Category Archives: Tips & Tricks

Gaining space on Android after ART->Dalvik switch (root access required)

I (still) use a Nexus S phone. I am using Cyanogenmod on it. After an article in a computer magazine I decided to give the ART-runtime a try instead of the default Dalvic-runtime. Unfortunately I do not have enough free space free (and all what I can is moved to the USB storage already) to really use the ART-runtime.

After switching back to the Dalvic-runtime, I had only 2/3 of the previously available space free. After a little bit of looking around I found /data/dalvik-cache. I deleted with a file manager the content of the directory (you will get some “app crashed/died” messages) and rebooted the phone (this is not the same as formatting the cache partition in the recovery system).

During boot it populated the directory again and now I have more than 4/3 of free space on the internal storage.


Updating FreeBSD 8.2 (or 9.x) to 10 (beta4)

This is a little description how I remotely (no console, booted into multi-user during update, no external services like jails/httpd/… running) updated a FreeBSD 8.2 to 10 (beta4) from source. This should also work when updating from FreeBSD 9.x. Note, I had already switched to ATA_CAM on 8.2, so not instructions for the name change of the ata devices. No IPv6, WLAN or CARP is in use here, so changes which are needed in this area are not covered. Read UPDATING carefully, there are a lot of changes between major releases.

What I did:

  • update /usr/src
  • make buildworld
  • replace “make ” in /usr/src/Makefile.inc1 with ${MAKE} (two times, one for “VERSION”, one for “BRANCH”)
  • verify kernel config for changes needed (running “config MyKernel” in /usr/src/sys/YourArch/conf/ helps to identify syntax problems), sorry I didn’t take notes, but I diffed the old and the new GENERIC config and added/removed according to my interests
  • /usr/obj/…/src/usr.bin/bmake/make buildkernel KERNCONF=MyKernel
  • /usr/obj/…/src/usr.bin/bmake/make installkernel KERNCONF=MyKernel KODIR=/boot/kernel.10
  • mergemaster –p
  • /usr/obj/…/src/usr.bin/bmake/make installworld DESTDIR=/somewhere/test
  • mkdir /root/net10; cp /somewhere/test/rescue/ifconfig /somewhere/test/rescue/route /root/net10
  • create the file /etc/rc.10update with:
    case $(uname –r) in
    export MYIFCONFIG
    export MYROUTE
  • change the files (stupid approach: grep for “ifconfig” and “route” in /etc/rc.d to identify files which need to change, I skipped files which I identified as not needed in my case, if you use pf/IPv6/bridge/…, you may have to change some more files) /etc/rc.d/auto_linklocal /etc/rc.d/defaultroute /etc/rc.d/netif /etc/rc.d/netwait /etc/rc.d/routing: add “. /etc/rc.10update” at the end of the block with “. /etc/rc.subr”, change the “ifconfig”-command to ${MYIFCONFIG}, change the “route”-command to ${MYROUTE}
  • change /etc/network.subr: add “. /etc/rc.10update” before the first function, change the “ifconfig”-command to ${MYIFCONFIG}, change the “route”-command to ${MYROUTE}
  • make sure that the changes you made are 100% correct, rather triple-check than to not check at all (you will be locked out if they are not 100% OK)
  • stop any jails and make sure they do not restart at boot
  • deactivate the gmirror of the root-fs, if there is one (it is maybe easier to ask a remote hand to swap the boot order in case of problems)
  • here you could just a reboot of the server to come back to your current OS version, so make sure that the modifications in /etc did not cause any problems with the old version (in case you see problems with the v10 kernel), but if you do not have a remote console to single-user mode you have no chance to directly fix the problem (risk mitigation described above), no matter which version of the kernel you boot
  • nextboot –k kernel.10
  • shutdown –r now
  • login
  • check dmesg
  • optional: mv /boot/kernel /boot/kernel.8
  • make installkernel KERNCONF=MyKernel
    to have a v10 /boot/kernel
  • make installworld
  • mergemaster
  • make delete-old
  • rm –r /etc/rc.10update /root/net10
  • change rc.conf: add “inet” in ifconfig-aliases
  • review sysctl.conf for outdated entries
  • shutdown –r now
  • optional: rm –r /boot/kernel.10
  • enable jails again (or later… updating jails is not described here)
  • activate/resync mirror(s)
  • rebuild all ports (attention: new pkg system)
  • make delete-old-libs
  • reboot again to make sure everything is OK after the port-rebuild and removal of old libs (a console.log (syslog.conf) helps here


