# How can I tell linux kernel to completely ignore a disk as if it was not even connected?

Notice

Please scroll down for the answer (it has few points but it is the correct one). The problem is solved by a patch that will be in kernel 3.12.7 and up; I hope it will back-ported to earlier ones, too.

My laptop is a Samsung Chronos serie s 7. Ubuntu Gnome Remix 13.04, with Intel updated drivers.

I have a problem with the internal SSD drive (8G capacity). It fails with COMRESET and input/output errors. I am quite convinced that the problem is hardware; unfortunately I do not have Windows installed in the laptop to check if it's a matter of SSD configuration or whatever.

The problem is that the disk is recognized by udev:

KERNEL[9.515930] add      /devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sdb (block)
DEVNAME=sdb
DEVPATH=/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0/block/sdb
DEVTYPE=disk
MAJOR=8
MINOR=16
SEQNUM=1785
SUBSYSTEM=block
UDEV_LOG=3


and after that it fails in a lot of checks, delaying boot, delaying shutdown, and making (I think) suspend impossible.

Is it possible to tell Linux to completely ignore anything on the ata2 link? I tried adding this line to /etc/udev/rules.d/10-local.rules

SUBSYSTEMS=="pci"  DRIVERS=="ahci" KERNELS=="ata2" OPTIONS=="ignore_device"


but it doesn't work.

On the other hand, if anyone knows how to reset the SSD if it was left in "cache" mode without using Windows... or to boot a "live" windows to do the same...

Thanks!

Full udevadm info -a -n /dev/sdb pasted to http://paste.ubuntu.com/6186145/

smartctl -i /dev/sdb -T permissive gives:

root@samsung-romano:/home/romano# smartctl -i /dev/sdb -T permissive
smartctl 5.43 2012-06-30 r3573 [x86_64-linux-3.8.0-31-generic] (local build)
Copyright (C) 2002-12 by Bruce Allen, http://smartmontools.sourceforge.net

Vendor:               /1:0:0:0
Product:
User Capacity:        600,332,565,813,390,450 bytes [600 PB]
Logical block size:   774843950 bytes
>> Terminate command early due to bad response to IEC mode page


which is clearly wrong. Nevertheless:

root@samsung-romano:/home/romano# fdisk -b 512 -C 970 -H 256 -S 63 /dev/sdb
fdisk: unable to read /dev/sdb: Input/output error


Could all this being a side effect of the Intel Smart Response Technology not being disabled before installing Linux? If yes, how can I check it short of reinstalling a windows on the machine? Or this is a shot in the dark? (In the bios the SSD drive doesn't show and there is nothing about Intel SRT).

I changed the title of the question; I do not think that the linked question answers my problem. I positively know that the SSD is failing. I am asking if it's possible to tell the linux kernel to not probe for it at all.

• If the disk you want to hide is "sdb", could you please post the complete output of "udevadm info -a -n /dev/sdb"?. – Roman Raguet Oct 2 '13 at 20:29
• This is no duplicate of the linked question, at all. Could you please unmark it as a duplicate? I changed the title to better convey the question. Is not about an SSD check, is about a general question on disk management on Linux. Thanks! – Rmano Oct 4 '13 at 14:35
• What is the problem with just... unplugging the disk? – Braiam Oct 4 '13 at 15:34
• Similar question on Super User: How to disable kernel probing for drive? – ændrük Oct 4 '13 at 19:55
• Braiam: the SSD disk is soldered to the mainboard. – Rmano Oct 4 '13 at 20:45

Two solutions here: one is fast to apply, although solves the problem only partially, the other one is the complete one but requires you to compile your own kernel.

## The correct answer is a kernel patch.

Robin H. Johnson wrote a patch for the SATA kernel driver (find it in Unix/Linux stack exchange site) which hides completely the drive.

Update 1 The patch is now upstream (at least in 3.12.7 stable kernel), see the git repository. I asked for backport in the Ubuntu launchpad.

Update 2 The patch is in the standard kernel for Ubuntu Trusty Thar 14.04; so now only the following addition to boot parameter is needed.

Once the patch is installed, adding

 libata.force=2.00:disable


to the kernel boot parameters will hide the disk from the Linux kernel. Double check that the number is correct; searching for the device name can help:

(0)samsung-romano:~% dmesg | grep iSSD
[    1.493279] ata2.00: ATA-8: SanDisk iSSD P4 8GB, SSD 9.14, max UDMA/133
[    1.494236] scsi 1:0:0:0: Direct-Access     ATA      SanDisk iSSD P4  SSD  PQ: 0 ANSI: 5


To add a kernel parameter (bot temporarily and permanently) you can check this Q&A: How do I add a kernel boot parameter?

## Workaround

At least the problem of enabling suspend-resume has been solved by by Unix StackExchange user Emmanuel in https://unix.stackexchange.com/a/103742/52205. As root, issue the command:

echo 1 > /sys/block/sdb/device/delete


before suspend.

To make it permanent, add the following file in /etc/pm/sleep.d/ and make it executable:

-rwxr-xr-x 1 root root 204 Dec  6 16:03 99_delete_sdb


with content:

#!/bin/sh

# Delete the failing disk so that it will not block suspend

case "\$1" in
suspend|hibernate)
if [ -d /sys/block/sdb ]; then
echo 1 > /sys/block/sdb/device/delete
fi
;;
esac


...and now the system suspends (and resume) correctly.

