.

    ... and until recently I'd not realized how complex a speaker system is - it's just a box, right?

  10. #25
    Senior Member Don C's Avatar
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    It is MTBF. Mean Time Between Failures, and as applied to disk drives, it is a useless figure. I did some reading up on this a while back. The time is calculated by estimating what would happen if you ran the disk for the suggested life time, usually three to five years. They don't exactly advertise how long they actually suggest the disk be used though. Anyway, they then would(estimate) replacing it with a new one. And continue. At some theoretical point in the future, half of the drives used in the test will have failed at some point in their useful life. That's the MTBF. Well, that's my understanding of how they get those absurd numbers, I'm not actually in that business or anything. Since the drive manufacturers cannot test the actual MTBF, as it would take years, they use this method that they made up. They might as well just make up the numbers. A resulting number that far exceeds the useful life of the disk sounds good in the ads. I guess it's legal.

  11. #26
    Administrator Robh3606's Avatar
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    There are many ways to accelerate life tests to determine MTBF. The most common are elevated temperature, vibration levels, humidity. Basically an enviorment that is intentionally hostile and beats the daylights out of the device. The numbers they do publish, at least for Established Reliability Parts, ERMIL Mil parts, are real with years of testing to back them up.

    Rob

  12. #27
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    Thanks Don and Rob, and it looks like MBTF may not mean a lot for a disk drive.

    I did read a Seagate paper on disk reliability a while back and it made things sound like the disks would run forever.

    They are not cheap disks. The 10K disks were this price until the 15K versions came out...

    $2,367.39 Hewlett Packard 293568-B22 72GB 15K RPM 2GB FC HD UPG Fibre Channel 15K RPM

    I don't pay that much, but it is indicitive of the fact the disks are made to high standards and they are the ones the military buys.

    If PC disks are on the same price/reliability curve, save your data!

    IBM appears to have quit the disk manufacturing business do to reliability problems verging on scandal.

    John

    PS.

    It may be that the operating enviornment beats the disks up with a high I/O load well beyond that which the MBTF tests subject them to and the disks are more sensitive to I/O load than to temperature or other environmental factors.
    Last edited by John Nebel; 07-29-2004 at 02:31 PM.

  13. #28
    Senior Member Ian Mackenzie's Avatar
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    John,

    I well recall the cooks tour I did of the AH back office in Boulder.

    Out of sight but certainly not out of mind.

    Say hi to Ann for me.


    Ian

  14. #29
    Senior Member Steve Schell's Avatar
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    Many thanks to John Nebel

    John, I'd like to thank you from the bottom of my heart for hosting the site and doing such a marvelous job of it. As far as I'm concerned, the Lansing Heritage site now has four co-founders!

  15. #30
    jandregg
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    John, if you meant MTBF it stands for mean time between failures.

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