stratosgear.com

Reading List: Ringworld

2011-11-01T19:59:00.001+02:00

No wonder this has won both Hugo and Nebula awards in 1970/71.

I was not very fond of Niven's writing style (this is the first Larry Niven book I read) and maybe he used it for this book only. The plot though was ingenious. The idea of the Ringworld was very interesting. It kept me entertained from the beginning until the end.

Highly recommended! :) Read more about the plot on wikipedia.

Reading List: Time Enough for Love

2011-10-14T11:33:00.000+03:00

Lazarus Long
1916-4272
The capstone and crowning achievement of Heinlein's famous Future History, TIME ENOUGH FOR LOVE follows Lazarus Long through a vast and magnificent timescape of centuries and worlds. Heinlein's longest and most ambitious work, it is the story of a man so in love with Life that he refused to stop living it; and so in love with Time that he became his own ancestor

(From the books back cover)

I think Heimlein is one of my favorite authors. "Time enough for Love" was nominated for the Nebula Award for Best Novel (1973) and the Hugo and Locus Awards (1974) and although did not finally win, nonetheless it is quite an interesting read.

As always, I cannot outdo the Wikipedia article on the book.

Change the timezone in Ubuntu server

2011-10-06T14:33:00.002+03:00

Couldn't be easier:

sudo dpkg-reconfigure tzdata

Then follow the text wizard.

First International Space Station overhead pass

2011-09-03T22:11:00.001+03:00

Today I saw my first overhead pass of the ISS.

For some time I was registered to Twisst and I was receiving their notifications on Twitter but I never actually bothered to really look up and see the station fly overhead. Well, in my defense, living in Athens, with all this light pollution you can barely see the sky and the stars, so I was waiting for the right opportunity before I actually tried.

So, today at 20:52 (right as Twisst predicted) I saw the ISS. The brightness was supposed to be at a magnitude of -1.6 (I have no idea how bright that is) and I was wondering what was I was supposed to be looking at. Suddenly, approximately where I was looking at, a very bright star appeared out of nowhere. And I could see it with a naked eye.

It was brighter than the other current stars I could see at the moment and it moved at a pretty high speed accross the sky. It looked like an airplane was flying overhead, but at a quite fast pace. The whole pass took approximately 5 minutes and the station traversed an arc almost two thirds of the sky. Then, slowly, in 5-6 seconds, while it was still moving, faded out to nothing.

I must have look like an idiot, standing there in the middle of the park (it was Azul's nightly walk) gazing at the sky for five minutes. But, I think it was worth it...

Translating an online PDF document with Google Translate

2011-06-14T15:38:00.000+03:00

Hey,

If you pass the link of the online PDF document to the Google Translate service then Google will extract the text from the PDF and translate it in the language that you selected. It doesn't keep the exact same page formatting but the PDF is now very readable. Much more readable than it was before... :)

I didn't know that!

stratos?ear.com word play

2011-06-04T02:04:00.005+03:00

It's funny how many of the following domain names are actually working (and how many of the letter combinations actually make sense):

www.stratosaear.com

www.stratosbear.com

www.stratoscear.com

www.stratosdear.com

www.stratoseear.com

www.stratosfear.com works!

www.stratosgear.com obviously!

www.stratoshear.com works!

www.stratosiear.com

www.stratosjear.com

www.stratoskear.com

www.stratoslear.com works!

www.stratosmear.com

www.stratosnear.com
www.stratosoear.com

www.stratospear.com

www.stratosqear.com

www.stratosrear.com

www.stratossear.com

www.stratostear.com

www.stratosuear.com

www.stratosvear.com

www.stratoswear.com works!

www.stratosxear.com

www.stratosyear.com

www.stratoszear.com

Απατεωνιές στην τιμολόγηση internet της Cosmote

2011-05-28T22:27:00.001+03:00

Ξαφνικά άρχισαν να μου έρχονται κάποια SMS στο καρτοκινητό μου ότι:

ΜΟΛΙΣ ΣΥΝΔΕΘΗΚΕΣ ΣΤΟ INTERNET ΜΕ ΧΡΕΩΣΗ 1Ε ΓΙΑ 24 ΩΡΕΣ. ΜΠΟΡΕΙΣ ΝΑ ΣΕΡΦΑΡΕΙΣ ΑΠΕΡΙΟΡΙΣΤΑ ΑΠΟ ΤΟ ΚΙΝΗΤΟ ΣΟΥ ΜΕΧΡΙ ΤΙΣ 22/05/11 11:45 ΧΩΡΙΣ ΕΠΙΠΛΕΟΝ ΧΡΕΩΣΗ.