Calculating the target size of H264 videos

From time to time I convert videos to H264. When I do this I want to get the best quality out of a give filesize. This means I create VBR videos. The question here is, how big the target video file shall be.

After searching around a little bit in the net I found a formula which is supposed to give a hint about the target filesize. Naturally this depends on the encoder (or even the encoder-version), the encoder settings and even the video.

The formula is at least a good hint for my use, so I wrote a script which calculates several filesize values for a given video (based upon the output of mediainfo, which the scripts expects in a file with the filename as an argument to the script). It calculates a CBR and a VBR value for a given video based upon the width, height and duration. It should work on all system with a POSIX compatible shell.

Example output for a video from my HD-ready cam, original filesize 1.8 GB:

Width: 1280, Height: 720, FPS: 50.000, Time: 1424, Motion: 2
Per second: 6451200.000 bps / 6300 Kibps
Total CBR: 1148313600 bytes / 1121400 KiB / 1095 MiB
Total VBR: 861235200 bytes / 841050 KiB / 821 MiB
Width: 1280, Height: 720, FPS: 50.000, Time: 1424, Motion: 3
Per second: 9676800.000 bps / 9450 Kibps
Total CBR: 1722470400 bytes / 1682100 KiB / 1642 MiB
Total VBR: 1291852800 bytes / 1261575 KiB / 1232 MiB
Width: 1280, Height: 720, FPS: 50.000, Time: 1424, Motion: 4
Per second: 12902400.000 bps / 12600 Kibps
Total CBR: 2296627200 bytes / 2242800 KiB / 2190 MiB
Total VBR: 1722470400 bytes / 1682100 KiB / 1642 MiB

There are 3 sections, the difference is the “motion” value. It is a kind of multiplicator depending on the amount of motion in the video. For the videos I made myself (family videos, and even some videos of volley ball games), the first section seems to be just fine. So I reduced the original MP4 file to about 50% (not visible here is the audio size, normally I copy the original audio unmodified).

For the curious ones, the formula is

width_in_pixels * height_in_pixels * fps * motion_value * 0.07

for the bps value. The CBR value is

bps * playtime_in_seconds / 8

and the VBR value is

3 / 4 * CBR_value.


Algorithm to detect repo-copies in CVS

FreeBSD is on its way to move from CVS to SVN  for the version control system for the Ports Collection. The decision was made to keep the complete history, so the complete CVS repository has to be converted to SVN.

As CVS has no way to record a copy or move of files inside the repository, we copied the CVS files inside the repository in case we wanted to copy or move a file (the so called “repocopy”). While this allows to see the full history of a file, the drawback is that you do not really know when a file was copied/moved if you are not strict at recording this info after doing a copy. Guess what, we where not.

Now with the move to SVN which has a build-in way for copies/moves, it would be nice if we could record this info. In an internal discussion someone told its not possible to detect a repocopy reliably.

Well, I thought otherwise and an hour later my mail went out how to detect one. The longest time was needed to write how to do it, not to come up with a solution. I do not know if someone picked up this algorithm and implemented something for the cvs2svn converter, but I decided to publish the algorithm here if someone needs a similar functionality somewhere else. Note, the following is tailored to the structure of the Ports Collection. This allows to speed up some things (no need to do all steps on all files). If you want to use this in a generic repository where the structure is not as regular as in our Ports Collection, you have to run this algorithm on all files.

