Posts Tagged ‘filesystems’

How to mount NTFS Windows XP filesystem on FreeBSD, NetBSD, OpenBSD

Friday, May 11th, 2012

Mounting NTFS hdd partitions on FreeBSD logo picture

A friend of mine bring home a Seagate External Hard Disk Drive using USB 3 as a communication media. I needed to attach the hard disk to my FreeBSD router to transfer him some data, the External HDD is formatted to use NTFS as a main file partition and hence to make the file transfers I had to somehow mount the NTFS partition on the HDD.

FreeBSD and other BSDs, just like Linux does not have embedded NTFS file system mount support.
In order to add an external write support for the plugged hdd NTFS I looked in the ports tree:

freebsd# cd /usr/ports
freebsd# make search name='ntfs'
Port: fusefs-ntfs-2010.10.2
Path: /usr/ports/sysutils/fusefs-ntfs
Info: Mount NTFS partitions (read/write) and disk images
Maint: ports@FreeBSD.org
B-deps: fusefs-libs-2.7.4 libiconv-1.13.1_1 libtool-2.4 libublio-20070103 pkg-config-0.25_1
R-deps: fusefs-kmod-0.3.9.p1.20080208_7 fusefs-libs-2.7.4 libiconv-1.13.1_1 libublio-20070103 pkg-config-0.25_1
WWW: http://www.tuxera.com/community/

Port: ntfsprogs-2.0.0_1
Path: /usr/ports/sysutils/ntfsprogs
Info: Utilities and library to manipulate NTFS partitions
Maint: ports@FreeBSD.org
B-deps: fusefs-libs-2.7.4 libiconv-1.13.1_1 libublio-20070103 pkg-config-0.25_1
R-deps: libublio-20070103 pkg-config-0.25_1
WWW: http://www.linux-ntfs.org/
freebs# cd sysutils/fusefs-ntfs/
freebsd# ls
Makefile distinfo files/ pkg-descr pkg-plist
freebsd# cat pkg-descr
The ntfs-3g driver is an open source, freely available read/write NTFS
driver, which provides safe and fast handling of the Windows XP, Windows
Server 2003 and Windows 2000 filesystems. Almost the full POSIX filesystem
functionality is supported, the major exceptions are changing the file
ownerships and the access rights.
WWW: http://www.tuxera.com/community/

Using ntfs-3g I managed to succeed mounting the NTFS on my old PC running FreeBSD ver. 7_2

1. Installing fuserfs-ntfs support on BSD

Before I can use ntfs-3g, to mount the paritition, I had to install fuserfs-ntfs bsd port, with:

freebsd# cd /usr/ports/sysutils/fusefs-ntfs
freebsd# make install clean
.....

I was curious if ntfsprogs provides other utilities to do the ntfs mount but whilst trying to install it I realized it is already installed as a dependency package to fusefs-ntfs.

fusefs-ntfs package provides a number of utilities for creating, mounting, fixing and doing various manipulations with Microsoft NTFS filesystems.

Here is a list of all the executable utilities helpful in NTFS fs management:

freebsd# pkg_info -L fusefs-ntfs\* | grep -E "/bin/|/sbin|README"
/usr/local/bin/lowntfs-3g
/usr/local/bin/ntfs-3g
/usr/local/bin/ntfs-3g.probe
/usr/local/bin/ntfs-3g.secaudit
/usr/local/bin/ntfs-3g.usermap
/usr/local/bin/ntfscat
/usr/local/bin/ntfscluster
/usr/local/bin/ntfscmp
/usr/local/bin/ntfsfix
/usr/local/bin/ntfsinfo
/usr/local/bin/ntfsls
/usr/local/sbin/mkntfs
/usr/local/sbin/ntfsclone
/usr/local/sbin/ntfscp
/usr/local/sbin/ntfslabel
/usr/local/sbin/ntfsresize
/usr/local/sbin/ntfsundelete
/usr/local/share/doc/ntfs-3g/README
/usr/local/share/doc/ntfs-3g/README.FreeBSD

The README and README.FreeBSD are wonderful, reading for those who want to get more in depth knowledge on using the up-listed utilities.

