tip below… On Nov 13, 2011, at 3:24 AM, Pasi Kärkkäinen wrote:
> On Sat, Nov 12, 2011 at 10:08:04AM -0800, Richard Elling wrote: >> >> On Nov 12, 2011, at 8:31 AM, Pasi Kärkkäinen wrote: >> >>> On Sat, Nov 12, 2011 at 08:15:31AM -0500, David Magda wrote: >>>> On Nov 12, 2011, at 00:55, Richard Elling wrote: >>>> >>>>> Better than ? >>>>> If the disks advertise 512 bytes, the only way around it is with a >>>>> whitelist. I would >>>>> be rather surprised if Oracle sells 4KB sector disks for Solaris systems? >>>> >>>> Solaris 10. OpenSolaris. >>>> >>>> But would it be surprising to use SANs with Solaris? Or perhaps run >>>> Solaris under some kind of virtualized environment where the virtual disk >>>> has a particular block size? Or maybe SSDs, which tend to >>>> read/write/delete in certain block sizes? >>>> >>>> In these situations simply assuming 512 may slow things down. >>>> >>>> And if Solaris 11 is going to be around for a decade or so, I'd hazard to >>>> guess that 512B sector disks will become less and less prevalent as time >>>> goes on. Might as well enable the functionality now, when 4K is rarer, so >>>> you have more time to test and tunes things out?rather than later when you >>>> can potentially be left scrambling. >>>> >>>> As Pasi Kärkkäinen mentions, there's not much you can do if the disks lies >>>> (just as has been seen with disks that lie about flushing the cache). This >>>> is mostly a temporary kludge for legacy's sake. More and more disks will >>>> be truthful as times goes on. >>>> >>> >>> Most "4kB"/sector disks already today properly report both the physical >>> (4kB) and logical (512b) sector sizes. >>> It sounds like *solaris is only checking the logical (512b) sector size, >>> not the physical (4kB) sector size.. >> >> ZFS uses the physical block size. >> http://src.illumos.org/source/xref/illumos-gate/usr/src/uts/common/fs/zfs/vdev_disk.c#294 >> > > Hmm.. so everything should just work? > Does some other part of the code use logical block size then, for example to > calculate the ashift? > > Maybe I should read the code :) Or look at what your system reports :-) Though not directly intended for this use, echo ::sd_state | mdb -k and look for the un_phy_blocksize. -- richard -- ZFS and performance consulting http://www.RichardElling.com LISA '11, Boston, MA, December 4-9 _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
