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

[Frank Steinmetzger <Warp_7@gmx.de>]

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Am Dienstag, 9. Februar 2010 schrieb Frank Steinmetzger:

> > 4) Everything I've done so far leave me with messages about partition
> > 1 not ending on a cylinder boundary. Googling on that one says don't
> > worry about it. I don't know...

Well since only the start of a partition determines its alignment with 
hardware sectors, I think it's really not that important. Worst case: mkfs 
truncates the last few sectors to make it a multiple of its cluster size.

> Anyway, mine's like this, just to throw it into the pot to the others
> ( those # are added by me to show their respective use )
>
> eisen # fdisk -l -u /dev/sda
>
> Disk /dev/sda: 500.1 GB, 500107862016 bytes
> 255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Disk identifier: 0x80178017
>
>    Device Boot     Start         End      Blocks   Id  System
> /dev/sda1   *         63    25157789    12578863+   7  HPFS/NTFS # Windows
> /dev/sda2       25157790    88084394    31463302+   7  HPFS/NTFS # Games
> /dev/sda3       88084395   127941659    19928632+  83  Linux     # / 
> /dev/sda4      127941660   976768064   424413202+   5  Extended
> /dev/sda5      127941723   288816569    80437423+  83  Linux     # /home
> /dev/sda6      288816633   780341309   245762338+  83  Linux     # music
> /dev/sda7      813113973   976703804    81794916   83  Linux     # X-Plane
> /dev/sda8   *  976703868   976768064       32098+  83  Linux     #
> /boot /dev/sda9      780341373   813113909    16386268+   7  HPFS/NTFS #
> Win7 test

I have started amending my partitioning scheme, starting at the rear. Since my 
backup drive has exactly the same scheme, I’m working on that and then 
restore my local drive from it, so I need as little time in a LiveCD 
environment as possible.

I have reset sdb7 to use boundaries divisible by 64.
Old range            begin%64  size%64  New range            begin%64  size%64
813113973-976703804  0.8281    0.125    813113984-976703935  0         0

And guess what - the speed of truecrypt at creating a new container doubled. 
With the old scheme, it started at 13.5 MB/s, now it started at 26-odd. I’m 
blaming that cap on the USB connection to the drive, though it’s gradually 
getting more: after 2/3 of the partition, it’s at 27.7.

So sdb7 now ends at sector 976703935. Interestingly, I couldn’t use the 
immediate next sector for sdb8:
start for sdb8   response by fdisk
976703936        sector already allocated
976703944        Value out of range. First sector... (default 976703999):

The first one fdisk offered me was exactly 64 sectors behind the end sector of 
sdb7 (976703999), which would leave a space of those mysterious 62 “empty” 
sectors in between. So I used 976704000, which is divisable by 64 again, 
though it’s not that relevant for a partition of 31 MB. :D

As soon as truecrypt is finished, I'm going to solidify my findings by 
performing this on another partition, and I’ll also see what happens if I 
start at a start sector of k*64+1. Just out of curiousity. :-)
-- 
Gruß | Greetings | Qapla'
Crayons can take you more places than starships. (Guinan)

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