One utility, worthy to mention, I have used in the past is ntfsfix. ntfsfix resolve issues with NTFS partitions which were not unmounted on system shutdown (electricity outage), system hang up etc.

2. Start fusefs (ntfs) and configure it to auto load on system boot

Once fuserfs-ntfs is installed, if its necessery ntfs fs mounts to be permanently supported on the BSD system add fusefs_enable="YES" to /etc/rc.conf(the FreeBSD services auto load conf).

freebsd# echo 'fusefs_enable="YES"' >> /etc/rc.conf

One note to make here is that you need to have also dbus_enable="YES" and hald_enable="YES" in /etc/rc.conf, not having this two in rc.conf will prevent fusefs to start properly. Do a quick grep to make sure this two variables are enabled:

Afterwards fsusefs load up script should be run:

freebsd# /usr/local/etc/rc.d/fusefs start
Starting fusefs.

Another alternative way to load ntfs support on the BSD host is to directly load fuse.ko kernel module:

freebsd# /sbin/kldload fuse.ko

3. Mounting the NTFS partition

In my case, the Seagate hard drive was detected as da0, where the NTFS partition was detected as s1 (da0s1):

freebsd# dmesg|grep -i da0
da0 at umass-sim0 bus 0 target 0 lun 0
da0: Fixed Direct Access SCSI-4 device
da0: 40.000MB/s transfers
da0: 953869MB (1953525164 512 byte sectors: 255H 63S/T 121601C)br />GEOM_LABEL: Label for provider da0s1 is ntfs/Expansion Drive.
GEOM_LABEL: Label for provider da0s1 is ntfs/Expansion Drive.

Therefore further to mount it one can use mount_ntfs (to quickly mount in read only mode) or ntfs-3g for (read / write mode):

If you need to just quickly mount a disk drive to copy some data and umount it with no need for writting to the NTFS partition do;

freebsd# /sbin/mount_ntfs /dev/ad0s1 /mnt/disk

Note that mount_ntfs command is a native BSD command and have nothing to do with ntfs-3g. Therefore using it to mount NTFS is not the same as mounting it via ntfs-3g cmd

freebsd# /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

Something, I've noticed while using ntfs-3g is, it fails to properly exit even when the ntfs-3g shell execution is over:

freebsd# ps ax |grep -i ntfs|grep -v grep
18892 ?? Is 0:00.00 /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

I dunno if this is some kind of ntfs-3g bug or feature specific to all versions of FreeBSD or it is something local to FBSD 7.2

Thought ntfs-3g, keeps appearing in process list, praise God as of time of writting NTFS support on FreeBSD prooved to be stable.
Read / Write disk operations to the NTFS I tested it with works great. Just about 5 years ago I still remember write mode was still experimental. Now it seems NTFS mounts can be used with no hassle even on production machines.

4. Auto mounting NTFS partition on FreeBSD system boot

There are two approaches towards 'the problem' I can think of.
The better way to auto mount on boot (in my view) is through /etc/fstab use

If /etc/fstab + ntfs-3g is to be used, you will however change the default /sbin/mount_ntfs command to point to /usr/local/bin/ntfs-3g, i.e.:

freebsd# mv /sbin/mount_ntfs /sbin/mount_ntfs.orig
freebsd# ln -s /usr/local/bin/ntfs-3g /sbin/mount_ntfs

Then to mount /dev/da0s1 via /etc/fstab add line:

/dev/ad0s1 /mnt/disk ntfs rw,late 0 0

To not bother with text editor run:

freebsd# echo '/dev/ad0s1 /mnt/disk ntfs rw,late 0 0' >> /etc/fstab

I've red in posts in freebsd forums, there is also a way to use ntfs-3g for mounting partitions, without substituting the original bsd /sbin/mount_ntfs, the exact commands suggested to be used with no need to prior mv /sbin/mount_ntfs to /sbin/mount_ntfs.orig and link it to ntfs is:

/dev/ad0s1 /disk ntfs rw,mountprog=/usr/local/bin/ntfs-3g,late 0 0

For any other NTFS partitions, for instance /dev/ad0s2, /dev/ad2s1 etc. simply change the parititon name and mount points.

