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Date:      Thu, 18 Aug 2016 08:56:55 -0400
From:      Allan Jude <allanjude@freebsd.org>
To:        =?UTF-8?Q?Dag-Erling_Sm=c3=b8rgrav?= <des@des.no>, Nathan Whitehorn <nwhitehorn@freebsd.org>
Cc:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   Re: svn commit: r304142 - head/usr.sbin/bsdinstall/partedit
Message-ID:  <2f9fb04c-7ec4-be40-8fcb-0cf74bb56859@freebsd.org>
In-Reply-To: <86fuq24d8s.fsf@desk.des.no>
References:  <201608150930.u7F9UL1V069576@repo.freebsd.org> <e3454e8e-5d98-5bec-21de-8ea0db2b9b08@freebsd.org> <861t1n6749.fsf@desk.des.no> <581c856c-826b-529e-c9c6-a397fb679708@freebsd.org> <86wpjf4eun.fsf@desk.des.no> <8cb3fa1a-50cb-e238-d006-b98a628d446d@freebsd.org> <86k2ff4cxs.fsf@desk.des.no> <b96c3f91-faaa-2552-b4da-2d0d382461af@freebsd.org> <86fuq24d8s.fsf@desk.des.no>

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On 08/18/16 05:50 AM, Dag-Erling Smørgrav wrote:
> Nathan Whitehorn <nwhitehorn@freebsd.org> writes:
>> OK. In which configurations? My Dell servers, for instance, don't do
>> this. How are they set up? What drivers are being used? Is this
>> something that affects passthrough disks, RAIDs, disk images?
> 
> Most LSI MegaRAID controllers don't have real passthrough, only JBOD.
> You can query the drive with "camcontrol identify passX", but the
> controller does not report a stripe size for the volume (mfidY).
> 
>> The point is that *if the reported stripe size is wrong*, more things
>> than partition alignment in the installer will suffer for it.
> 
> It's not wrong, it's non-existent, and I'm getting really tired of
> repeating myself.
> 
>> Fixing the installer with a bandaid in the run-up to a release is
>> fine, but *we need to fix the underlying problem*.
> 
> We can't, because hardware sucks, and I'm getting really tired of
> repeating myself.
> 
> DES
> 

Which makes more sense:

A) If stripesize == 0, use some sane value like 4096

B) Some other combination that uses the reported stripe size, unless it
is 0, in which case it uses 4096 (or some other value controlled by a
different new sysctl)

C) create kern.geom.min_stripe_size with a default of 512, but users can
set 4096 if they use only 4k devices. (doesn't really solve the problem
for the installer)



-- 
Allan Jude



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