Στην αρχή νόμιζα ότι έκανα εγώ κάποιο λάθος, αλλά σήμερα διασταύρωσα με την αδερφή μου ότι γίνεται και σε εκείνην το ίδιο. Σε αυτήν είχαν ήδη χρεώσει περίπου 20 ευρώ και όταν πήρε τηλέφωνο την εξυπηρέτηση πελατών της είπαν ότι είναι μια καινούρια υπηρεσία της Cosmote και αν δεν την θέλει μπορεί να την απενεργοποιήσει.

Συγνώμη!!! Με ρώτησε κανείς εμένα αν θέλω αυτήν την "καινούρια υπηρεσία" πριν αρχίσουν να μου την χρεώνουν; Έστειλα εγώ κανένα SMS ενεργοποίησης πουθενά;

Ποιός ξέρει πόσα παράνομα τέτοια ευρώ έχει μαζέψει η Cosmote με αυτήν την απάτη.

Έλεος...

[Update 1η Ιουνίου 2011]:

Μετά από λίγο googling βρήκα τα εξής:

Αυτή η υπηρεσία λέγεται Cosmote Internet Day Pass.
Σύμφωνα με τα λεγόμενα τους:

"Η υπηρεσία COSMOTE Internet Day Pass είναι προενεργοποιημένη σε όλους τους συνδρομητές Συμβολαίου, ΚαρτοΣυμβολαίου και Καρτοκινητής που δεν έχουν ενεργοποιημένο κάποιο πρόγραμμα ή πρόσθετη υπηρεσία που να παρέχει πρόσβαση στο Internet."

Και πάλι, επιμένω, κανείς δεν με ρώτησε αν θέλω την αυτόματη ενεργοποίηση.
Τέλος, για να απαλαγείς από τις χρεώσεις (κάτι που θα έπρεπε να αναφέρεται και στα SMS που στέλνουν) απλά στείλε δωρεάν SMS με τις λέξεις END DAY στο 1333.

[Update 30 Σεπτεμβρίου 2011]:

Το μύνημα ξαναεπέστρεψε (μαζί με την χρέωση). Τώρα, και καλά, το έχουν "φτιάξει λίγο" γιατί μερικά δευτερόλεπτα μετά το πρώτο μύνημα (με το ΜΟΛΙΣ ΣΥΝΔΕΘΗΚΕΣ ΣΤΟ INTERNET κτλ κτλ) σου στέλνουν κι' άλλο μύνημα που λέει:

ΑΝ ΕΧΕΙΣ SMARTPHONE ΣΥΣΚΕΥΗ Η ΠΡΟΣΒΑΣΗ ΣΤΟ INTERNET ΙΣΩΣ ΟΦΕΙΛΕΤΑΙ ΣΕ ΕΦΑΡΜΟΓΕΣ (ΚΑΙΡΟΣ-ΝΕΑ-Ε-MAIL) ΠΟΥ ΣΥΝΔΕΟΝΤΑΙ ΑΥΤΟΜΑΤΑ. ΓΙΑ ΠΛΗΡΟΦΟΡΙΕΣ ΚΑΛΕΣΕ ΤΟ 13838

Βασικά, δηλαδή, φταίει η συσκευή σου που είναι smartphone και έχει την απαίτηση να συνδεθεί στο internet. Δεν φταίμε εμείς, η Cosmote, που ξεδιάντροπα αποφασίσαμε για σένα ότι θέλεις να χρεώνεσαι κάθε μέρα ένα ευρώ χωρίς να έχεις ερωτηθεί πρώτα! Όχι, μάλλον φταίνε οι εφαρμογές του τηλεφώνου σου.

Επίσης στο μύνημα που σου στέλνουμε ΔΕΝ σου λέμε πως να το απενεργοποιήσεις, αλλά πάρε μας τηλέφωνο να σε χρεώσουμε και γι'αυτό. Άσε που μερικοί μπορεί και να μην το κάνουνε, οπότε θα συνεχίσουμε να τους χρεώνουμε τα ευρώ.

