All of lore.kernel.org
 help / color / mirror / Atom feed
From: Neil Brown <neilb@suse.de>
To: Zoltan Szecsei <zoltans@geograph.co.za>
Cc: linux-raid@vger.kernel.org
Subject: Re: Array read 3 time slower to read after data fully loaded
Date: Mon, 22 Nov 2010 15:18:16 +1100	[thread overview]
Message-ID: <20101122151816.6ed89c4b@notabene.brown> (raw)
In-Reply-To: <4CE4B9E6.1040802@geograph.co.za>

On Thu, 18 Nov 2010 07:30:14 +0200
Zoltan Szecsei <zoltans@geograph.co.za> wrote:

> Hi,
> Can anyone please explain this to me?
> 
> For the last >30 hours I have been loading some 2.5TB of 200-400MB tiff 
> images, from another PC on our internal network, onto this new array.
> Yesterday, during this load process, I copied 10 of these files (about 
> 2.5GB) from the array onto the /home directory of the same system.
> 
> It took 33 seconds, equating to some 75MB/s.
> 
> This morning I came in to find that the load process had finished, so I 
> deleted the 10 test files from /home, and redid the identical copy test 
> (using bash-history, so: identical).
> 
> It took 123 seconds, equating to some 20MB/s.
> 
> Que? (as in Manuel from Faulty Towers :-)  )

Maybe the first time some of the files were in RAM... how much RAM do you
have, and how recently that the files been loaded before your copied them?

NeilBrown - who has never been to Barcelona.

> 
> 
> Thanks & regards,
> Zoltan
> 
> 
> root@gs0:/home/geograph# uname -a
> Linux gs0 2.6.32-25-generic #45-Ubuntu SMP Sat Oct 16 19:52:42 UTC 2010 
> x86_64 GNU/Linux
> root@gs0:/home/geograph# mdadm -V
> mdadm - v3.1.4 - 31st August 2010
> root@gs0:/home/geograph# lvm version
>    LVM version:     2.02.54(1) (2009-10-26)
>    Library version: 1.02.39 (2009-10-26)
>    Driver version:  4.15.0
> root@gs0:/home/geograph# df  #ext4
> Filesystem           1K-blocks      Used Available Use% Mounted on
> /dev/sdi7            426559760   9494844 395396872   3% /home
> /dev/mapper/geo_vg0-geo_lvm0
>                       11536635672 2530042680 8889387468  23% /mnt/geo_lvm0
> root@gs0:/home/geograph#
> 
> 


      parent reply	other threads:[~2010-11-22  4:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-11-18  5:30 Array read 3 time slower to read after data fully loaded Zoltan Szecsei
2010-11-18 20:43 ` Michal Soltys
2010-11-18 20:53   ` David Lethe
2010-11-22  4:18 ` Neil Brown [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20101122151816.6ed89c4b@notabene.brown \
    --to=neilb@suse.de \
    --cc=linux-raid@vger.kernel.org \
    --cc=zoltans@geograph.co.za \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.