Re: [gentoo-user] 1-Terabyte drives - 4K sector sizes? -> bar performance so far

[Volker Armin Hemmann <volkerarmin@googlemail.com>]

On Sonntag 07 Februar 2010, Mark Knecht wrote:
> On Sun, Feb 7, 2010 at 9:30 AM, Alexander <b3nder@yandex.ru> wrote:
> > On Sunday 07 February 2010 19:27:46 Mark Knecht wrote:
> >>    Every time there is an apparent delay I just see the hard drive
> >> light turned on solid. That said as far as I know if I wait for things
> >> to complete the data is there but I haven't tested it extensively.
> >> 
> >>    Is this a bad drive or am I somehow using it incorrectly?
> > 
> > Is there any related info in dmesg?
> 
> No, nothing in dmesg at all.
> 
> Here are two tests this morning. The first is to the 1T drive, the
> second is to a 120GB drive I'm currently using as a system drive until
> I work this out:
> 
> gandalf TestMount # time tar xjf /mnt/TestMount/portage-latest.tar.bz2
> -C /mnt/TestMount/usr
> 
> real	8m13.077s
> user	0m8.184s
> sys	0m2.561s
> gandalf TestMount #
> 
> 
> mark@gandalf ~ $ time tar xjf /mnt/TestMount/portage-latest.tar.bz2 -C
> /home/mark/Test_usr/
> 
> real	0m39.213s
> user	0m8.243s
> sys	0m2.135s
> mark@gandalf ~ $
> 
> 8 minutes vs 39 seconds!
> 
> The amount of data written appears to be the same:
> 
> gandalf ~ # du -shc /mnt/TestMount/usr/
> 583M	/mnt/TestMount/usr/
> 583M	total
> gandalf ~ #
> 
> 
> mark@gandalf ~ $ du -shc /home/mark/Test_usr/
> 583M	/home/mark/Test_usr/
> 583M	total
> mark@gandalf ~ $
> 
> 
> I did some reading at the WD site and it seems this drive does use the
> 4K sector size. The way it's done is the addressing on cable is still
> 512 byte 'user sectors', but they are packed into 4K physical sectors
> and internal hardware does the mapping.
> 
> I suspect the performance issue is figuring out how to get the file
> system to keep things on 4K boundaries. I assume that's what the 4K
> block size is for when building the file system but I need to go find
> out more about that. I did not select it specifically. Maybe I need
> to.
> 
> Thanks,
> Mark

no. 4k block size is the default for linux filesystems. But you might have 
'misaligned' the partitions. There is a lot of text to read about 
'eraseblocks' on ssds and how important it is to align the partitions. You 
might want to read up on that to learn how to align partitions.