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Nokia N900 IPv6 Support

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1. Launch the X-Terminal application
2. Type in the command: “sudo gainroot”
3. Type in “apt-get install kernel-power-flasher” to launch the request to install the IPv6-enabled kernel available at Extras-Testing repository
4. Accept ll confirmations
5. After finishing the download, the new kernel will be flashed automatically to your N900 device. Now turn of the device and then turn on the device to reboot.

Now you are able to use ipv6 module

To add very simple ipv6 address install “IPROUTE” to use “ip” command.

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ip -6 a a 2001:470:1f0b:1514::100/64 dev wlan0

OSI Reference Model

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OSI is the Open System Interconnection reference model for communications. The OSI model is mainly used as a point of reference for discussing other protocol specifications such as TCP/IP and Net Ware.

The OSI reference model consists of seven layers that each defines a set of typical networking functions. The upper layers (application, presentation, and session; or Layers 7, 6, and 5) define functions focused on the application. The lower four layers (transport, network, data link, and physical; or Layers 4, 3, 2, and 1) define functions focused on end-to-end delivery of the data. Layer 2 is where switching is based, while Layer 3 is where routing is based.

Here are example protocols for eachlayer:

  • (7) Application – Telnet, HTTP, FTP, WWW browsers, NFS, SMTP gateways (Eudora, CC:mail, SNMP
  • (6) Presentation – JPEG, ASCII, EBCDIC, TIFF, GIF, PICT, encryption, MPEG, MIDI
  • (5) Session – RPC, SQL, NFS, NetBIOS , SSH, DECnet SCP
  • (4) Transport – TCP, UDP, SPX
  • (3) Network – IP, IPX, AppleTalk DDP
  • (2) Data Link – IEEE 802.3/802.2, HDLC, Frame Relay, PPP, FDDI, ATM, IEEE 802.5/802.2
  • (1) Physical – EIA/TIA-232, V.35, EIA/TIA-449, RJ-45, Ethernet, 802.3, 802.5, B8ZS

Python Comparison Operators

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All following comparison operators have the standard mathematical interpretation and return a boolean value of True for true, False for false:

Comparison operations are supported by all objects!

This table summarizes the comparison operations:

Operation Meaning
< strictly less than
<= less than or equal
> strictly greater than
>= greater than or equal
== equal
!= not equal*
is object identity
is not negated object identity

* != can also be written <>, but this is an obsolete usage kept for backwards compatibility only. New code should always use !=.

Setting up Soft RAID

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This is a very quick guide to setting up a Linux software RAID.

All these examples are same for RAID0 and RAID1

0. Disclaimer
Make sure you back up all your data, or you have empty hdds before you proceed.

1. Disk management
I’m using 2 same HDDs with 400Gigs.

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Disk /dev/sdb: 400.0 GB, 400088457216 bytes
Disk /dev/sdc: 400.0 GB, 400088457216 bytes

I created on both disks new partitions with parted (also you can use gparted):

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/dev/sdb1               1       48641   390708801   83  Linux
/dev/sdc1               1       48641   390708801   83  Linux


2. Raid creation

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$ aptitude update
$ aptitude install mdadm

For RAID-0

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$ mdadm --create /dev/md0 --level=0 --raid-devices=2 /dev/sdb1 /dev/sdc1

For RAID-1

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$ mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb1 /dev/sdc1

3. Get RAID information

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$ fdisk -l
Disk /dev/md0: 800.1 GB, 800171491328 bytes
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$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid0 sdc1[1] sdb1[0]
      781417472 blocks 64k chunks
 
unused devices: <none>
</none>
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$ mdadm --detail --scan
ARRAY /dev/md0 level=raid0 num-devices=2 metadata=00.90 UUID=fb3d1fd3:5dd2b871:01f9e43d:ac30fbff
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$ mdadm --detail /dev/md0 
/dev/md0:
        Version : 00.90
  Creation Time : Fri Aug 27 21:27:51 2010
     Raid Level : raid0
     Array Size : 781417472 (745.22 GiB 800.17 GB)
   Raid Devices : 2
  Total Devices : 2
Preferred Minor : 0
    Persistence : Superblock is persistent
 
    Update Time : Fri Aug 27 22:46:13 2010
          State : active
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0
 
     Chunk Size : 64K
 
           UUID : fb3d1fd3:5dd2b871:2ce552e4:6d63ea58
         Events : 0.3
 
    Number   Major   Minor   RaidDevice State
       0       8       17        0      active sync   /dev/sdb1
       1       8       33        1      active sync   /dev/sdc1

4. Create file system
That all you have a running RAID array, to use it you need to create a filesystem for example ext3 one.

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mkfs.ext3 /dev/md0

Delete RAID array:

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mdadm --stop /dev/md0

To make sure it doesn’t come back, you need to delete the RAID super blocks…

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mdadm --misc --zero-superblock /dev/sdb1
mdadm --misc --zero-superblock /dev/sdc1

You can mount your raid partition automatically on server start:

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vim /etc/fstab

And add this line to it:

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/dev/md0        /mnt           ext3    defaults    0   0

md0 will automatically mounted to /mnt/

Start a partially built array:

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$ mdadm --run /dev/md0
 
 
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] 
md0 : active raid1 sdb1[0] sdc1[1]
      390708736 blocks [2/2] [UU]
      [&gt;....................]  resync =  0.0% (277568/390708736) finish=70.3min speed=92522K/sec

Don’t forget the RAM usage:

Postgresql

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Some basic postgre commands:







\d [NAME]      describe table, index, sequence, or view
 \d{t|i|s|v|S} [PATTERN] (add "+" for more detail)
                list tables/indexes/sequences/views/system tables
 \da [PATTERN]  list aggregate functions
 \db [PATTERN]  list tablespaces (add "+" for more detail)
 \dc [PATTERN]  list conversions
 \dC            list casts
 \dd [PATTERN]  show comment for object
 \dD [PATTERN]  list domains
 \df [PATTERN]  list functions (add "+" for more detail)
 \dg [PATTERN]  list groups
 \dn [PATTERN]  list schemas (add "+" for more detail)
 \do [NAME]     list operators
 \dl            list large objects, same as \lo_list
 \dp [PATTERN]  list table, view, and sequence access privileges
 \dT [PATTERN]  list data types (add "+" for more detail)
 \du [PATTERN]  list users
 \l             list all databases (add "+" for more detail)