Πήρα πάλι τηλέφωνο για να δώ πως τελικά απενεργοποιήται αυτό το πράγμα. Για να σας γλυτώσω και τα άλλα 0.135€ που σε χρεώνουν στο 13838 (οι ρεζίληδες) οι οδηγίες είναι οι εξής:

(όπως είχα αναφέρει και πριν) Στέλνεις END DAY στο 1333.

Απαντάνε με:

ΤΟ ΑΙΤΗΜΑ ΣΑΣ ΕΙΝΑΙ ΥΠΟ ΕΠΕΞΕΡΓΑΣΙΑ

και μετά από λίγο:

ΤΟ ΑΙΤΗΜΑ ΣΑΣ ΓΙΑ ΑΠΕΝΕΡΓΟΠΟΙΗΣΗ ΤΗΣ ΥΠΗΡΕΣΙΑΣ COSMOTE INTERNET DAY PASS ΟΛΟΚΛΗΡΩΘΗΚΕ.

Javascript PC Emulator - Technical Notes

2011-05-21T19:17:00.000+03:00

It's amazing what you can do if you put your mind to it.

Just visit: http://bellard.org/jslinux/

Quoting from his technical notes:

Javascript PC Emulator - Technical Notes: "What's the use ?

I did it for fun, just because newer Javascript Engines are fast enough to do complicated things. Real use could be: Benchmarking of Javascript engines (how much time takes your Javascript engine to boot Linux ?). For this particular application, efficient handling of 32 bit signed and unsigned integers and of typed arrays is important.
Learning to use command line Unix tools without leaving the browser.
Client side processing using an x86 library, for example for cryptographic purposes. For such application, the x86 emulator can be modified to provide an API to load x86 dynamic libraries and to provide a js-ctypes like API to call the C/C++ functions from javascript.
A more advanced version would allow to use old DOS PC software such as games."

Adding Syntax hilighting to Blogger posts

2011-05-11T21:28:00.000+03:00

Add the following code right before the close of the </head> tag.

[Update]
Scrap the above. I switched to Google's code prettify.

Recording streaming audio workflow

2011-04-25T12:38:00.004+03:00

My choice of Ubuntu tools for recording, splitting and tagging streaming audio.

Recording
streamripper: Command line tool. Excellent choice since it makes it so easy to schedule recordings with it.

$ streamripper URL -d /home/stratos/outRec -l 7800 -d /dir/to/save -t --xs-none

-l 7800: The duration of the recording (in seconds)
-d /dir/to/save: Directory where to save the stream.
-t: Do not overwrite files in recording folder.
--xs-none: Do not try to find silent parts in the recording

Of course adding to cron is quite easy:

$ crontab -e

0 6 * * 1 streamripper URL -options

for recording every Monday morning at 6.

Splitting
audacious: Audio player that has a nice Left-Right cursor key playback to easily find the places in the stream recording that you want to split/cut. Mark the Start and End Time from the recording that you made.

mp3splt: Using the Start and End Times from above, use them to split the recording. Don't bother with the `mp3splt-gtk` gui app.

$ mp3splt recording.mp3 65.36 124.33 -a -o finalRecording

65.36: The start time from the original recording that the split will start
124.33: The end time from the original recording that the split will end.
-a: This option will slightly adjust the start and end time to fall on a silent period.
-o finalRecording: The final splitted file.

Tagging
easyTag: Use it to put mp3 tags in the final recording. Actually, any tagger would do. This is a, well, easy one!

Happy recordings!

Configure Ubuntu server to send email through Gmail

2011-04-06T08:46:00.003+03:00

Edit the `/etc/postfix/main.cf` file and set the follow values:

smtpd_tls_key_file =
smtp_use_tls = yes
relayhost = [smtp.gmail.com]:587
transport_maps = hash:/etc/postfix/transport
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous

Create/edit the `/etc/postfix/transport` file with:

gmail.com smtp:[smtp.gmail.com]:587

Create/edit the `/etc/postfix/sasl_passwd` file with:

[smtp.gmail.com]:587 username@gmail.com:password

Obviously, change the `username` and `password` values.

