From: Harvey, Bruce T. (BTHarvey@LMUS.LEGGMASON.COM)
Date: Wed Nov 12 2003 - 19:29:35 EST
Simon,
This adapter doesn't support the command you outline. We have "rumor" and
"hearsay" that a device not set to F/W in the loop can cause the adapter to
take longer processing for all disks. We shall see.
Many thanks!
-----Original Message-----
From: Green, Simon [mailto:Simon.Green@EU.ALTRIA.COM]
Sent: Wednesday, November 12, 2003 6:26 AM
To: aix-l@Princeton.EDU
Subject: Re: SSA, Fast Cache En-/Dis-abled on the same adapter/loop
You can check the cache status with the command "ssa_fw_status -a ssa0 -c".
I can't see anything in the User Guide which indicates it can't be activated
for individual disks. I've always had it active for all disks, except when
a new disk has just been installed; I don't recall any problems under those
circumstances.
Simon Green
Altria ITSC Europe Ltd
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> -----Original Message-----
> From: Harvey, Bruce T. [mailto:BTHarvey@LMUS.LEGGMASON.COM]
> Sent: 11 November 2003 19:08
> To: aix-l@Princeton.EDU
> Subject: SSA, Fast Cache En-/Dis-abled on the same adapter/loop
>
>
> Folks,
>
> We have four physical 9.1Gb SSA drives on one (IBM SSA 160 SerialRAID)
> Adapter with Fast-Write enabled (three are arranged into a
> raid-5 array and
> one is a system disk) and a fifth physical drive on the same
> controller and
> system has Fast-Write DISabled. Will this slow down the
> entire set of disk
> to where it's as if the fast-write is disabled for all of them?
>
> That appears to be what we are seeing, but no one currently
> knows if the
> time prior to when we started seeing slowness all the disks
> had it enabled
> or the config's exactly like we see it now --- "our bad."
>
> Do I understand the SSA looping and adapter characteristics
> properly in that
> if it's not on for everyone, it's not on, or at least there's severe
> degradation from what it could be?
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