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

[Stroller <stroller@stellar.eclipse.co.uk>]

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 <wwong@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..
$