Date: Mon, 22 Aug 2011 12:45:08 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-hackers@freebsd.org Subject: Re: ZFS installs on HD with 4k physical blocks without any warning as on 512 block size device Message-ID: <j2tbvk$k1q$1@dough.gmane.org> In-Reply-To: <CAO1bj=ZHC0ZMtrQKr3DV8E3rP3gTMHxdF3J2EPAD3wR5dqN%2BkA@mail.gmail.com> References: <4E4D50CD.5080806@rawbw.com> <CAFHbX1K%2BRuzBKouAbN0%2BSCOSAkGNdgMzC92YN7GeKn_pD=J=tg@mail.gmail.com> <CAO1bj=ZHC0ZMtrQKr3DV8E3rP3gTMHxdF3J2EPAD3wR5dqN%2BkA@mail.gmail.com>
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On 19/08/2011 14:21, Aled Morris wrote: > On 19 August 2011 11:15, Tom Evans<tevans.uk@googlemail.com> wrote: > >> On Thu, Aug 18, 2011 at 6:50 PM, Yuri<yuri@rawbw.com> wrote: >>> Some latest hard drives have logical sectors of 512 byte when they >> actually >>> have 4k physical sectors. >> > ... >> Shouldn't UFS and ZFS drivers be able to either read the right sector size > >>> from the underlying device or at least issue a warning? >> >> The device never reports the actual sector size, so unless FreeBSD >> keeps a database of 4k sector hard drives that report as 512 byte >> sector hard drives, there is nothing that can be done. >> > At what point should we change the default in newfs/zfs to 4k? It is already changed for UFS in 9. > I guess formatting the filesystem for 4k sectors on a 512b drive would still > work but it would be suboptimal. What would the performance penalty be in > reality? It would be suboptimal but only for the slight waste of space that would have otherwise been reclaimed if the block or fragment size remained 512 or 2K. This waste of space is insignificant for the vast majority of users and there are no performance penalties, so it seems that switching to 4K sectors by default for all file systems would actually be a good idea.
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