QWORQS

First thing first, using the manual, your commands will go in dry run mode, no hints are given on why needed changes are counted but not executed, this is because you have to rn the command with the y switch to do the changes, here are a few ones you will use often

dbmail-util -dy – set delete status on deleted mail (deleted by IMAP or POP)
dbmail-util -py – delete messages with delete status

dbmail-util -by – rebuild the caches

Without the Y, no changes will be made to the database

My always on Linux machine is a dell FX 160, very low power consumption, should work as my VPN, asterisk server, and wake up other computers when i need them, the device itself is multi homed, So i basically need it to wake up other devices on one of the networks

The commands you need for this to work are as follows

etherwake -i eth1 xx:xx:D2:B2:30:C9 (My laptop)

eth1 is the network connected to my mini linux server that is connected to the target network.

Thats all there is to it, in addition to enabeling wake on lan in your BIOS

SSDs are the best thing that happened to computer boot time (and many other things) since the invention of the abacus

But for some reason, booting up is faster than shutting down, much faster, Shut downs are taking a long time (Or reboots)

So let me see what i can do about this

1- Windows ClearPageFileAtShutdown is something that happens before shut down, and is my first guess to why this is happening
So let us set the following key to zero (0) and see if this speeds up shutdown time.

HKEY_LOCAL_MACHINE\CurrentControlSet\Control\SessionManager\Memory Management then ClearPageFileAtShutdown set to (0)

This session should shut down slowly, the next time you boot, shutdown will be much faster.

The other thing that i am thinking is relevant is changing the location of the indexing service index files to my spinning disk, this is because the spinning disk has thousands of files, and i would like to keep my SSD fast for certain other applications.

Although the copy program cp in Linux overwrites without prompting, in practice, it does not, the reason behind that is that the command is aliased with the (cp -i), you can check that by using the alias command

So there are 2 solutions to this to make cp overwrite

The first would be to unalias, while the second would be to execute the command directly with

\cp

Or you can use the full path to the alias command like

/usr/bin/cp

I personally use

\cp this that

This probably applies to both 840 evo and 850 evo, but not the EVO 840 PRO and the 850 evo pro because the pro are not TLC

All over the internet, people are saying that solid state drives don’t need to be aligned because they will scramble the used flash cells anyway for wear leveling.

This is absolutely NOT TRUE, although wear leveling does work that way (to put it in simple terms), the mapping algorithm that levels the writes maps blocks to other blocks.

So here is how it works, let us assume there was no wear leveling, when the partition is not properly aligned to a starting offset which is a multiple of the erase block size, writes and erase operations that should require the erasing of one block could end up erasing and writing to two blocks, now the block is a hardware restriction, so when the wear leveling algorithm selects a new location, the problem of erasing two cells instead of one is still valid.

Don’t take my word for it, mess up the alignment of one of your partitions, then examine reads and writes of 512 or 4K, both will be much slower.

Now, what you need to do is to align the file system to block size

Because this disk has a 1.5M erase block 1536 KiB and to be sure we want it to also align with 2048 KiB (Just in case the erase block is not the whole story), you can set the sector alignment value to 12288 (6144 KiB), which is a multiple of 1536 KiB and 2048 KiB.

So, in LINUX, even though it is usually correctly aligned by the partitioning software (And in windows it is already done for you and if not it can be done by samsung’s magician software), you can check the current alignment with.

fdisk -l /dev/sdb

For your own math, the EBS (Erase block size) on those drives is 1.5MBs

So basically, 12288 is 3*4k, the three comes from the fact that it is a three level cell (TLC)

The best computer-tv setup for your living room

Here, i am posting this to remind myself of how to setup my media center at home, so it can be a bit messy

Kodi (XBMC) seems to be the only real competitor to Windows Media center, in my case, i feel it is much better than Windows Media Center.

Hardware

The raspberry PI 2 (With 1 GB ram) can function as the hardware with it’s HDMI output

Or

An old PC, with cooling switched to passive watter cooling (Cost me around $40 on ebay for the parts) to get rid of the noisy fan, and with the hard drive replaced by a bootable linux flash stick (Also to reduce noise)

Please note that the analogue (D-SUB / VGA) cable is just as good as HDMI, analogue signal over such a short distance is not a problem, so you can connect the D-SUB to your TV or the HDMI cable, you will not notice the difference. But you will need to connect audio to external speakers or something.

