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List:       dm-devel
Subject:    [dm-devel] Re: [PATCH 7/9] scsi_dh: Add support for SDEV_PASSIVE
From:       Chandra Seetharaman <sekharan () us ! ibm ! com>
Date:       2008-02-28 1:03:30
Message-ID: 1204160610.4963.49.camel () linuxchandra
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On Mon, 2008-02-11 at 12:18 -0700, Matthew Wilcox wrote:
> On Mon, Feb 11, 2008 at 10:27:46AM -0800, Chandra Seetharaman wrote:
> > On Sat, 2008-02-09 at 05:45 -0700, Matthew Wilcox wrote:
> > > On Mon, Feb 04, 2008 at 01:19:30PM -0800, Chandra Seetharaman wrote:
> > > > The device does send these error messages currently, but it takes some
> > > > time to get the check condition back, which adds up the time to boot
> > > > especially when the # of LUNS is huge.
> > > > 
> > > > For example, in my test configuration, I had 40 luns, and the time
> > > > difference (with this patch and without it) to boot is 171 seconds and
> > > > 1426 seconds.
> > > 
> > > Was that with sync or async SCSI bus scanning?
> > 
> > I didn't change anything, IOW, i did default scanning, which I would
> > guess sync ?!
> 
> That would depend on your CONFIG_SCSI_SCAN_ASYNC setting.
> 
> Try booting with 'scsi_mod.scan=async' and without this patch, and see
> how long it takes.
Hi Matthew,

scanning in async mode did not help in reducing the boot time.

I even changed the configuration, such that 20 active luns and 20
passive luns are in each path, it still didn't change the time it took
to reboot.

regards,

chandra
> 
-- 

----------------------------------------------------------------------
    Chandra Seetharaman               | Be careful what you choose....
              - sekharan@us.ibm.com   |      .......you may get it.
----------------------------------------------------------------------


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