Date: Wed, 17 Mar 2010 19:12:01 +0100 From: Olivier Smedts <olivier@gid0.org> To: Thiago Damas <tdamas@gmail.com> Cc: =?ISO-8859-1?Q?Dag=2DErling_Sm=F8rgrav?= <des@des.no>, Mohacsi Janos <mohacsi@niif.hu>, freebsd-hackers@freebsd.org Subject: Re: ATA 4K sector issues Message-ID: <367b2c981003171112n785ea9d4q21d00b533819ca67@mail.gmail.com> In-Reply-To: <f8e3d83f1003171034m5e75eae4r5e8b31d88d361d3b@mail.gmail.com> References: <alpine.BSF.2.00.1003171114280.74067@mignon.ki.iif.hu> <86tysf58a2.fsf@ds4.des.no> <alpine.BSF.2.00.1003171652260.74067@mignon.ki.iif.hu> <f8e3d83f1003171034m5e75eae4r5e8b31d88d361d3b@mail.gmail.com>
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2010/3/17 Thiago Damas <tdamas@gmail.com>:
> =A0I had problem with ZFS.
> =A0With gnop -S 4096, it works well on /dev/ad{a}X.nop; but I decided to =
not
> use those disks.
So maybe this was not a ZFS problem but a partition misalignment problem ?
On a properly aligned partition with a physical sector size of 4KB and
a logical sector size of 512 bytes, will ZFS try to use blocksizes of
less than 4KB ? Blocksize in ZFS seems to be dynamic (at least when
not told to use a fixed blocksize), but I didn't see somewhere in the
manpage or Sun's website which minimum blocksize ZFS would use for
small files, and if there is a lower limit on blocksizes to use.
>
>
> 2010/3/17 Mohacsi Janos <mohacsi@niif.hu>
>
>>
>>
>>
>> On Wed, 17 Mar 2010, Dag-Erling Sm?rgrav wrote:
>>
>> =A0Mohacsi Janos <mohacsi@niif.hu> writes:
>>>
>>>> What is the situation with ATA 4K dirves in FreeBSD? Are there
>>>> any support for them in fdisk or disklabel?
>>>>
>>>
>>> Hmm, didn't we discuss this already? =A0All we need to do is change the
>>> defaults in fdisk so it rounds partition offsets and sizes to a multipl=
e
>>> of 8 sectors (or 16 for future-proofing) instead of aligning them with
>>> fictitious cylinder boundaries. =A0Bsdlabel, as disklabel is properly
>>> known, already DTRT: by default, the first partition starts at offset
>>> 16. =A0Just make sure you specify sizes that are divisible by 8 or 16
>>> blocks (not an issue if you use the M or G suffixes). =A0Sysinstall
>>> operates in megabytes.
>>>
>>
>> Thanks for the information.
>>
>>
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