Q: rx6600 slot assignment - Hewlett Packard

This is a discussion on Q: rx6600 slot assignment - Hewlett Packard ; Hi, for an rx6600 Itanium2 server which features 66, 133,1and 266 Mhz PCI-X slots the default configuration ships with the SAS RAID controller in a 66 MHz slot, as well as the Gb LAN card. Assuming 64bit cards, some simple ...

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Thread: Q: rx6600 slot assignment

  1. Q: rx6600 slot assignment

    Hi,

    for an rx6600 Itanium2 server which features 66, 133,1and 266 Mhz PCI-X slots
    the default configuration ships with the SAS RAID controller in a 66 MHz slot,
    as well as the Gb LAN card.

    Assuming 64bit cards, some simple math suggests that the theoretical peak
    burst transfer rate for 66 MHz is 528 MB/s. In practice it's maybe 1/3rd or
    1/4th of it. On an AMD Opteron server with two SAS disks a RAID1 can read at
    120 MB/s roughly, and I'd expect more disks to provide even faster rates
    (unless the controller is slow).

    As the 4Gb FC-Adapter is located in a 266 MHz slot, I wonder whether the RAID
    controller shouln't be put into a faster slot, while the FC-HBA might work
    optimal even in a 133 MHz slot.

    Any insights?

    Regards,
    Ulrich

  2. Re: Q: rx6600 slot assignment

    Ulrich Windl wrote:
    > for an rx6600 Itanium2 server which features 66, 133,1and 266 Mhz
    > PCI-X slots the default configuration ships with the SAS RAID
    > controller in a 66 MHz slot, as well as the Gb LAN card.


    Thost would be slots 1 and 2 yes? Just to be paranoid, you do know
    that the initial version of the QuickSpecs for the rx6600 (and rx3600)
    were incorrect in their identification of the I/O slot specs yes? It
    should be:

    Slot Type
    3 Independent 266 MHz
    4 Independent 266 MHz
    5 Independent 133 MHz
    6 Independent 133 MHz
    7-8 Shared 66 MHz
    9-10 Shared 66 MHz

    > Assuming 64bit cards, some simple math suggests that the theoretical
    > peak burst transfer rate for 66 MHz is 528 MB/s. In practice it's
    > maybe 1/3rd or 1/4th of it.


    If it is PCI-X, with split-transaction support, I'd think that 1/3 or
    1/4 is probably pessimistic. I'd probably guess 2/3d's or more -
    maybe even 4/5th's although I cannot say I have hard data to back that
    up, just recollections of past discussions elsewhere.

    > On an AMD Opteron server with two SAS disks a RAID1 can read at 120
    > MB/s roughly, and I'd expect more disks to provide even faster rates
    > (unless the controller is slow).


    While I have access to an rx6600 I am using for 10G Ethernet testing,
    it is not setup to do iozone testing - not enough internal mechs. I'd
    suggest just going ahead and running some tests to see what happens.
    FWIW, netperf4 has, of all things, disc I/O tests in it now too, which
    means you could do some simultaneous disc and networking tests. Of
    course FTP could cause that to happen too

    BTW, I just recalled that based on the flawed QuickSpecs I'd put an
    AD144A 10G NIC in a 66 MHz slot, and with it I was able to get 2.6
    Gbit/s on netperf tests (G == 10^9). That is ~310 MB/s (M == 1024^2)
    which is just shy of 60% of the theoretical peak burst you calculated
    above. I guess your stuff above is powers-of-ten, in which case that
    is 325 MB/s (M == 1000^2) which is just shy of 62% - still not quite
    the 2/3 I was saying above but rather better than 1/3rd .
    Generally, networking has a higher ratio of control structure access
    to data DMA, and the DMA's tend to be smaller than mass storage.

    > As the 4Gb FC-Adapter is located in a 266 MHz slot, I wonder whether
    > the RAID controller shouln't be put into a faster slot, while the
    > FC-HBA might work optimal even in a 133 MHz slot.


    > Any insights?


    The SAS RAID and the Gb are "core" I/O.
    Slots 1 and 2 are the "core" I/O slots.
    ergo
    The SAS RAID and Gb go into slots 1 and 2.

    I doubt it was any more than that. Well, that and cable lengths and
    available paths from the SAS card to the internal disc slots. Now,
    whether or not the os/firmware/efi particularly care I doubt it...

    What is the specific product/part number of the 4Gb FC HBA? It is
    possible that it is a PCI-2.0 266MHz card and so was stuck in slot 3
    or slot 4 on that basis alone.

    rick jones
    --
    portable adj, code that compiles under more than one compiler
    these opinions are mine, all mine; HP might not want them anyway...
    feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH...

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