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What do these errors mean?

Sep 30 23:52:29 ubuntu kernel: [ 1649.816032] [Hardware Error]: Machine check events logged
Sep 30 23:52:37 ubuntu kernel: [ 1657.885240] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:52:37 ubuntu kernel: [ 1657.887489] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:52:37 ubuntu kernel: [ 1657.887495] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:53:29 ubuntu kernel: [ 1709.597129] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:53:29 ubuntu kernel: [ 1709.599380] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:53:29 ubuntu kernel: [ 1709.599385] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:54:21 ubuntu kernel: [ 1761.309135] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:54:21 ubuntu kernel: [ 1761.311386] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:54:21 ubuntu kernel: [ 1761.311391] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:55:04 ubuntu AptDaemon: INFO: Quitting due to inactivity
Sep 30 23:55:04 ubuntu AptDaemon: INFO: Quitting was requested
Sep 30 23:55:04 ubuntu dbus[881]: [system] Activating service name='org.debian.apt' (using servicehelper)
Sep 30 23:55:05 ubuntu AptDaemon: INFO: Initializing daemon
Sep 30 23:55:05 ubuntu dbus[881]: [system] Successfully activated service 'org.debian.apt'
Sep 30 23:55:05 ubuntu AptDaemon.PackageKit: INFO: Initializing PackageKit compat layer
Sep 30 23:55:12 ubuntu kernel: [ 1813.021139] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:55:12 ubuntu kernel: [ 1813.023394] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:55:12 ubuntu kernel: [ 1813.023399] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:56:04 ubuntu kernel: [ 1864.737157] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:56:04 ubuntu kernel: [ 1864.739403] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:56:04 ubuntu kernel: [ 1864.739408] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:56:56 ubuntu kernel: [ 1916.453416] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:56:56 ubuntu kernel: [ 1916.455780] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:56:56 ubuntu kernel: [ 1916.455786] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:57:47 ubuntu kernel: [ 1968.157063] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:57:47 ubuntu kernel: [ 1968.159297] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:57:47 ubuntu kernel: [ 1968.159303] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:58:39 ubuntu kernel: [ 2019.869064] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:58:39 ubuntu kernel: [ 2019.871307] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:58:39 ubuntu kernel: [ 2019.871312] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:59:31 ubuntu kernel: [ 2071.581322] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Sep 30 23:59:31 ubuntu kernel: [ 2071.586202] sd 6:0:0:0: [sdb] Asking for cache data failed
Sep 30 23:59:31 ubuntu kernel: [ 2071.586208] sd 6:0:0:0: [sdb] Assuming drive cache: write through
Sep 30 23:59:41 ubuntu wpa_supplicant[1223]: WPA: Group rekeying completed with 00:24:b2:dd:cb:42 [GTK=CCMP]
Oct  1 00:00:05 ubuntu AptDaemon: INFO: Quitting due to inactivity
Oct  1 00:00:05 ubuntu AptDaemon: INFO: Quitting was requested
Oct  1 00:00:05 ubuntu dbus[881]: [system] Activating service name='org.debian.apt' (using servicehelper)
Oct  1 00:00:06 ubuntu AptDaemon: INFO: Initializing daemon
Oct  1 00:00:06 ubuntu dbus[881]: [system] Successfully activated service 'org.debian.apt'
Oct  1 00:00:06 ubuntu AptDaemon.PackageKit: INFO: Initializing PackageKit compat layer
Oct  1 00:00:23 ubuntu kernel: [ 2123.293360] sd 6:0:0:0: [sdb] Test WP failed, assume Write Enabled
Oct  1 00:00:23 ubuntu kernel: [ 2123.295625] sd 6:0:0:0: [sdb] Asking for cache data failed
Oct  1 00:00:23 ubuntu kernel: [ 2123.295630] sd 6:0:0:0: [sdb] Assuming drive cache: write through
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I noticed [Hardware Error]: Machine check events logged. These machine errors aren't logged by default - please install the mcelog package and see the log file in /var/log/mcelog. It should provide some details about the first line you're seeing. This is certainly hardware related. –  gertvdijk Aug 27 '13 at 8:34
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5 Answers 5

"Test WP failed, assume Write Enabled" means that the SCSI layer could not read the write protect status so after some different kinds of probing gave up and assumes the device has write enable set. It's in the kernel in function sd_read_write_protect_flag(), drivers/scsi/sd.c - and it's nothing to worry about.

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Many people have a Realtek multicard reader. It's driver causes such messages. If you have such and you don't use it, you may remove it's driver from the running kernel with:

$sudo rmmod ums_realtek

It'll be back after reboot. In this thread: Constant warnings from the kernel, Mr. Krzysztof Kosinski proposed the following solution:

create the file

/etc/modprobe.d/ums-realtek.conf

with the following content:

options ums_realtek ss_en=0

You can do it with this command:

sudo sh -c 'echo "options ums_realtek ss_en=0" > /etc/modprobe.d/ums-realtek.conf'

Explanation: The 'ss_en' switch controls 'selective suspend', e.g. suspending parts of the card reader which are not used. When there is no card, the reader would power down through the normal USB suspend mechanism.

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Is there a problem? Why do you assume these are errors? Obviously, most of what is there is not an error; I would assume these are simply status messages output during normal operation. The process seems to be saying that it checked to see if Write Protect was enabled, and did not find any indication that it was, so it is assuming not (Write Enabled), and therefore it is OK to write to the device (sdb).

If there was an error, it would have said so.

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First line: [Hardware Error]: Machine check events logged This is usually quite serious. –  gertvdijk Aug 27 '13 at 8:33
    
In my experience, low-level errors without any context are not something to worry about, and are often expected. I've done a lot of hardware programming, and often the only way to test a capability is to try it and see if it fails. As long as the failure is not harmful, this is a valid method of testing. So, your saying "usually quite serious" is not useful: either it is serious or not, and if you don't know, don't pretend you do. –  Marty Fried Aug 27 '13 at 19:55
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I had same problem on my laptop and I was surprised because i do not have any additional disks USB or any thing

after checking the pc i found that I was connecting the empty SD-MEM converter to SD reader I just unplugged it the error disappeared

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While this is indeed factually correct, the OP and future visitors should remember that this is not the only explanation. –  hexafraction Nov 29 '12 at 0:25
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I had this same problem. It should be noted that some laptops come with little plastic inserts that fit inside the SD reader. Linux will think this is an actual sd card and attempt to auto-access it like it does with USB drives.

make sure that there is nothing in the sd card reader. That's what happened to me.

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