Note: If you use Google's 2-step verification you should not use your traditional password, but rather visit the https://www.google.com/accounts/b/0/IssuedAuthSubTokens page and generate a new password for postfix.

Finally, issue:

Profit.

Create and mount xfs filesystem

2011-03-28T11:24:00.003+03:00

Couldn't be easier:

$ sudo apt-get install xfsprogs
$ sudo mkfs.xfs /dev/sdf

Add to fstab:

/dev/sdf   /my/location   xfs  defaults,nobootwait,noatime    0    0

This was tested on Amazon EC2 with EBS volumes.

Installing MySQL module in Django virtualenv

2011-03-20T14:42:00.002+02:00

In order to correctly install mysql bindings in a Django virtualenv you need:

First install some Ubuntu dependencies:

Then create the virtual env and install the python packages:

I was missing the `libmysqlclient-dev` package and I was getting a `EnvironmentError: mysql_config not found` when running the `pip install mysql-python`.

Change codepage on windows console

2011-02-21T11:28:00.002+02:00

If find this essential when administrating ORACLE databases from the command line and the locale of the database is set to Greek. I prefer to read the output in Greek rather in gibberish:

chcp 1253

Dune

2011-01-06T12:18:00.000+02:00

I was looking to print a nice PnP (Print and Play) game and I came across Dune.

The game is nicely redone, from it's original 1979 publishing, so thick with theme from the book, that really made me wanna read the book again. First time I read it was while a was a freshman in university (back in '89).

And in case you didn't know, this book is often quoted as THE best science fiction novel with more than 12 million copies sold worldwide.

The wikipedia article is very informative, too.

Convert an A4 sized .pdf file to A5 size

2011-01-05T00:27:00.006+02:00

I was working on a LyX document based on the Tufte layout and unfortunately the page layout was available at A4 page sizes only (ok, US letter, too, but that doesn't count :)

I could try and learn Latex and create my own page size but the task looked monumental. I am sure the solution might be easy enough, but I just couldn't do it myself. Googling for A5 sized tufte layouts didn't help either.

So to the command line it is.

From LyX export you final document to postscript format, let's say myBook.ps.

Then:

This will convert the original .ps to another sized at A5. Unfortunately it will need further tweaking.

Open the myBook.A5.ps postscript file and delete the `%%DocumentMedia` line (if one exists).

Also change the existing `%%BoundingBox:` line to:

%%BoundingBox: 0 0 421 595
%%DocumentPaperSizes: a5
%%BeginPaperSize: a5

Note: On a couple of documents I could not locate the `%%BoundingBox:` line and the structure of the .ps file was a little weird. As a workaround try to edit the:

%%BeginPaperSize: a5
/setpagedevice where
{ pop << /PageSize [420 595] >> setpagedevice }
{ /a5 where { pop a5 } if }
ifelse
%%EndPaperSize

section. In it's original format it will contain A4 references and the dimensions would be [595 842].

Finally create your PDF file:

Open myBook.pdf and marvel at your handiwork... :)

Forever War

2010-11-04T12:23:00.000+02:00

Private William Mandella is a reluctant hero in an interstellar war against an unknowable and unconquerable alien enemy. But his greatest test will be when he returns home. Relativity means that for every few months' tour of duty centuries have passed on Earth, isolating the combatants ever more from the world for whose future they are fighting.

(From the book's back cover)

Wow, this was a very nice read. I never thought of that particular aspect of time dilation, when travelling at the speed of light. Talking about a meaningless war that drags it's feet...!

Two thumbs up for "The Forever War", On to "Forever Peace" now...

Installing Virtualbox on Ubuntu Server 10.04

2010-10-22T10:50:00.005+03:00

Wanna install Virtualbox on a headless Ubuntu server?

First do a:

Then download the appropriate .deb for your architecture from http://www.virtualbox.org/wiki/Linux_Downloads

Finally, install with:

(Ok, I installed virtualbox 3.2 on a 64 bit server, yours might vary)

Extra credit
If you want to make your life REAAALY easy you should also install phpvirtualbox on the host Ubuntu server and get a shiny web based GUI administration screen that looks almost exactly like the native GUI Virtualbox application.

