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From: Zoltan Szecsei <zoltans@geograph.co.za>
To: linux-raid@vger.kernel.org
Subject: Array read 3 time slower to read after data fully loaded
Date: Thu, 18 Nov 2010 07:30:14 +0200	[thread overview]
Message-ID: <4CE4B9E6.1040802@geograph.co.za> (raw)

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 :-)  )


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#


-- 

===========================================
Zoltan Szecsei PrGISc [PGP0031]
Geograph (Pty) Ltd.
P.O. Box 7, Muizenberg 7950, South Africa.

65 Main Road, Muizenberg 7945
Western Cape, South Africa.

34° 6'16.35"S 18°28'5.62"E

Tel: +27-21-7884897  Mobile: +27-83-6004028
Fax: +27-86-6115323     www.geograph.co.za
===========================================



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             reply	other threads:[~2010-11-18  5:30 UTC|newest]

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

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