lkml.org 
[lkml]   [2009]   [Jul]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: deterministic scsi order with async scan
    On Thu, 16 Jul 2009, Matthew Wilcox wrote:

    > On Wed, Jul 15, 2009 at 06:09:22PM -0700, david@lang.hm wrote:
    >> is there any way to get deterministic device ordering with scsi async
    >> scanning?
    >>
    >> currently (2.6.30) it seems that the various scsi busses are loaded in
    >> the order that they are detected, which can vary from boot to boot
    >> depending on how long it takes for the card to initialize.
    >
    > I think you're confused. The async scsi scanning was designed to _not_
    > move devices around randomly. There are other asynchronous schemes in
    > the kernel, some of which were not designed with the same care.
    >
    > The SCSI async scan can't do much about it if the busses are detected
    > in a different order.
    >
    >> would it be possible to detect the cards/drives, but not register them
    >> until all the detection is complete so that they can be registered in a
    >> deterministic order?
    >
    > That's exactly how the scsi async scanning works.

    hmm, in that case how can I troubleshoot why this system is detecting the
    two different PCI-E cards in different orders on different boots.

    David Lang

    >> having two drives on two different controllers swap positions from boot
    >> to boot makes it very painful. yes I can make an initrd that fixes this
    >> up in user space by examining each drive and creating links to re-order
    >> them, but this is a lot of work to fix randomization that can be
    >> prevented in the first place.
    >>
    >> David Lang
    >> --
    >> To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
    >> the body of a message to majordomo@vger.kernel.org
    >> More majordomo info at http://vger.kernel.org/majordomo-info.html
    >
    >


    \
     
     \ /
      Last update: 2009-07-16 19:25    [W:4.001 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site