The second alternative to adding the NTFS to auto mount is through /etc/rc.local. /etc/rc.local content will be executed very late in system boot. :

echo '/usr/local/bin/ntfs-3g -o rw /dev/da0s1' >> /etc/rc.local

One disadvanage of using /etc/rc.local for mounting the partition is the hanging ntfs-3g in proc list:

freebsd# ps ax |grep -i ntfs|grep -v grep
18892 ?? Is 0:00.00 /usr/local/bin/ntfs-3g -o rw /dev/da0s1 /mnt/disk/

Though, I haven't tested it yet. Using the same methodology should be perfectly working on PC-BSD, DragonFlyBSD, NetBSD and OpenBSD.
I will be glad if someone who runs any of the other BSDs can confirm, following this instructions works fine on these BSDs too.

How to reboot remotely Linux server if reboot, shutdown and init commands are not working (/sbin/reboot: Input/output error) – Reboot Linux in emergency using MagicSysRQ kernel sysctl variable

Saturday, July 23rd, 2011

SysRQ an alternative way to restart unrestartable Linux server

I’ve been in a situation today, where one Linux server’s hard drive SCSI driver or the physical drive is starting to break off where in dmesg kernel log, I can see a lot of errors like:

[178071.998440] sd 0:0:0:0: [sda] Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK,SUGGEST_OK
[178071.998440] end_request: I/O error, dev sda, sector 89615868

I tried a number of things to remount the hdd which was throwing out errors in read only mode, but almost all commands I typed on the server were either shown as missng or returning an error:
Input/output error

Just ot give you an idea what I mean, here is a paste from the shell:

linux-server:/# vim /etc/fstab
-bash: vim: command not found
linux-server:/# vi /etc/fstab
-bash: vi: command not found
linux-server:/# mcedit /etc/fstab
-bash: /usr/bin/mcedit: Input/output error
linux-server:/# fdisk -l
-bash: /sbin/fdisk: Input/output error

After I’ve tried all kind of things to try to diagnose the server and all seemed failing, I thought next a reboot might help as on server boot the filesystems will get checked with fsck and fsck might be able to fix (at least temporary) the mess.

I went on and tried to restart the system, and guess what? I got:

/sbin/reboot init Input/output error

I hoped that at least /sbin/shutdown or /sbin/init commands might work out and since I couldn’t use the reboot command I tried this two as well just to get once again:

linux-server:/# shutdown -r now
bash: /sbin/shutdown: Input/output error
linux-server:/# init 6
bash: /sbin/init: Input/output error

You see now the situation was not pinky, it seemed there was no way to reboot the system …
Moreover the server is located in remote Data Center and I the tech support there is conducting assigned task with the speed of a turtle.
The server had no remote reboot, web front end or anything and thefore I needed desperately a way to be able to restart the machine.

A bit of research on the issue has led me to other people who experienced the /sbin/reboot init Input/output error error mostly caused by servers with failing hard drives as well as due to HDD control driver bugs in the Linux kernel.

As I was looking for another alternative way to reboot my Linux machine in hope this would help. I came across a blog post Rebooting the Magic Wayhttp://www.linuxjournal.com/content/rebooting-magic-way

As it was suggested in Cory’s blog a nice alternative way to restart a Linux machine without using reboot, shutdown or init cmds is through a reboot with the Magic SysRQ key combination

The only condition for the Magic SysRQ key to work is to have enabled the SysRQ – CONFIG_MAGIC_SYSRQ in Kernel compile time.
As of today luckily SysRQ Magic key is compiled and enabled by default in almost all modern day Linux distributions in this numbers Debian, Fedora and their derivative distributions.

