Setting up a scan server with Fedora 17 - network scanning with a HP Photosmart C4485 All In One (HP C4400 Series)

I've had my HP Photosmart C4485 All-in-one Printer/Scanner/Copier attached to my Fedora 17 linux server for ages. It's been shared on the network with CUPS, meaning any device in the household can print to it. I recently needed to scan an image for the first time since setting up the server so had to find out a bit about using SANE (linux's scanner service) over the network.

I found some very useful instructions here which I mostly followed: http://www.x2b4.com/2008/06/15/howto-share-you-scanner-on-a-network-with-fedora-9/

I was having problems with scanimage -L not showing the printer/scanner, even though sane-find-scanner was showing it was connected. After a while I realised I didn't have the SANE HPAIO backend. This was fixed with

# yum install libsane-hpaio

I didn't bother creating the script suggested in the link which automatically changes the permissions on the scanner.

I had tried getting saned to run as its own user, but this wasn't working, so I set up the config file under /etc/xinetd.d/ to run saned as root - not ideal for security but it's unlikely that anyone I don't know about will be on the network.

There was a head-scratching moment when I couldn't find the scanner from a client machine (ie the computer I wanted to scan from) until I realised I had to edit the client's /etc/sane.d/net.conf to allow the SANE net backend to connect to the scanner host (ie my server with the scanner attached).

Here's an outline of the steps I took, in a sensible order:
1. Make sure SANE works locally on the server by checking the output from  sane-find-scanner and scanimage -L. (this is after I installed the libsane-hpaio package

2. Configure SANE to share the scanner on the network by adding these lines to the access list in /etc/sane.d/saned.conf :

localhost
192.168.1.0/24

(you'll need to change the second line to suit your network's IP address range)

3. Add firewall rules as in the link above, to allow access from the network

4. Create a file in /etc/xinet.d/ to get xinetd to invoke the SANE service when needed (as in the link)

5. On all clients (computers you want to use the scanner from), add the server IP address or hostname to /etc/sane.d/net.conf

Thank you, x2b4!

Fitting a Ford Focus Estate with ISOFIX child seat attachment

I recently bought a second-hand Ford Focus Estate 1.8 TDCi Ghia, 2007. I assumed it would have ISOFIX as standard, as all the information I'd found online, and the owners' manual, suggested this. It turns out however that it's an optional free extra, and my particular car didn't have it fitted. After some googling around I found this thread on on focusowners.com: Ford Focus ISOFIX installation So it's simple.

Amazon actually stock this part (Ford part number 1357238) with (currently) free delivery:

Ford 1357238 Britax ISOfix Mounting Kit for Childseats 2004 Onwards for Focus
Delivery was very quick.

Installation took about 20 minutes. I needed a T45 driver bit and a flat head screwdriver. Following the instructions from the focusowners.com thread, I used the screwdriver to push the seat-back hinge (nearest the door) over and lifted the seat-back up from the hinge. With a bit of wiggling the seat-back could be completely removed from the centre attachment. Under the seat-back in the metal floor were two bolt holes plugged with grey rubber bungs which were easily removed.

I bolted the fitting with the square brackets (the actual ISOFIX attachments) oriented to the bottom edge (the Ford logo stamped on the bar was upside-down). The seat went back into place (a firm bang down gets the hinge back in place) and the fitting was ready to be used. Easy! I don't know why this isn't done as standard, but at least it's not a great deal of hassle to sort.

Photos to come, when I remember.

Auto-rip CDs on headless server using udev and abcde

I have a lot of CDs, at least 500. Some of them have over the last few years made their way in FLAC form to the hard disk of my main PC, but now this collection is on the server, I'd like to add the rest of the CDs to the digital library and finally store them out of the way. I wanted a way for the server to do the work of ripping the CDs without any user intervention apart from putting a CD in the drive and taking it out again.

Linux's udev system provides a way for programs to be triggered on hardware events, such as a CD being inserted. In Fedora, udev rules files can be added to /etc/udev/rules.d/ and they will be magically picked up and used.

I wrote a rules file that looked like this:
/etc/udev/rules.d/99-autoripcd.rules

SUBSYSTEM=="block", KERNEL=="sr0", ENV{ID_CDROM_MEDIA_CD}=="1", RUN+="/usr/bin/cdautoinsert" 

Simply, this looks in sysfs's /sys/block/sr0/ for a CD (instead of a DVD) to be inserted, and runs the commmand given by RUN+. This is a shell script which runs the useful cd ripper, abcde. Here is the script:
/usr/bin/cdautoinsert

#/bin/bash

PATH=/usr/lib64/ccache:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin /bin/abcde -NVP | tee /var/log/abcde-auto.log &

exit

The key to getting this working (and which took some googling to work out) is to pass a PATH to whatever commands you run in the script. This is because udev runs commands (as root) without much of an environment, and abcde was failing to find cdparanoia and the other tools it relies on. The other useful thing to know is to make sure commands are run with & to make the shell detach those processes, otherwise udev will hang until the job is complete, which is about 5 minutes for a typical cd.

