On Wed, Dec 16, 2009 at 9:21 PM, Aaron Mason <simplersolut...@gmail.com>
wrote:
> On Thu, Dec 17, 2009 at 12:46 PM, Kenneth Westerback
> <kwesterb...@gmail.com> wrote:
>> On Wed, Dec 16, 2009 at 7:12 PM, Marco Peereboom <sl...@peereboom.us>
wrote:
>>> yes
>>>
>>> On Thu, Dec 17, 2009 at 12:30:46AM +0100, Robert wrote:
>>>> Hi,
>>>>
>>>> I just read [1,2] that Western Digital (and probably others) will start
>>>> to sell disks with an internal block size of 4KB instead of 512 byte.
>>>>
>>>> The article mentions that this might lead to a considerable performance
>>>> impact if the logical partition alignment is not in sync with the
>>>> physical one ("e.g. if partitions starts at sector 63 wich is not a
>>>> multiple of 4KB" [1]):
>>>> "If a block of 4KB should be written, which is (logically) aligned, but
>>>> physically in fact 2 sectors, then both physical sectors will need to be
>>>> read, partially modified and then written back which leads to a serious
>>>> performance hit." [1]
>>>>
>>>> Any comments from someone who has a good knowledge of this area? Will
>>>> this affect OpenBSD?
>>>>
>>>> regards,
>>>> Robert
>>>>
>>>> [1] (german)
>>>>
>>
http://www.heise.de/newsticker/meldung/Festplatten-mit-4-KByte-Sektorgroesse-
>> 887759.html
>>>> [2] http://www.wdc.com/wdproducts/library/whitepapers/en/2579-771430.pdf
>>>
>>>
>>
>> 4K sectors themselves should work ok as we already do that for ffs on
>> CD media. Which works the last I checked. Ensuring alignment on blocks
>> will have to be checked. It sounds like some should donate a few of
>> these 4K devices to the project so we can fix any issues asap.
>>
>> .... Ken
>>
>>
>
> I'm looking into the possibility of modifying QEMU for testing this.
> Not sure how close such things would be to reality, but it's worth a
> look in any case and would drop the cost of development significantly.
>
> --
> Aaron Mason - Programmer, open source addict
> I've taken my software vows - for beta or for worse
>
If you just want to see what you can do with/to 4K sectors, read the
vnconfig man page (-t option) and create yourself some 4K sector
devices in your disktab.
However without hardware testing you never know what the clever dicks
at the vendor have done. :-).
.... Ken
