Thoughts on operating systems, software engineering and beyond
I really do not like this trend of animated GIFs (again!). The animations are overly intrusive and on pages like Google+ it has become a nightmare!
But there is a magic option in Firefox, and it is all detailed here: Configuring Firefox animated images option (animated_images)
I have set mine to “none“, no animations/annoying-distractions at all! Free again!
A quick comparison of average speeds for my daily commute, these numbers are average moving speed.
Note: Bulls is the brand name of my standard trekking bike, Raleigh is the brand name of my wife’s pedelec city/confort bike (electrical pedal-assist up to 25 km/h) and Peugeot is the brand name of our car.
Each of these modes of transport has 2 average speeds. For bicycles, one should understand the “easy” one as going slow enough to avoid too much sweating, whereas the “fast” one is when trying to be as fast as possible. For the car, it is the lowest and highest measured speed (depending on traffic).
For more information on pedelecs: Wikipedia article on Pedelec.
What service do I want to run on my Home Server?
I do have a NAS already which has the following services: File Sharing (Samba, AFS and NFS), Media Streaming Server (DLNA), VPN Server, Cloud Sync Repository. So I do not intend to have redundant services on my Home Server. What is left?
My Home Server could support:
*: FreeBSD support is uncertain.
As one can see, I could use Linux or BSD based OS or a mixture. However, ZFS is so compelling that I am seriously considering to go for FreeBSD+jails and basta cosi! February will be the month where I try to set-up a FreeBSD server.
I am experimenting with different OS to find the right settings for my Home Server. I was interested by Fedora especially because there are several “Red Hat” technology which I would like to use on my server, namely: oVirt and virt-manager. Furthermore it sports a recent Linux Kernel (3.7 as of this writing) which could be beneficial if I choose Btrfs for the underlying file system.
However, testing the upgrade path from Fedora 17 to Fedora 18, I am not so thrilled by the robustness of this OS. I have managed after painfully hitting 3 different blocking bugs to recover from the upgrade and have a nice Fedora 18 up and running. But this gave me little trust in the Q&A of the community. It seems that it is not the first time such problems happen (see Fedora 11).
I am still willing to give a go to Fedora. But out of precaution, I am going to experiment first with Ubuntu (for which I had since 2006 only once an upgrade problem). I want to see the state of oVirt and virt-manager on this OS before I am making any choice.
Or maybe I forget entirely about Linux based OS, and I go for FreeBSD with several jails instead of using virtualisation. Though I would need to check the state of technologies like ownCloud, (n)IDS, etc. on this OS.
I have finally my Home Server built, it has its first storage hard drive and I upgraded the memory to something decent. Time to install the operating system.
I am not yet fully decided which operating system to implement on my Home Server, I would love ZFS as a file system for managing my storage, but I would still want to use Linux and not make the full switch to BSD. I decided to go for Fedora as the main OS, and install BSD in a virtual machine and see how this setup performs.
I had tried for a few month Fedora 17 in a virtual machine, I liked it, although I prefer the Debian package manager over yum, but this is really based on my own feelings and not on technical grounds.
So let’s go and install Fedora 18 (just released) on my server.
The number of errors you find in forums or user groups is sometimes amazing. Here in this thread, the first answer mix up file system journaling with indexing, the second rightly tries to correct the thread but adds more errors by stating that ZFS is a journaling FS, which it isn’t. It is a transactional copy-on-write file system.
And this other thread on Ubuntu Forums is even worse. First, people do not exactly answer the question, some just express opinion/beliefs without facts, finally some are trying to base their answers on facts but those are incorrect. Example: “NTFS does not have a journal, neither is it 64 bit like Ext4.” (it is pretty hard to have that many wrong facts in one sentence, bravo!) Thanks, some users are trying to sanitize this thread (e.g. Udayakiran or falconindy), sadly their answers are flooded in the mass of bad/wrong ones.
In my previous post, I was stating that ZFS on Linux was not mature enough. The native ZFS port to Linux, although active, is still in release candidate stage and requires significant work to install. As for the ZFS FUSE version, it is still a 0.7 version not updated for long but it is easy to install on Ubuntu as it is available in the Software Centre (the link only works if your system supports the ‘apt:‘ scheme like on Ubuntu).
