Re: SCSI flash system disk on VMS ?

From: Hoff Hoffman (hoff_at_hp.nospam)
Date: 07/20/04

  • Next message: Richard Tomkins: "Re: SCSI flash system disk on VMS ?" 
    Date: Mon, 19 Jul 2004 23:20:02 GMT

    In article <f486c91c.0407181706.52007836@posting.google.com>, alegend@mail.com (Al) writes:

      These look to be specialized storage devices; I'll assume you
      have environmental and/or application requirements to match.

    :Has anyone ever tried attaching a SCSI flash disk drive
    :(http://www.m-systems.com/content/Products/product.asp?pid=13) to a
    :VAX/MicroVAX as a system disk ?

      OpenVMS will bootstrap off various electronic storage devices,
      and has been seen to operate off a wide variety of SCSI storage
      including various solid-state disks, and off some flash devices.

    :These drives are fast and reliable but I don't know whether their
    :guaranteed 5M erase/write cycles will run out too quickly due to some
    :background process disk writes.

      OpenVMS is multiuser and multiprocessing, meaning that there are
      almost always servers and such running all the time.

      The widget might be a good mechanism as a data or application
      disk, of course, then you would have better control over the use.

      One thing that is not entirely clear (to me) is if that cited
      5,000,000 writes figure is for the whole disk, or for a particular
      storage location such as the data storage behind a sector or a
      block.

      Some of the local folks have been discussing and have been
      expermenting with USB flash devices with OpenVMS -- yes, we can
      bootstrap certain OpenVMS configurations off USB flash disks --
      and have been considering what the lifetime might prove to be.
      AFAIK, we have not tried any "accellerated lifetime experiments",
      nor are there any plans for such.

    :Is there something in OpenVMS that will unnecessarily eat away the
    :flash disk's maximum number of writes ? some logging I will have to
    :disable ?

      That depends on your definition of "unnecessarily". OpenVMS
      can bootstrap from a write-locked disk, after all.

      It might be feasible to configure and load OpenVMS, then to
      write-lock it, then operate with the writeable storage on a
      second device -- sacrificial or otherwise, or potentially
      some other DRAM or other solid-state storage, or a ruggedized
      mechanical disk, etc.

      If the device supports the revectoring of bad blocks (and the
      write limits are per-block), you might get a somewhat longer
      lifetime out of the device. If the lifetime is disk-wide,
      well, ugh... That's tougher...

      You could certainly boot and run and monitor the I/O counts,
      of course, and see how quickly the writes accumulate in your
      particular environment -- using standard disks, of course.

     ---------------------------- #include <rtfaq.h> -----------------------------
        For additional, please see the OpenVMS FAQ -- www.hp.com/go/openvms/faq
     --------------------------- pure personal opinion ---------------------------
            Hoff (Stephen) Hoffman OpenVMS Engineering hoff[at]hp.com

  • Next message: Richard Tomkins: "Re: SCSI flash system disk on VMS ?"

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