It also detects commits where multiple files where committed at once in one commit (sweeping commits).


  • check only category/name/Makefile
  • generate a hash of each commitlog+committer
  • if you are memory-limited use ha/sh/ed/dirs/cvs-rev and store pathname in the list cvs-rev (pathname = “category-name”) as storage
  • store the hash also in pathname/cvs-rev

If you have only one item in ha/sh/ed/dirs/cvs-rev in the end, there was no repocopy and no sweeping commit, you can delete this ha/sh/ed/dirs/cvs-rev.

If you have more than … let’s say … 10 (subject to tuning) pathnames in ha/sh/ed/dirs/cvs-rev you found a sweeping commit and you can delete the ha/sh/ed/dirs/cvs-rev.

The meat

The remaining ha/sh/ed/dirs/cvs-rev are probably repocopies. Take one ha/sh/ed/dirs/cvs-rev and for each pathname (there may be more than 2 pathnames) in there have a look at pathname/. Take the first cvs-rev of each and check if they have the same hash. Continue with the next rev-number for each until you found a cvs-rev which does not contain the same hash. If the number of cvs-revs since the beginning is >= … let’s say … 3 (subject to tuning), you have a candidate for a repocopy. If it is >=  … 10 (subject to tuning), you have a very good indicator for a repocopy. You have to proceed until you have only one pathname left.

You may detect multiple repocopies like A->B->C->D or A->B + A->D + A->C here.

Write out the repocopy candidate to a list and delete the ha/sh/ed/dirs/cvs-rev for each cvs-rev in a detected sequence.

This finds repocopy candidates for category/name/Makefile. To detect the correct repocopy-date (there are maybe cases where another file was changed after the Makefile but before the repocopy), you now have to look at all the files for a given repocopy-pair and check if there is a matching commit after the Makefile-commit-date. If you want to be 100% sure, you compare the complete commit-history of all files for a given repocopy-pair.


Free DLNA server which works good with my Sony BRAVIA TV

In several previous posts I wrote about my quest for the right source format to stream video to my Sony BRAVIA TV (build in 2009). The last week-end I finally found something which satisfies me.

What I found was serviio, a free UPnP-AV (DLNA) server. It is written in java and runs on Windows, Linux and FreeBSD (it is not listed on the website, but we have an not-so-up-to-date version in the ports tree). If necessary it transcodes the input to an appropriate format for the DLNA renderer (in my case the TV).

I tested it with my slow Netbook, so that I was able to see with which input format it will just remux the input container to a MPEG transport stream, and which input format would be really re-encoded to a format the TV understands.

The bottom line of the tests is, that I just need to use a supported container (like MKV or MP4 or AVI) with H.264-encoded video (e.g. encoded by x264) and AC3 audio.

The TV is able to chose between several audio streams, but I have not tested if serviio is able to serve files with multiple audio streams (my wife has a different mother language than me, so it is interesting for us to have multiple audio streams for a movie), and I do not know if DLNA supports something like this.

Now I just have to replace minidlna (which only works good with my TV for MP3s and Pictures) with serviio on my FreeBSD file server and we can forget about the disk-juggling.


Tuning guide in the wiki

In the light of the recent benchmark discussion, a volunteer imported the tuning man-page into the wiki. Some comments at some places for possible improvements are already made. Please go over there, have a look, and participate please (testing/verification/discussion/improvements/…).

As always, feel free to register with FirstnameLastname and tell a FreeBSD committer to add you to the contributors group for write access (you also get the benefit to be able to register for an email notification for specific pages).


HOWTO add linux-infrastructure ports for a new linux_base port

In my last blog-post I described how to create a new linux_base port. This blog-post is about the other Linux–ports which make up the Linux–infrastructure in the FreeBSD Ports Collection for a given Linux-release.

What are linux-infrastructure ports?