• Thank you for reminding about /sys/block/*/device/delete. – Michael Shigorin Nov 14 '14 at 15:03
• @kikuto --- your proposed edit seemed a bit off-topic, but I added a link to how add a kernel boot parameter. Thank you. – Rmano Jan 23 '15 at 16:28

You can try to create the udev rule with the following information (output of udevadm info -a -n /dev/sdb).

INFO:

looking at parent device '/devices/pci0000:00/0000:00:1f.2/ata2/host1/target1:0:0/1:0:0:0':
KERNELS=="1:0:0:0"
SUBSYSTEMS=="scsi"
DRIVERS=="sd"
ATTRS{rev}=="SSD "
ATTRS{type}=="0"
ATTRS{scsi_level}=="6"
ATTRS{model}=="SanDisk iSSD P4 "
ATTRS{state}=="running"
ATTRS{queue_type}=="none"
ATTRS{iodone_cnt}=="0x309"
ATTRS{iorequest_cnt}=="0x30a"
ATTRS{queue_ramp_up_period}=="120000"
ATTRS{timeout}=="30"
ATTRS{evt_media_change}=="0"
ATTRS{ioerr_cnt}=="0x1d6"
ATTRS{queue_depth}=="1"
ATTRS{vendor}=="ATA     "
ATTRS{device_blocked}=="0"
ATTRS{iocounterbits}=="32"


1) Create the udev rule.

• sudo nano /etc/udev/rules.d/99-hide-ssd.rules

You can try to match the "SUBSYSTEMS" &"DRIVERS" keys, and "ATTRS{rev}" & ATTRS{model} attributes, then assign the "UDISKS" variable to ignore it.

The content of the 99-hide-ssd.rules file would be:

SUBSYSTEMS=="scsi", DRIVERS=="sd", ATTRS{rev}=="SSD ", ATTRS{model}=="SanDisk iSSD P4 ", ENV{UDISKS_IGNORE}="1"

To save the changes in nano... Ctrl+O, then Enter and finally Ctrl+X.

2) Finally refresh the udev rules with:

• sudo udevadm trigger

NOTE: With the ENV{UDISKS_IGNORE}="1" it will ignore the disk for Ubuntu 12.10 & 13.04.
For Ubuntu 12.04 the variable would be ENV{UDISKS_PRESENTATION_HIDE}="1".

Hope this helps.

• Tried it, still sdb is detected at boot (and delays it). I think should be some kernel line parameter option, but I was not able to find anything... sigh. Thanks anyway. – Rmano Oct 3 '13 at 22:44
• @Rmano... If you try to only match the kernel key?. the rule would be KERNEL=="sdb", ENV{UDISKS_IGNORE}="1"... to see if the disk is detected in udev. – Roman Raguet Oct 4 '13 at 1:26
• I know it was a lot of time ago. but this problem is still without answer... none of the suggestions worked. Thank you all anyway. – Rmano Nov 7 '13 at 17:30

As root, open up /etc/udev/rules.d/60-persistent-storage.rules with your favorite text editor.

A few lines down, you'll probably see a line that looks like this:

# skip rules for inappropriate block devices

KERNEL=="ram*|loop*|fd*|nbd*|gnbd*|dm-|md", GOTO="persistent_storage_end" Add "sdb*" to that second line, so it looks like this:

KERNEL=="ram*|loop*|fd*|nbd*|gnbd*|dm-|md|sdb*", GOTO="persistent_storage_end"

Save, reboot, and maybe it works. If not, well, is this post-warranty?

• Tried it, no luck. Still have the sdb drive, still blocking suspend. Once upon a time existed a sdb=ignore kernel command line option... And unfortunately yes, it's post-warranty. – Rmano Oct 9 '13 at 22:06
• BTW, I didn't have that file, so I added it... – Rmano Oct 9 '13 at 22:08

If your other disks are not using ahci, or aren't SSD, you may remove the kernel driver for them.

to remove for that session (until the next reboot), run:

sudo rmmod ahci


sudo modprobe ahci


if you see that everything is going fine, you now can disable it totally (don't load it next boots). open the file /etc/modprobe.d/blacklist.conf, and add the following line:

blacklist ahci


to blacklist ssd drivers, just replace ahci with sd

• That will leave me a system without any disk... the main drive is on ata1, the failing ssd on ata2. Disabling ahci mode in bios make the system unbootable... – Rmano Oct 11 '13 at 1:52

From what I know of, there is no way to remove the message, other than removing you SSD.

• Unfortunately, the SSD is (for what I know) soldered to the mainboard. It's just a 8G chip. – Rmano Oct 3 '13 at 0:14
• Cut one of the leds on the chip, preferable find the +5V line and cut that with an X-Acto? – K7AAY Oct 10 '13 at 22:57
• ...if I only knew which chip is, and where it is. Then I fear that that could create even more problems (undriven three-state...). – Rmano Oct 11 '13 at 15:24

I went and wrote a kernel patch for you that implements the ability to disable a single disk at boot time, so that you don't need to bother with disabling it in udev, or the waiting during the initial boot.

http://dev.gentoo.org/~robbat2/patches/3.13-libata-disable-disks-by-param.patch

Should apply to many kernels very easily (the line above it was added 2013-05-21/v3.10-rc1*, but can be safely applied manually without that line).