The disadvantage of the old PC method are

The cooling system costs half as much as a raspberri PI ! alot of money i would say.
The PC is bulky compared to the PI
Draws much more power than the PI

The advantages

You already have that old PC
You can use Kodi on Windows, then use your IPAD as a keyboard and mouse (No such app exists for linux yet)
You can use it for more general purpose purposes later on
It’s eithernet port is not provided through USB like the PI
You can have much more RAM on it
You can add an input card to it and connect your home receiver to it
You can install hard drives inside (Remember to make them spin down when not in use) and then use it as NAS
You can install an IR receiver on the com port and use LIRC to program any remote you have
It can play DVDs (If it has a DVD player)

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Plugins that i like for Kodi

I have been using DD for a long time, specify the block size etc, then pipe it into PV if you like, and there you have it

But you can use PV directly

So let us assume we want to put sda on sdb (See how direction arrows are pointing out of sda in the command)

pv < /dev/sda > /dev/sdb

and you are done, no need for DD, PV is faster because it checks the speed on both disks first, and there you have it

At first it will be much faster than you anticipated, that is because it is buffering in RAM, once you run out of ram, the speed will drop back, even if you dont run out of ram, there will be time for the sync operation

For example, while cloning my 40GB SSD onto an 80GB western digital, at first the speed was 180MB/s, once i ran out of ram, it dropped to 50MB/s

There are 2 popular packages to deal with duplicate files on linux

The first would be fslint (apt-get install fslint), the down side is that it is not sorting by file size, because when i have 10,000 duplicate files on my disks, i really don’t want to deal with them all and make choices, so what comes to mind is this, the second is fdupes, i have never used it before so i would not know, so we will be using fslint with a small script.

first, find the duplicate files, in my case, i only want the ones over 2MBs

/usr/share/fslint/fslint/findup /hds -size +2048k > /root/dups.txt

Now, this little simple script should read the data into a mysql table (Command line PHP script, you will need to edit the mysql username, password and database), you also need to tell it what the path you used in the command above is (I used
“/hds”), also included is the database sql file, you can put that in with PHPMyAdmin

Now, you can run the above script and it will go and investigate file sizes on the file system.

Then, you can either walk through the database after sorting by size, or write your own display script (Fetch and print, nothing too fancy), so you will know where your greatest gains are, and this way you will not lose a day filtering those duplicate files.

Have fun, and please let me know what you think

This is a simple thing, there is nothing special about the PI, first, connect it to a wireless dongle (USB is your only option anyways), then create a file with your network settings, because of the scenario this is written for, and it is written as a reference for someone, I will connect it to an android hotspot, the subnet here is specific to android, others should use your own according to their router.

1- create the following file at /etc/wpa_supplicant/wpa_supplicant.conf

network={
ssid="isam"
psk="abcabc1234"
proto=RSN
key_mgmt=WPA-PSK
pairwise=CCMP
auth_alg=OPEN
}

Now, modify the file /etc/network/interfaces

For Signal quality and other relevant information, use the following command

iwconfig

Just because this took a lot of research from me (Looking at specs), I am posting this here for my own reference.

Note: CF cards will work on both 3.3V and 5V. so there is a bit of a mystery on why we need a voltage step down chip and a jumper for this particular adapter, other drives are clearly incompatible IDE interfaces.

it turns out that when combined with a converter using the fc1307a chip to create CF out of 2 SD cards, it will not work without a voltage step down, with the wrong setting, or with cards with no step down, a computer will see the combined cards, but will fail when trying to format them for some reason.

The 1.8″ adapter (Sideways IDE interface) is 3.3V, the normal 2.5″ disks are 5 Volt, the adapter we have that turns CF cards into 1.8″ or 2.5″ compatible drive, has a JUMPER to select, this jumper effectivly activates or deactivates the voltage step down chip (The only chip on the board)

So there you have it, 1.8″ and 2.5″ PATA drives are not compatible regardless of the fact that the PIN interfaces are the same. the adapters with a voltage step down will work on both, but you need to set them up first with a JUMPER