I have tried and installed the later, and although I cannot give any conclusion from a stability/reliability point of view, I was able to perform successfully the same steps I had performed on FreeBSD using ZFS.
Sadly ZFS on Linux is not at the same maturity level than on FreeBSD (or even Solaris). There is a FUSE implementation but it is now more than 16 month since anything happen there, and in my opinion not yet stable. Regarding native ZFS port, only one ZFS implementation for Linux is still developed by the Lawrence Livermore National Laboratory but it is still a release candidate version.
The state of ZFS on Linux is perhaps not too good today, but there is another file system in development and good support that could soon compete with ZFS, its name is btrfs (pronounce ‘butter-fs‘). Btrfs is still experimental
Yesterday, one of my virtual machines running Oracle Linux 6.3 got its root file system full, as it was configured with LVM it was not so much trouble but I wanted to try btrfs. I decided to move the /var to another partitions using btrfs. I have created a new hard disk in my VM and started it. Here is the rest of the story.
Warning: following these instructions might break your system. As an advice, create a virtual machine and experience with it before doing so on a real system.
Today I stumble upon an article regarding SSH on Oracle’s blogs.
One interesting feature I did not know is the SSH escape character ‘~’. So many times I had to open another terminal just to do one command locally before returning to the SSH session. Now this is over, just type ~^Z (a tilde followed by Ctrl-Z). Example
malmur :: ~ » uname -a FreeBSD malmur 9.0-RELEASE-p3 FreeBSD 9.0-RELEASE-p3 #0: [...] malmur :: ~ » ssh 192.168.78.10 unbreakable :: ~ » uname -a Linux unbreakable.linux 2.6.39-200.29.1.el6uek.x86_64 #1 [...] unbreakable :: ~ » ~^Z [suspend ssh] [1] + 2540 suspended ssh 192.168.78.10 malmur :: ~ » fg [1] + 2540 continued ssh 192.168.78.10 unbreakable :: ~ »
This article is a follow-up of an earlier post about ZFS on FreeBSD. We have created a ZFS pool with one disk and put some data on it. Now we want to mirror the data to safeguard them from disk failure.
In my virtual machine I created a new disk of the same size than previous ZFS dedicated disk and fire-up the machine.
But before I added the second disk, I decided to create a dataset (of the file system type) inside the pool I have created in previous article. The dataset will be configured to replicate internally the data for safety. This is an entirely optional step which I did just to experiment with ZFS.
The reader should notice that my pool had only 1 drive which means that each file in this dataset will appear twice on the same drive. If the drive fails, everything is lost. It just help if one version of the file gets corrupted, ZFS will detect it and use the (hopefully) uncorrupted copy to restore the file.
# zfs create -o copies=2 laug/safe
Dataset copies are in addition to any pool configuration such as mirroring or RAID-Z. In case of a stripped pool (the case if you use zpool add command), ZFS will try to use different disks in the pool for each copy, if it can! In case of mirrors (the case if you use zpool attach command) or RAID-Z, in addition to the pool duplication of data, ZFS will try to keep extra copies on different drives.
As the hard disk is exactly of the same size (same disk space and number of sectors) I can reuse the commands from the previous articles:
gpart create -s gpt ada2 gpart add -b 2048 -s 41932733 -t freebsd-zfs -l disk01 ada2
But now we are going to add the new disk to the existing pool in a mirror configuration. For this we use zpool attach:
# zpool attach laug ada1p1 ada2p1
# zpool status
pool: laug
state: ONLINE
scan: resilvered 1.37M in 0h0m with 0 errors on Tue Jul 31 18:16:43 2012
config:
NAME STATE READ WRITE CKSUM
laug ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
ada1p1 ONLINE 0 0 0
ada2p1 ONLINE 0 0 0
errors: No known data errors
As I don’t have much data on my pool, the resilvering was fast (see the scan message). In addition, one can see that the 2 disk partitions are now inside a mirror.
I really like ZFS, the command line interface is clean, it is easy to manage and it is powerful.