On 8 Feb 2010, at 05:25, Valmor de Almeida wrote:
Mark Knecht wrote:
On Sun, Feb 7, 2010 at 11:39 AM, Willie Wong <ww...@math.princeton.edu
> wrote:
[snip]
OK - it turns out if I start fdisk using the -u option it show me
sector numbers. Looking at the original partition put on just using
default values it had the starting sector was 63 - probably about the
I too was wondering why a Toshiba HDD 1.8" MK2431GAH (4kB-sector), 240
GB I've recently obtained was slow:
-> time tar xfj portage-latest.tar.bz2
real 16m5.500s
user 0m28.535s
sys 0m19.785s
Following your post I recreated a single partition (reiserfs 3.6)
starting at the 64th sector:
Disk /dev/sdb: 240.1 GB, 240057409536 bytes
255 heads, 63 sectors/track, 29185 cylinders, total 468862128 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0xe7bf4b8e
Device Boot Start End Blocks Id System
/dev/sdb1 64 468862127 234431032 83 Linux
and the time was improved
-> time tar xfj portage-latest.tar.bz2
real 2m15.600s
user 0m28.156s
sys 0m18.933s
Thanks to both you & Mark for posting this information about these
improved timings.
I have just checked, and I am getting 3.5 - 6 minutes (real) to untar
portage. I had blamed performance of this array on the fact that the
RAID controller is an older model PCI card I got cheap(ish) off eBay,
but I see it is also aligned beginning at sector 63.
I'm not quite sure if this is cause of poor performance here, as the
drives in this array are not quite as modern as yours - I'm guessing
that at least a couple of the drives have been bought in the last 6
months, but they are only 500GB drives. However I guess it would only
require one drive in the array to have 4K sectors and it would cause
this kind of slowdown. I will try checking their spec now.
This is the same server that caused me to post in relation to slow
Samba transfers 3 weeks ago ("How to determine if a NIC is playing
gigabit?"). I have still not yet tested thoroughly - there are always
chores getting in the way! - but it seems like I was able to transfer
the same files in about a third (or maybe even a quarter) the time at
100mbit, between my laptop & desktop Macs.
I am not immediately able to alter the partition layout, as I have
scads of data on this array. In order to test I think I will need to
create a second array, aligned optimally, and copy the data across.
I had been recently thinking that 2TB drives are now 40% cheaper per
gig than 500GB ones, so perhaps I will have to splash out on 3 of
them. This seems rather a lot of money, but I could probably use the
space. Hmmmn... actually 1TB are nearly as cheap as per gig -
considering the eBaying of my current drives, those would make a lot
of sense.
Stroller.
$ time tar xfj portage-latest.tar.bz2
real 6m3.128s
user 0m37.810s
sys 0m39.614s
$ echo p | sudo fdisk -u /dev/sdb
The number of cylinders for this disk is set to 182360.
There is nothing wrong with that, but this is larger than 1024,
and could in certain setups cause problems with:
1) software that runs at boot time (e.g., old versions of LILO)
2) booting and partitioning software from other OSs
(e.g., DOS FDISK, OS/2 FDISK)
Command (m for help):
Disk /dev/sdb: 1500.0 GB, 1499968045056 bytes
255 heads, 63 sectors/track, 182360 cylinders, total 2929625088 sectors
Units = sectors of 1 * 512 = 512 bytes
Disk identifier: 0x27a827a7
Device Boot Start End Blocks Id System
/dev/sdb1 63 2929613399 1464806668+ 83 Linux
Command (m for help): Command (m for help): Command (m for help):
got EOF thrice - exiting..
$