To use the sysrq kernel capabilities as a mean to restart the server, it’s necessery first to activate the sysrq through sysctl, like so:

linux-server:~# sysctl -w kernel.sysrq=1
kernel.sysrq = 1

I found enabling the kernel.sysrq = 1 permanently in the kernel is also quite a good idea, to achieve that I used:

echo 'kernel.sysrq = 1' >> /etc/sysctl.conf

Next it’s wise to use the sync command to sync any opened files on the server as well stopping as much of the server active running services (MySQL, Apache etc.).

linux-server:~# sync

Now to reboot the Linux server, I used the /proc Linux virtual filesystem by issuing:

linux-server:~# echo b > /proc/sysrq-trigger

Using the echo b > /proc/sysrq-trigger simulates a keyboard key press which does invoke the Magic SysRQ kernel capabilities and hence instructs the kernel to immediately reboot the system.
However one should be careful with using the sysrq-trigger because it’s not a complete substitute for /sbin/reboot or /sbin/shutdown -r commands.
One major difference between the standard way to reboot via /sbin/reboot is that reboot kills all the running processes on the Linux machine and attempts to unmount all filesystems, before it proceeds to sending the kernel reboot instruction.

Using echo b > /proc/sysrq-trigger, however neither tries to umount mounted filesystems nor tries to kill all processes and sync the filesystem, so on a heavy loaded (SQL data critical) server, its use might create enormous problems and lead to severe data loss!

SO BEWARE be sure you know what you’re doing before you proceed using /proc/sysrq-trigger as a way to reboot ;).

Reboot Safely a frozen (hanged up) Linux Server with Magic SysRQ Key combination

Monday, June 20th, 2011

Linux Magic SysRQ Key picture

Being a remote system administrator for many years from now, I’ve experienced many times sudden Linux crashes, mostly caused by system hardware overloads.

This is a common thing especially on busy Web Servers with (Apache/MySQL). Situations like this are really messy and many times in order to bringt the server back online, one has to either physically go to the Data Center or contact the Technical support to request a server reboot.

In this terrible times, data loss might occur if the Server reset button is used to cold reboot it.

Happily in 99% of the cases the data loss which might occur could be prevented with Linux’s kernel capability to support the Magic SysRQ key !

Having the Magic SysRQ key functionality being supported in Linux in past times wasn’t that common, thanksfully these days this has changed andlmost every Linux distrubution supports this handy feature.

Now you might wonder what is the magic with those Magic SysRQ key ?

Let me explain, Magic SysRQ is a kernel level functionality which supports even completely crashed Linux systems with the horrifying:

Kernel Panic
message to be properly shutdown.

Using Magic SysRQ instead of the mostly used indiced cold reboots is really advantageous, as all the opened files by programs on the crashed server which hanged will be properly saved and closed and thus possible data loss caused by the sudden server crash will be minimized.

One other good thing about the Magic SysRQ Key keyboard combination is that initiating the Magic SysRQ could be made blindly (no need for server monitor or display to present any error messages on the failed server).

Now to check if the magic sysrq is enabled on a server one should issue the command:

Here are some Magic SysRQ keyboard combinations one can use in case of server failure:

ALT+SYSRQ+M to dump memory info;
ALT+SYSRQ+P to dump processes states;
ALT+SYSRQ+S to sync disks;
ALT+SYSRQ+U to unmount all mounted filesystems;
ALT+SYSRQ+E to terminate processes;
ALT+SYSRQ+I to kill all processes
ALT+SYSRQ+U to try to unmount once again;
ALT+SYSRQ+B to reboot.

I would skip to explain what each of the keyboard combinations will do as I believe the above description explains it well.

One classics of combinations one might want to issue on a failed Linux server supporting the Magic SysRQ would be:

ALT+SYSRQ+R
ALT+SYSRQ+E
ALT+SYSRQ+I
ALT+SYSRQ+S
ALT+SYSRQ+U
ALT+SYSRQ+B

The ALT+SYSRQ+REISUB key combination is very popular among system administrators.
Also Magic SysRQ is heavily used by kernel developers as it includes many handy debugging options.

If you try the Magic SysRQ key on older servers and you realize it doesn’t react you will have to recompile the linux kernel and enable the CONFIG_MAGIC_SYSRQ kernel time compilation option.

The Magic SysRQ can also be initiated remotely on a properly running server 😉 by initiating:

server:~# echo b > /proc/sysrq-trigger

This command would be useful if you want to just have fun and test that magic sysrq works on your system for sure 😉

To sum it up using the Magic SysRQ will guarantee your locked up, server a Safe Reboot and will hopefully save you a lot of time for backups recovery.