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I am running a Debian 6.0.6 (before you ask). I have a regular desktop computer, nothing fancy... but when I copy a file using nautilus I am getting 10MB/s copy speed and the system is completely stuck! I did some reading and executed hdparm -tT /dev/sda with the following output:

/dev/sda:
 Timing cached reads:   2428 MB in  2.00 seconds = 1214.07 MB/sec
 Timing buffered disk reads: 274 MB in  3.01 seconds =  91.05 MB/sec

So in theory my dist is a lot faster, but in reality it is working very slow. Any ideas what could be the problem? or at least how to search for clues?

More information:

  • I've got 4GB of RAM, and I'm not running much except Chrome which seems to take half of my ram.
  • I'm copying a file from the filesystem to the same filesystem in the same drive
  • my filesystem is ext3

Update I added results from running iostat -kxdN 5 while copying to an external disk. In this case I get speeds of up to 20MB/sec, much better than local dist copy:

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
sda               4.20     6.80  265.40    2.40 26632.00    36.80   199.17     1.15    4.35   1.75  46.80
sdb               0.00  6532.00    0.00  226.20     0.00 27009.60   238.81    89.52  395.26   3.67  83.04

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
sda               1.60     3.60  230.80    1.60 26431.20    20.80   227.64     0.64    2.76   1.74  40.40
sdb              12.20  6160.00    0.60  216.80    51.20 25878.40   238.54    87.67  403.41   3.79  82.40

Anything I can learn from these numbers?

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What filesystem are you using? What is the state of the filesystem (near-full, mostly-empty)? Are you copying from and to the same filesystem or from another drive/partition? What does iostat -kxdN 1 (from package sysstat) show? Do you have enough memory/RAM available? – gertvdijk Dec 23 '12 at 20:14
@gertvdijk see my update in the question. Do you want me to run iostat when I'm copying something? because on idle it just gives me zeroes most of the time – vainolo Dec 24 '12 at 18:33
Yes, running iostat and iotop while the disk is heavily accessed, might give more details. And again: What is the state of the filesystem (near-full, mostly-empty)? If it's near-full or it has been near-full, files have been fragmented probably. Also, if memory is short it might get to swap which will kill your regular I/O operations. And note that Linux will swap earlier than it needs to usually. – gertvdijk Dec 25 '12 at 11:13
Are you using disk encryption ? LVM ? – BatchyX Jan 14 at 21:16
Not that I am aware of... Any pointers how to check? – vainolo Jan 15 at 10:20

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