The Left Hand of Darkness

2010-10-20T22:32:00.000+03:00

Winter is an Earth-like planet with two major differences: conditions are semi artic even at the warmest time of the year, and the inhabitants are all of the same sex. Tucked away in a remote corner of the universe, they have no knowledge of space travel or of life beyond their own world. And when a strange envoy from space brings news of a vast coalition of planets which they are invited to join, he is met with fear, mistrust and disbelief.

(From the book's back cover)

I barely had enough patience to finish this book. I wonder how come it got both the Nebula and the Hugo awards.

What was so special about the a single man trying to convince a newly discovered planet to join the Ekoumen (from the Greek word "οικουμένη")?. It could have been vastly more interesting, but the pace and the subject matter of the character conversations were a complete turn off for me. I couldn't wait for the book to finish. Good thing it was a short one.

If you want a nice Ursulla Le Guin book, you're better off with the "Earthsea Trilogy"

Summary

2010-10-20T11:21:00.002+03:00

So to sum it all up:

Create sandbox

Create RAID5 array

Create LVM2 volumes

Format / Mount the volume

Extend an LVM2 Logical Volume

Remove an LVM2 Logical Volume

Replace a failed RAID disk

Add new disks to RAID5 array

Increase size of RAID disks

Recover lost RAID array

And that's how it's done.

RAID Manipulation

2010-10-20T11:18:00.004+03:00

Playing with LVM2 is nice because you can manipulate and assign the available space you have any way you want. The actual unseen hero is the RAID5 volume that we have created because it provides a guarantee that even if one disk fails we will not lose our data. Let's play with the RAID disks now.
Fail a RAID disk and recover

Hopefully you will never have to face a failed disk, but it is quite important to know what to do if a disk fails. For now, in our comfortable sandbox we will imitate a failed disk and we will check if we'll lose any data.

Notice that the state is clean, degraded meaning that the files are OK but the state of the array is, well, degraded.

Do we still have our files?

Yep, still here. Now, let's remove the failed disk (as if you are opening the computer case and removing the failed disk)

Ok the disk is removed. Now let's assume that you replace the failed hard drive, that you have recreated a similar partition as the one originally used and you are ready to fix the degraded RAID array.

Now, immediately after adding the disk the array will start reconstructing itself. It should look something like:

Notice how the state is clean, degraded, recovering and that the Rebuild Status process is at 32% percent. Depending on the size of your array the process might take from some minutes (I doubt it) up to some hours or days. You can always check the process with the above command. The array should be still usable and accesible even while it is getting reconstructed, but I really wouldn't like to push my luck, so I wouldn't suggest doing any work in the array until the reconstruction is done.

In our case the reconstruction, for a tiny 120MB array, takes merely seconds and if we check the state again we see:

Nice and clean. Let's hope you never have to go through a procedure like this, EVER.

Increase the RAID array size

Up until now we were playing with LVM2 volumes and the allocated space that was assigned to the LVM2 Physical Volume. But, what should we do if we want to create a Logical Volume larger than the 49 PE that the Volume Group contains? Well, not much unless we increase the number of PE.

This can be done in two ways:

Increase the number of disks in the RAID5 array or
Increase the size of the disks already in the array.

Add new disks to the RAID array

Adding a new disk in the array is easy (assuming you still have free SATA ports in your motherboard).

Let's run an example:

So we added the newly created disk to the array and mdadm considers the new disk a "spare" disk. A spare disk is considered a disk that is in standby mode ready to substitute a failed disk (automatically, I think; needs investigation). The spare disks capacity does not participate in the total capacity of the array, as it is in standby mode. Let's make it a part of the array:

Immediately after the new disk is added to the array, mdadm starts reconstructing the array. Here we see a 19% complete status and the upgrade notification of 3->4 disks. Again, depending on your disks sizes this might take some time, and probably longer than adding a failed disk to the original disk array size because all the data will have to be re-written and spread across the new disk.

The array should still be functional and up and running during the whole procedure. Once it's done we have to allocate the extra space to the LVM2 Physical Volume and resize the lvm-group LVM2 Volume Group.

First let's see how much space the Physical Volume has:

So, although we have added a fourth disk in the RAID array the LVM2 Physical Volume is still at 200MB.

