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I had read about the transparent compression that zfs offers. I wanted to verify it so I did, and sent my results off.

As we all know no experiment is valid unless verifiable. I wanted be sure that the transparent compression was actually working so I set up a sample zfs volume and purposefully made some files that i knew would compress really well. I grabbed their sizes, transferred them to another machine without zfs, and compared the size. It works.

1. Create the zfs filesystem
root@machine1:~# zfs create rpool/ztest
root@machine1:~# zfs set mountpoint=/ztest rpool/ztest

as soon as you do this /ztest shows up in the filesystem
root@machine1:~# ls /ztest/

2. enable compression and set it use gzip at level 6 (default)
root@machine1:/ztest# zfs set compression=gzip rpool/ztest

3. create some files you know will compress well
time for i in $(seq 1 3); do echo -n “file${i} “; echo $(seq 1 10000000) >> file${i} 2>&1; done

4. check the compression ratio
root@machine1:/ztest# zfs get compressratio rpool/ztest
NAME         PROPERTY       VALUE        SOURCE
rpool/ztest  compressratio  3.69x        -

5. verify the compression is working by transferring the file to a machine without such an awesome FS, and checking the filesize there
root@machine1:/ztest# du -sh file1
23M     file1
scp -rvp /ztest/file1 root@machine2:/root/file1

root@machine2]# du -sh file1
83M    file1

Conclusion: transparent compression is working, and working rather well on a file I made to be easily compressed.

I figured out how to remotely power cycle the two poweredge 850’s I have remotely. I used dells ipmitool rpms and a little help from the internet.
1. Install the rpms
2. load the needed modules
modprobe ipmi_si
modprobe ipmi_devintf
3. configure the network, and auth as seen here
4. test xxxx

Here. This includes the oggzrip utility. Maybe later I’ll give instructions for compiling things you intend to turn into packages. If I feel like it that is; biatches.

Splunk is google for logfiles. Even the free license is all I would ever need with syslog configured properly on each server.

It seems like a quick way to diagnose system performance problems. Link.

To measure bandwidth between two points. Link.

Using perl of coarse. It took me a second to get this to work; but its pretty easy:

perl  -pi.bak -e ’s/string1/string2/g’

I know I am very late to the Xen party. I try to stay on top of the life changing software, but there have just been so many new things out there over the past two years or so. I tried running a Xen kernel a while back under fedora core 6, but there were serious problems with xen and the ivtv kernel module driving my pvr500. I was using that for my mythtv backend, which the wife had gotten used to. Guess which had to go. FF >> 2007. I am priming my hardware for a complete replacement, and have already ebayed the tuner card. I figured what the heck; I have a free afternoon. Why not install a xen kernel, and experiment? Good times. Between xen and perl I blew the weekend. I started to write a screen scraper for surfthechannel.com but I got bored. Here is what I have so far….

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I know its been a while. I got an RHCE, got a new job, and moved to NYC. I want to build a GSM -> UMA tool. I can use wifiroamd.

I was using the included backup application that came with OS X, and their online .mac backup solution, but now that my .mac subscription is dead and done, I have decided to go with rsync.net for those few files that I absolutely cannot lose. For just under $6 US a month I get 3 GB of offsite storage that I can access via any of the ssh flavors (ssh/scp/sftp), rsync, or my personal favorite rsync over ssh. It was really easy. After I signed up I just put my public key up, then ran something like…
rsync -azvrpg –progress -e ssh backup username@myserver.rsync.net:/username/dir
This basically says sync the directory named backup on this machine with a directory of the same name inside of /username/dir on the machine myserver.rsync.net, and oh yeah use the lovely encryption that ssh affords us. I’ll probably make a cron to do this for me once a day/week tomorrow.