A linux_base port contains as much as possible and at the same time as little as possible to make up a useful Linux-compatibility-experience in FreeBSD. I know, this is not a descriptive explanation. And it is not on purpose. There are no fixed rules what has to be inside or what not. It “matured

HOWTO create a new linux_base port

FreeBSD is in need of a new linux_base port. It is on my TODO list since a long time, but I do not get the time to create one. I still do not have the time to work on a new one, but when you read this, I managed to get the time to create a HOWTO which describes what needs to be done to create a new linux_base port.

I will not describe how to create a new linux_base port from scratch, I will just describe how you can copy the last one and update it to something newer based upon the existing infrastructure for RPM packages.

Specific questions which come up during porting a new Linux release should be asked on [email protected],  there are more people which can answer questions than here in my blog. I will add useful information to this HOWTO if necessary.

In the easy case most of the work is searching the right RPMs and their dependencies to use, and to create the plist.

Why do we need a new linux_base port?

The current linux_base port is based upon Fedora 10, which is end of life since December 2009. Even Fedora 13 is already end of life. Fedora 16 is supposed to be released this year. From a support point of view, Fedora 15 or maybe even Fedora 16 would be a good target for the next linux_base port. Other alternatives would be to use an extended lifetime release of another RPM based distribution, like for example CentOS 6 (which seems to be based upon Fedora 12 with backports from Fedora 13 and 14). Using a Linux release which is told to be supported for at least 10 years, sounds nice from a FreeBSD point of view (only minor changes to the linux ports in such a case, instead of creating a complete new linux_base each N+2 releases like with Fedora), but it also means additional work if you want to create the first linux_base port for it.

The mysteries you have to conquer if you want to create a new linux_base port

What we do not know is, if Fedora 15/16, CentOS 6, or any other Linux release will work in a supported FreeBSD release. There are two ways to find this out.

The first one is to take an existing Linux system, chroot into it (either via NFS or after making a copy into a directory of a FreeBSD system), and to run a lot of programs (acroread, skype, shells, scripts, …). The LTP testsuite is not that much useful here, as it will test mostly kernel features, but we do not know which kernel features are mandatory for a given userland of a Linux release.

The second way of testing if a given Linux release works on FreeBSD is to actually create a new linux_base port for it and test it without chrooting.

The first way is faster, if you are only interested in testing if something works. The second way provides an easy to setup testbed for FreeBSD kernel developers to fix the Linuxulator so that it works with the new linux_base port. Both ways have their merits, but it is up to the person doing the work to decide which way to go.

The meat: HOWTO create a new linux_base port

First off, you need a system (or a jail) without any linux_base port installed. After that you can create a new linux_base port (= lbN), by just making a copy of the latest one (= lbO). In lbN you need to add lbO as a CONFLICT, and in all other existing linux_base ports, you need to add lbN as a conflict.

Change the PORTNAME, PORTVERSION, reset the PORTREVISION in lbN, and set LINUX_DIST_VER  to the new Linux-release version in the lbN Makefile (this is used in PORTSDIR/Mk/ and PORTSDIR/Mk/

If you do not stay with Fedora, there is some more work to do before you can have a look at chosing RPMs for installation. You need to have a look at PORTSDIR/Mk/ and add some cases for the new LINUX_DIST you want to use. Do not forget to set LINUX_DIST in the lbN Makefile to the name of the distribution you use. You also need to augment the LINUX_DIST_VER check in PORTSDIR/Mk/ with some LINUX_DIST conditionals. If you are lucky, the directory structure for downloads is similar to the Fedora structure, and there is not a lot to do here.

