Ubuntu
linux package

slow raw writing to partition because of read access

Bug #182158 reported by Michael Trunner
2
Affects Status Importance Assigned to Milestone
linux (Ubuntu)
Invalid
Undecided
Unassigned

Bug Description

Binary package hint: linux-image

I tried to copy a partition images over the network with nc and dd.
On my partition sda9 it was very fast about 55 Mb/s. On the sda2 I had only 8 Mb/s.

With dstat I found the reason: When writing data to the sda2, the kernel reads the same amount of data that it is writing.
On partition sda9 there was nearly no read disk access.

The problem exist even in init 1, so I think it is a kernel problem. Inotify was off.

I used the followoing commands:

client:

nc -l -p 19000 | dd of=/dev/sda2
or
nc -l -p 19000 > /dev/sda2 (makes no difference)

server:

dd if=/dev/sda2 | nc targethost 19000

It tried the same with different computers on my laptop some partitions have the same problem.
Any Ideas?

Revision history for this message
Leann Ogasawara (leannogasawara) wrote :

[This is an automated message. Apologies if it has reached you inappropriately.]

This bug was reported against the linux-meta package when it likely should have been reported against the linux package instead. We are automatically transitioning this to the linux kernel package so that the appropriate teams are notified and made aware of this issue. Thanks.

affects: linux-meta (Ubuntu) → linux (Ubuntu)
Revision history for this message
kernel-janitor (kernel-janitor) wrote :

Hi trunner,

Please be sure to confirm this issue exists with the latest development release of Ubuntu. ISO CD images are available from http://cdimage.ubuntu.com/releases/ . Please then run following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux-image-`uname -r` 182158

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

tags: added: needs-kernel-logs
tags: added: needs-upstream-testing
tags: added: kj-triage
Changed in linux (Ubuntu):
status: New → Incomplete
Revision history for this message
Jeremy Foshee (jeremyfoshee) wrote :

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release http://www.ubuntu.com/getubuntu/download . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]

tags: added: kj-expired
Changed in linux (Ubuntu):
status: Incomplete → Invalid
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