> On Aug 18, 2016, at 11:21 PM, Nathan Whitehorn <nwhiteh...@freebsd.org> wrote: > > > > On 08/18/16 21:15, Warner Losh wrote: >> On Thu, Aug 18, 2016 at 6:56 AM, Allan Jude <allanj...@freebsd.org> wrote: >>> On 08/18/16 05:50 AM, Dag-Erling Smørgrav wrote: >>>> Nathan Whitehorn <nwhiteh...@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 >> >> > > That sounds good to me and I think can clean up a lot of code and potential > foot-shooting. Who is planning to make the patch? I'm happy to do anything > that would be helpful.
The patch is super-easy, but I need to get the concept validated and make sure that it does not have unintended side effects. Warner
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