When this is done, you can have a look at the BIN_DISTFILES variable in the lbN Makefile. Try to find similar RPMs for the new Linux release you want to port. Some may not be available, and it may also be the case that different ones are needed instead. I suggest to first work with the ones which are available (make makesum, test install and create plist). After that you need to find out what the replacement RPMs for non-existing ones are. You are on your own here. Search around the net, and/or have a look at the dependencies in the RPMs of lbO to determine if something was added as a dependency of something else or not (if not, forget about it ATM). When you managed to find replacement RPMs, you can now have a look at the dependencies of the RPMs in lbN. Do not add blindly all dependencies, not all are needed in FreeBSD (the linux_base ports are not supposed to create an environment which you can chroot into, they are supposed to augment the FreeBSD system to be able to run Linux programs in ports like they where FreeBSD native programs). What you need in the linux_base ports are libraries, config and data files which do not exist in FreeBSD or have a different syntax than in FreeBSD (those config or data files which are just in a different place, can be symlinked), and basic shell commands (which commands are needed or not… well… good question, in the past we made decisions what to include based upon problem reports from users). Now for the things which are not available and where not added as a dependency. Those are things which are either used during install, or where useful to have in the past. Find out by what it was replaced and have a look if this replacement can easily be used instead. If it can be used, add it. If not, well… bad luck, we (the FreeBSD community) will see how to handle this somehow.

If you think that you have all you need in BIN_DISTFILES, please update SRC_DISTFILES accordingly and generate the distfile via  make –DPACKAGE_BUILDING makesum to have the checksums of the sources (for legal reasons we need them on our mirrors).

The next step is to have a look at REMOVE_DIRS, REMOVE_FILES and ADD_DIRS if something needs to be modified. Most of them are there to fall back to the corresponding FreeBSD directories/files, or because they are not needed at all (REMOVE_*). Do not remove directories from ADD_DIRS, they are created here to fix some edge conditions (I do not remember exactly why we had to add them, and I do not take the time ATM to search in the CVS history).

If you are lucky, this is all (make sure the plist is correct). If you are not lucky and you need to make some modifications to files, have a look at the do-build target in the Makefile, this is the place where some changes are done to create a nice user experience.

If you arrive here while creating a new linux_base port, lean back and feel a bit proud. You managed to create a new linux_base port. It is not very well tested at this moment, and it is far from everything which needs to be done to have the complete Linux infrastructure for a given Linux release, but the most important part is done. Please notify [email protected] and call for testers.

What is missing?

The full Linuxulator infrastructure for the FreeBSD Ports Collection has some more ports around a linux_base port. Most of the infrastructure for this is handled in Mk/

UPDATE: I got some time to write how to update the Linux-infrastructure ports.


How I setup a Jail-Host

Everyone has his own way of setting up a machine to serve as a host of multiple jails. Here is my way, YMMV.

Initial FreeBSD install

I use several harddisks in a Software–RAID setup. It does not matter much if you set them up with one big partition or with several partitions, feel free to follow your preferences here. My way of partitioning the harddisks is described in a previous post. That post only shows the commands to split the harddisks into two partitions and use ZFS for the rootfs. The commands to initialize the ZFS data partition are not described, but you should be able to figure it out yourself (and you can decide on your own what kind of RAID level you want to use). For this FS I set atime, exec and setuid to off in the ZFS options.

On the ZFS data partition I create a new dataset for the system. For this dataset I set atime, exec and setuid to off in the ZFS options. Inside this dataset I create datasets for /home, /usr/compat, /usr/local, /usr/obj, /usr/ports/, /usr/src, /usr/sup and /var/ports. There are two ways of doing this. One way is to set the ZFS mountpoint. The way I prefer is to set relative symlinks to it, e.g. “cd /usr; ln –s ../data/system/usr_obj obj

Another root-on-zfs HOWTO (optimized for 4k-sector drives)

After 9 years with my current home-server (one jail for each service like MySQL, Squid, IMAP, Webmail, …) I decided that it is time to get something more recent (specially as I want to install some more jails but can not add more memory to this i386 system).

With my old system I had an UFS2-root on a 3-way-gmirror, swap on a 2-way-gmirror and my data in a 3-partition raidz (all in different slices of the same 3 harddisks, the 3rd slice which would correspond to the swap was used as a crashdump area).

