Re: Page datasets on SAN

From: Sandor W. Sklar (ssklar_at_STANFORD.EDU)
Date: 06/24/05

  • Next message: Vincent D'Antonio: "Re: Page datasets on SAN" 
    Date:         Fri, 24 Jun 2005 09:42:03 -0700
To: aix-l@Princeton.EDU

    We've got sort of the same problem on this issue. I've never seen an
    IBM document talking about this issue, but we use EMC PowerPath (with
    our Clariion-based SAN), and in the PowerPath 4.4 for AIX Release
    Notes document, it states this (on page 24):

         In rare cases, if the AIX swap device is stored on a CLARiiON
         LUN, your system may hang if all paths to the active SP are lost
         and the AIX code, required for PowerPath to complete a trespass
         operation, is swapped out of memory. If this problem occurs, you
         must manually trespass the LUN to the available SP and reboot
         the host.

    Unfortunately, aside from two internal drives (mirrored rootvg), the
    only storage on the system is Clariion, so we've had to with paging
    spaces on the SAN.

    We have had occasions where some of our AIX systems have hung
    (requiring hard reboot) due to a trespass issue on the SAN, but I've
    never been able to track down the definitive cause.

         -s-

    On Jun 24, 2005, at 7:17 AM, Holger.VanKoll@SWISSCOM.COM wrote:

    > you are talking about paging-spaces, dont you?
    >
    > I´ve never seen a doc from ibm that states ps on san is not
    > recommended and would be surprised if you could provide a link to it.
    >
    > if "ibm says" means "somebody thats working at ibm told me..." then
    > you can safely ignore it. you can find others at ibm that tell the
    > same, and others at ibm that tell something different.
    >
    > there are ps-recommendations; in short
    > dont place a ps on a disk where a ps already exists
    > dont place a ps on a disk where a mirror of a ps already exists
    >
    > and, by far not so important
    > keep all ps at the same size
    >
    > the only argument against ps on san that I see is cost
    > if your san is less reliable than internal disks, also reliability
    > is of concern - if a ps is not accessible anymore, the system will
    > crash
    >
    >
    >
    > From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On
    > Behalf Of Morris, Carey B
    > Sent: Friday, June 24, 2005 3:16 PM
    > To: aix-l@Princeton.EDU
    > Subject: Page datasets on SAN
    >
    > Is anyone aware of any good white papers or redbooks regarding
    > placing AIX page datasets on SAN storage? IBM says it is supported
    > but not recommended. What is their reasoning? Performance?
    > Reliability?
    >
    > Thanks,
    > Carey Morris

  • Next message: Vincent D'Antonio: "Re: Page datasets on SAN"

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