Let's increase it:

As you see the Physical Volume now is 300MB. A nice side-effect is that the lvm-group Volume Group was also automatically resized, because when we initially created we used all the available space of the Physical Volume, so it kept using all the available PE. So now we have a total of 74 PE to play with. If you want to increase the size of your Logical Volumes you can now easily do it (see the 'Resize Volumes' above).

But do we still have our data?

Yep, still here.

Increase the size of the RAID disks

In reality (as in my personal case) you will end up increasing the initial RAID size because you want to substitute the original disks with larger ones. The prices keep dropping and the amount of SATA ports in a motherboard are finite. So, sooner or later you will need to replace the disks, with larger ones.

Unfortunately, you cannot do the upgrade at your leisure. That is, you just can't drop a 1TB disk together with a couple of 640GB disks and expect to create a RAID5 array larger than the original (3-1) x 640GB = 1280GB RAID5 array. You will have to upgrade all the disks at the same time, if you want to expand your RAID5 array. You can always, upgrade just one disk, though, and use the extra space of the larger disk as another partition.

So, for now, we have a 4 disk array with 100MB capacity each. Let's substitute each disk with a 150MB one (one at a time).

What we did was to fail, remove and substitute one disk with another, bigger one. As always the procedure is not instantaneous and the "adding" of the larger disk into the array should take some time.

When the array has finished restructuring, from the last add we did, lather-rinse-repeat for the remaining disks (loop2, loop3 and loop4 in our case). When you are done with all disks:

The array is still 300MB (4 - 1) * 100MB = 300 MB! What happens is that during the introduction of the larger disks into the already existing array, mdadm is using a partition as large as the existing partitions that already are part of the array. So basically although we are adding a 150MB disk, the array is using only 100MB, just as the already existing older 100MB disks.

When we substitute all four disks, we can resize the array and use the remaining 50MB from each disk. Let's do it:

Finally done. The array is now 450MB (4-1) * 150MB = 450 MB. But how about the Volume Groups we had?

As you see we went from 74 PE to 112 PE. Now we can go back to normal LVM2 volume manipulation to take advantage of the gained space.

Recover RAID array

OK, but what happens when something happens and you lose your RAID array?

Let's just say that you whole motherboard just fails and you have to take your disks and set the machine again. Or, when you re-install the OS and you want to remount your RAID array.

The actual neccessary file, to identify and mount the RAID array lives in /etc/mdadm/mdadm.conf and it looks like this:

Note the ARRAY definitions that tell mdadm what arrays you are currently using.

On a newly created system this file will be probably missing and you will have to recreate it.

If you already have an /etc/mdadm/mdadm.conf file in your system, but you are missing the ARRAY definitions you can force mdadm to create these definitions for you:

All you have to do is append these lines at the end of the /etc/mdadm/mdadm.conf file.

If you don't have an mdadm.conf file at all you can quickly produce one:

Now, if you reboot you should have you array back. Well, done!

LVM2 Setup

2010-10-20T11:14:00.002+03:00

At this point we could format the /dev/md3 partition with some filesystem and start using it. But that's the old way of doing it. What we want to do is run LVM2 on top of the RAID5 partition so we can better utilize the space provided by the /dev/md3 partition, allowing us to dynamically create, resize and remove volumes in the space provided.

Create the LVM2 partitions
In order to use LVM2 we first have to create a LVM2 Physical Volume:

So, we see here that the three 100MB loopback files have been combined to a 200MB RAID5 LVM2 Physical Volume (3 disks - 1 parity = 2 disks * 100 MB = 200MB usable space)

Next we will create a LVM2 Volume Group:

From the vgdisplay command we should note the Free PE size value. PE stands for Physical Extends and it the minimum amount of storage unit that we can use to create our final LVM2 volumes. Basically we have 49 PE to allocate as we wish for LVM2 volumes. Each PE is 196MB / 49 = 4MB of size.

Let's create a LVM2 Logical Volume with 20 PE (20 * 4MBs = 80MB):

Finally, the LVM2 volume has been created. Let's see what's left from the lvm-group Volume Group:

OK. The allocated PE are 20 and we have another 29 unallocated.

Create the mountable volume
The newly created LVM2 volume is unformatted:

Now let's mount it:

So, now we finally have a 80MB volume that is sitting atop a RAID5 partition.

Let's put some files in the this volume so we can test if the tests we will run later on will make us lose our data.