For the new system I wanted to go all-ZFS, but I like to have my boot area separated from my data area (two pools instead of one big pool). As the machine has 12 GB RAM I also do not configure swap areas (at least by default, if I really need some swap I can add some later, see below). The system has five 1 TB harddisks and a 60 GB SSD. The harddisks do not have 4k-sectors, but I expect that there will be more and more 4k-sector drives in the future. As I prefer to plan ahead I installed the ZFS pools in a way that they are “4k-ready

Converting from Courier IMAP to dovecot is easy

I have used Courier IMAP at home since a long time. As I want to update a dovecot 1.2 setup to dovecot 2.x, I decided to first have a look at dovecot 2.x at home.

Switching from Courier IMAP to dovecot is really easy. I just configured the correct path to the maildir, setup a passdb/userdb, and it was working.

The important part was the correct transfer of the passwords. I used already an userdb in Courier IMAP with MD5 passwords. For each user it has imappw=XXX with XXX similar to $1$abc.

This can be converted into a dovecot passdb/userdb line very easily:


The corresponding passdb/userdb settings for dovecot are:

passdb {
   args = scheme=MD5-CRYPT username_format=%u /usr/local/etc/dovecot/dovecot.pws
   driver = passwd-file
userdb {
   args = username_format=%u /usr/local/etc/dovecot/dovecot.pws
   driver = passwd-file

Compared to when I had a look the last time, dovecot is also able to use OTP as an authentication mechanism now. Unfortunately I did not find any documentation how to configure/use it.


HOWTO: creating your own updated linux RPM for the FreeBSD linuxulator

Background info

The FreeBSD linux compatibility environment currently uses RPMs from Fedora 10. Unfortunately Fedora 10 is end of life since a while. For one of the RPMs (the pango one) we where aware of a security vulnerability. As we do not know if it is feasible to update the linuxulator ports to something more recent, I decided to setup a VM with Fedora 10 and generate a new RPM for the linux-f10-pango port. Thanks to Luchesar V. ILIEV for explaining me how to do this.

Setup of the VM

I used VirtualBox 4.0.4 on a Solaris 10 x86 machine. I configured a fixed size disk of 16 GB and kept the default network setup (after installing the guest tools / kernel modules I switched to virtio, as I was not able to do anything useful besides a ping) and RAM size. The CD/DVD drive was configured to use the image of the full Fedora 10 DVD for i386 systems.

Setup of Fedora 10

Booting the VM from the DVD leads to the graphical Fedora 10 install software (after chosing to install a new system on the console). There I accepted all the defaults, except for the software to install. I deselected the Office and Productivity group and selected the Software Development group. When I was asked if I want to install some additional RPMs I had a look at the complete list and installed some I thought are necessary. I do not remember anymore which ones I chose, but everything which looks related to RPM building is a good candidate.

After a while the install will be finished and you can boot into the new system (eject the DVD from the drive before reboot). After reboot chose to install the Guest Additions in the menu of the VM. This should mount the ISO image in the VM. As root execute the file for Linux. This will build some kernel modules for better integration (e.g. seamless integration of the mouse between your desktop and the VM). At this point I rebooted and configured virtio as the NIC. I also had to configure the network settings by hand, as the GUI tool did not safe all the settings correctly.

Update and install of required RPMs

After the VM was up and the network configured, I updated the entire system (chose System Update in the menu). To update the pango port, I had to install the libthai-devel RPM. I had the RPM for it (and all the files I need to build a new pango RPM) already downloaded, so I did a “yum install /path/to/rpm

Cheap process monitoring (no additional software required)

I have an old system (only the hardware, it runs –current) which reboots itself from time to time (mostly during the daily periodic(8) run, but also during a lot of compiling (portupgrade)). There is no obvious reason (no panic) why it is doing this. It could be that there is some hardware defect, or something else. It is not important enough to get a high enough priority that I try hard to analyze the problem with this machine. The annoying part is, that sometimes after a restart apache does not start. So if this happens, the solution is to login and start the webserver. If the webserver would start each time, nearly nobody would detect the reboot (root gets an EMail on each reboot via an @reboot crontab entry).