I edited /etc/abcde.conf to give abcde defaults that work for me, including:
INTERACTIVE=n     (the -N switch on abcde's command line also does this)
ACTIONS=cddb,read,encode,tag,move,clean
OUTPUTTYPE=flac
OUTPUTFORMAT='${ARTISTFILE}/${ALBUMFILE}/${ARTISTFILE}-${ALBUMFILE}-${TRACKNUM}.${TRACKFILE}' (this fits with the directory structure of my music collection)
EJECTCD=y


When writing your own udev rules, the udevadm tool is handy.
udevadm monitor will show udev events as they happen (so you can see which subsystem to look at)
udevadm info --name=/dev/sr0 --query=all will list everything udev knows about the CD drive

ZFS on Linux - replacing a failed drive in a RAIDZ pool

My server was built using 4 250gb hdds which were passed on to me by a friend who didn't need them any more. One of them failed - no problem, I thought, I have a spare and ZFS will take care of resilvering etc.

Power down the server, swap out the drive, reboot.

# zpool replace tank <failed drive id> <replacement drive id>

gave a Device not in pool error.

Googling suggested exporting then reimporting the pool, but all

# zpool export -r tank

got me was "Pool busy", even though there were no processes accessing it according to fuser and lsof, and zpool iostat showed 0 reads or writes.

Eventually I hit upon this issue in the ZFSonlinux bug tracker:https://github.com/zfsonlinux/zfs/issues/976

Finally a solution to my original problem. I needed full paths to the device names.

# zpool replace tank /dev/disk/by-id/<failed drive id> /dev/disk/by-id/<replacement drive id> 

did the trick:

# zpool status
  pool: tank
 state: DEGRADED
status: One or more devices is currently being resilvered.  The pool will
 continue to function, possibly in a degraded state.
action: Wait for the resilver to complete.
 scan: resilver in progress since Fri Sep 28 00:02:04 2012
    12.3G scanned out of 205G at 24.5M/s, 2h14m to go
    3.07G resilvered, 5.98% done
config:

 NAME                                           STATE     READ WRITE CKSUM
 tank                                           DEGRADED     0     0     0
   raidz1-0                                     DEGRADED     0     0     0
     ata-VB0250EAVER_Z2ATRS75                   ONLINE       0     0     0
     ata-WDC_WD2500AAJS-22RYA0_WD-WCAR00411237  ONLINE       0     0     0
     ata-WDC_WD2500JS-75NCB3_WD-WCANK8544801    ONLINE       0     0     0
     replacing-3                                UNAVAIL      0     0     0
       ata-WDC_WD2500JS-75NCB3_WD-WCANKC570943  UNAVAIL      0     0     0
       ata-SAMSUNG_SP2504C_S09QJ1SP156094       ONLINE       0     0     0  (resilvering)

errors: No known data errors

Success! Still don't know what was causing the "pool busy" error when trying to export.

I expect this should work in ZFS on Linux for all zpool operations that refer to individual vdevs or disks, like zpool add, zpool remove, etc.

Automatically share on boot ZFS filesystems via NFS in Fedora Linux using systemd

My media server project had a minor stumble when I found that after rebooting my server the ZFS shares were not showing on NFS clients, even though nfs-server.service was active.

I realised that the zfs shares were not being exported to NFS - I had assumed that ZFS on linux did this automatically on boot.

I wrote a simple systemd unit file to get this working on startup. This is what the file looks like:

/etc/systemd/system/zfs-share.service

[Unit]
Description=Start ZFS share-nfs sharing

[Service]
Type=oneshot
ExecStartPre=/bin/sleep 30
ExecStart=/usr/sbin/zfs share -a
ExecStop=/usr/sbin/zfs unshare -a
RemainAfterExit=yes

[Install]
WantedBy=default.target
After=nfs-server.service, zfs.service
Requires=nfs-server.service, zfs.service
 

This oneshot service simply runs the command

zfs share -a

after the NFS server and its dependencies have started.

systemctl stop zfs-share.service

should unshare the ZFS exports. In a another post I'll jot down how I got native ZFS working under Fedora 17, but it really was a case of following the simple instructions at http://zfsonlinux.org/

Edited 29/9/2012: Added 30-second sleep as ExecStartPre line to give time for ZFS to mount filesystems properly as I was getting errors due to a race condition.