As long as the **test.txt** file is there through all our following tests, then our data is safe.

LVM2 Manipulation
Let's play with the 49 available PE given to us from the lvm-group Volume Group.

Add more volumes

Create another LVM2 Logical volume:

Now we have another volume with 10 PE (40MB).

Resize volumes

We have myVolume with 20 PE and myVolume2 with 10 PE. We should have 19 PE still unallocated.

Let's increase the size of myVolume by 10 PE:

Do we still have our files?

So far so good.

Remove volumes

We have another volume, myVolume2 that we created for fun for 10 PE (40 MB). Let's remove it and reclaim the space:

So, now we have 19 free PE. The allocated 30 are from myVolume (20 initial + 10 after the resize)

Initial Setup of RAID Array

2010-10-20T11:10:00.001+03:00

Now we have three partitions /dev/loop1, /dev/loop2 and /dev/loop3 that will imitate some actual /dev/sdXX, /dev/sdXX and /dev/sdXX partitions.

Now, let's combined them to create our RAID5 array:

Creating the RAID sandbox

2010-10-20T11:05:00.001+03:00

The sandbox will consist of some loopback files that will simulate disk partitions. We will use these "fake" partitions to create our array. That way there will be no harm on your actual disks.

Let's imitate the creation of the RAID5 partition. First we will create three loopback files of 100MB each:

With the loopback files created we can mount them as partitions:

The Demon Princes

2010-10-05T23:37:00.000+03:00

Kirth Gersen carries in his pocket a slip of paper with a list of five names written on it. Theses are the names of the five Demon Princes who led the historic Mount Pleasant Massacre, which destroyed not only Kirth's family but his entrire world as well. He roams the universe, searching the endless galaxies of space, hunting down the Demon Princes and exacting his revenge. Three princes will fall before Kirth's work is done, and two more await their doom...

(from the book's back cover)

This is Volume One that includes the first three books of the series: The Star King, The Killing Machine and The Palace of Love.

The Star King

Gesrhen is against Attel Malagate. Attel is not human, but rather a type of species, later called Star Kings, that can quickly mutate (through not so many generations) and approximate the best qualities of similar species that surrounds them. When humans colonized their planet, Star Kings quickly became a species that rivaled even human themselves.

An interesting concept in the book (apart from the detective work that Gershen has to go through to locate Attel) is Smade's Planet and Smade's Tavern. Smade, apparently fed up with society, took his family and set up a tavern, appropriately named Smade's Tavern, on a remote uninhabited planet. The only inhabitants of the planet is Smade and his family running the tavern. The planet is locate Beyond (beyond the limits of what is considered explored civilized galaxy) and the tavern is patroned with fugitives and outlaws looking to relax a little.

Smade runs a quite civil establishment and although his clientele is of doubtful morality, they must obey his rules or face his wrath.

The Killing Machine

The Killing Machine contains THE BEST villain name I have ever read: Kokkor Hekkus. It sounds so mean, that I do not even have to read a description of the vile things Mr.Hekkus has performed in his life. The fact that he is a "hormagaunt", extending his life by stealing children and kind of "distilling" them (it doesn't even sound nice), in order to extend his lifespan, doesn't make him any more likable, either.

The concept of the "Interchange" is the interesting fact of this book. Basically the Interchange, located in a secure planet, acts as an intermediary between kidnappers and ransomers. They safely keep the kidnapped victims and accept payments from their family that they forward to the kidnappers. Their motto is that everything is civilized and they offer the assurance and the much needed good faith that the whole procedure will be as smooth as possible with no surprises from either party. They take a cut of the ransom and try to be as civilized and humane to the kidnap victims. Since they guarantee such efficiency, it is to the best interest of everyone involved that they continue providing their services as is.

The Palace of Love

Gershen is after Viole Falush on this one.

With all due respect to Mr.Vance, this book hurt my head. Having to read through so much rumble from the mad poet Navarth (oh, he was quite mad, alright) was making me skip a page every so often just to get to the conclusion of it all. I had no interest at all on either Viole Falush, the plot as it was unfolding, or their dialogs, that were disjointed and led to no plausible or understandable conclusions.

My guess is, that even if you skip this book, in the Demon Princes pentalogy, you wont miss much.