My pragmatic solution (for services started via a good rc.d script which has a working status command) is a crontab entry which checks periodically if it is running and which restarts the service if not. As an example for apache and an interval of 10 minutes:

*/10 * * * *    /usr/local/etc/rc.d/apache22 status >/dev/null 2>&1 || /usr/local/etc/rc.d/apache22 restart

For the use case of this service/machine, this is enough. In case of a problem with the service, a mail with the restart output would arrive each time it runs, else only after a reboot for which the service did not restart.

Making ZFS faster…

Currently I play a little bit around with my ZFS setup. I want to make it faster, but I do not want to spend a lot of money.

The disks are connected to an ICH 5 controller, so an obvious improvement would be to either buy a controller for the PCI slot which is able to do NCQ with the SATA disks (a siis(4) based one is not cheap), or to buy a new system which comes with a chipset which knows how to do NCQ (this would mean new RAM, new CPU, new MB and maybe even a new PSU). A new controller is a little bit expensive for the old system which I want to tune. A new system would be nice, and reading about the specs of new systems lets me want to get a Core i5 system. The problem is that I think the current offers of mainboards for this are far from good. The system should be a little bit future proof, as I would like to use it for about 5 years or more (the current system is somewhere between 5–6 years old). This means it should have SATA-3 and USB 3, but when I look at what is offered currently it looks like there are only beta-versions of hardware with SATA-3 and USB 3 support available on the marked (according to tests there is a lot of variance of the max speed the controllers are able to achieve, bugs in the BIOS, or the  controllers are attached to a slow bus which prevents to use the full bandwidth). So it will not be a new system soon.

As I had a 1GB USB-stick around, I decided to attach it to the one of the EHCI USB ports and use it as a cache device for ZFS. If someone wants to try this too, be careful with the USB ports. My mainboard has only 2 USB ports connected to an EHCI, the rest are UHCI ones. This means that only 2 USB ports are fast (sort of… 40 MBit/s), the rest is only usable for slow things like a mouse, keyboard or a serial line.

Be warned, this will not give you a lot of bandwidth (if you have a fast USB stick, the 40MBit/s of the EHCI are the limit which prevent a big streaming bandwidth), but the latency of the cache device is great when doing small random IO. When I do a gstat and have a look how long a read operation takes for each involved device, I see something between 3 msec and 20 msec for the harddisks (depending if they are reading something at the current head position, or if the harddisk needs to seek around a lot). For the cache device (the USB stick) I see something between around 1 mssec and 5 msec. That is 1/3th to 1/4th of the latency of the harddisks.

With a “zfs send


In this post I write how to install FreeBSD on a remote linux system by creating a root image prepared for mirroring on a local system. There is no (free) access to the remote console, only access via ssh.

Background story

While I was at the university, I worked remotely for an ISP (administration of several FreeBSD systems). During this time I started to use my own domain, and I was allowed to host it directly at the ISP for free. I tried to not use too much space on the harddisk (at the end about 400 MB) and to not provide something which attracted too much people to keep the bandwith on a sane level. After the university I was still available to answer questions, and I was still allowed to host my website there for free. As the number of questions can be counted with IIRC one hand since then, I decided at some point (recently, to be exact

Easy library dependencies detection for ports

In the last days I committed some scripts to $PORTSDIR/Tools/scripts which help in detecting the explicit library dependencies of installed ports. You just have to run $PORTSDIR/Tools/scripts/ with the package-name of the installed port (alternatively you can give the path to the registered port, e.g. /var/db/pkg/gnome-terminal-2.18.1). One of the scripts which are called needs portupgrade installed. As an example here