Re: Speed Problem Copying Files
- Date: Mon, 13 May 2019 17:25:46 -0700
- From: David Christensen <dpchrist@xxxxxxxxxxxxxxxx>
- Subject: Re: Speed Problem Copying Files
On 5/13/19 1:30 AM, Lothar Schilling wrote:
# cat /etc/debian_version
# uname -a
Linux [my.server.com] 4.9.0-9-686-pae #1 SMP Debian 4.9.168-1
(2019-04-12) i686 GNU/Linux
As other readers have noted, you are running 32-bit Debian GNU/Linux.
It should not matter for what we're doing, but...
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3,7T 0 disk
├─sda1 8:1 0 476M 0 part /boot
├─sda2 8:2 0 93,1G 0 part /
├─sda3 8:3 0 18,6G 0 part [SWAP]
└─sda4 8:4 0 931,3G 0 part /daten
So, your boot, root, swap, and data are all on a 4 TB drive. I put my
boot, swap, and root on a small "system" disk (SSD or USB flash drive)
and my bulk data on large "data" disks (HDD; preferably RAID). Again,
it should not matter; but...
# mount | egrep 'sd[a-z]'
/dev/sda2 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/dev/sda4 on /daten type ext4 (rw,relatime,data=ordered)
/dev/sda1 on /boot type ext4 (rw,relatime,data=ordered)
# df | egrep 'sd[a-z]'
/dev/sda2 95596964 2241952 88455840 3% /
/dev/sda4 960185376 41249236 870091648 5% /daten
/dev/sda1 463826 57063 378296 14% /boot
# time dd if=/dev/urandom of=test bs=1M count=100 conv=fsync
100+0 Datensätze ein
100+0 Datensätze aus
104857600 Bytes (105 MB, 100 MiB) kopiert, 192,778 s, 544 kB/s
As you have redacted your prompt, I must assume your current working
directory was within a file system on /dev/sda?
Write performance is bad. But, now that you have a good test case for
# echo 3 > /proc/sys/vm/drop_caches && time dd if=test of=/dev/null
204800+0 Datensätze ein
204800+0 Datensätze aus
104857600 Bytes (105 MB, 100 MiB) kopiert, 0,600354 s, 175 MB/s
Read performance is questionable:
1. The file may be small enough to fit entirely within the drive cache
(e.g. 128 MB drive cache). If so, I would have expected interface speed
(e.g. ~600 MB/s for SATA 3).
2. You forgot to specify 1 megabyte blocks 'bs=1M'. dd defaults to 512
byte blocks. The drive probably uses 4 kB blocks. Small blocks reduce
performance for large files.
3. Until we figure out the write problem(s), everything else is suspect.
Consider getting a power supply tester and checking your power supply.
Computers behave very strangely when one power supply rail goes out but
the others keep working. I have an Antec, but I believe it is out of
Download a bootable memory diagnostic tool, write it to media, boot it,
and run it for at least an hour. Some people have criticized the tool I
use, so I won't make any recommendations. If the tool finds memory
problems, re-seat your memory modules and try again.
Download the diagnostic toolset from your disk drive manufacturer's web
site, write it to media/ install it (Windows may be required), and run
all the non-destructive tests. If there are problems:
* Re-seat the drive power cable and try again.
* Re-seat both ends of the drive data cable and try again.
* Substitute another drive data cable and try again.
* Use a different drive port on your motherboard or interface card and
Please reply with your findings.