svn commit: r304142 - head/usr.sbin/bsdinstall/partedit

[Warner Losh]

On Thu, Aug 18, 2016 at 6:56 AM, Allan Jude <allanjude at freebsd.org> wrote:
> On 08/18/16 05:50 AM, Dag-Erling Smørgrav wrote:
>> Nathan Whitehorn <nwhitehorn at 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

I don't like this.

> 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)

Don't like this so much.

> 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)

Default it to 4k, and allow users to set it to 512. If the drive
reports < this value
report this value instead. You'll need to make this a tunable. Then the upper
layers wouldn't care. There's a small chance that some SD cards might be
reporting values that are too large. But I think it is confined to SD cards and
if I see too many more I'll do something specific in the SD driver.

Warner