Existe uma maneira de testá-lo respondido em unix. stackexchange.com por frostschutz (esta resposta é o seu mérito, portanto, obrigado), copiada abaixo:
"Crie um arquivo de teste: (não aleatório de propósito)
# yes | dd iflag=fullblock bs=1M count=1 of=trim.test
Obtenha o endereço: (o comando exato pode ter que diferir dependendo do filefrag version)
# filefrag -s -v trim.test
File size of trim.test is 1048576 (256 blocks, blocksize 4096)
ext logical physical expected length flags
0 0 34048 256 eof
trim.test: 1 extent found
Obtenha o dispositivo:
# df trim.test
/dev/mapper/something 32896880 11722824 20838512 37% /
Com essa configuração, você tem um arquivo trim.test filles com yes -pattern em /dev/mapper/something no endereço 34048 com comprimento de 256 blocos de 4096 bytes.
A leitura direta do dispositivo deve produzir o yes -pattern:
# dd bs=4096 skip=34048 count=256 if=/dev/mapper/something | hexdump -C
00000000 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a |y.y.y.y.y.y.y.y.|
*
00100000
Se o TRIM estiver ativado, esse padrão deverá mudar quando você excluir o arquivo. Observe que os caches também precisam ser descartados, caso contrário, dd não relerá os dados do disco.
# rm trim.test
# sync
# fstrim -v /mount/point/ # when not using 'discard' mount option
# echo 1 > /proc/sys/vm/drop_caches
# dd bs=4096 skip=34048 count=256 if=/dev/mapper/something | hexdump -C
Na maioria dos SSD, isso resultaria em um padrão zero:
00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00100000
Se a criptografia estiver envolvida, você verá um padrão aleatório:
00000000 1f c9 55 7d 07 15 00 d1 4a 1c 41 1a 43 84 15 c0 |..U}....J.A.C...|
00000010 24 35 37 fe 05 f7 43 93 1e f4 3c cc d8 83 44 ad |$57...C...<...D.|
00000020 46 80 c2 26 13 06 dc 20 7e 22 e4 94 21 7c 8b 2c |F..&... ~"..!|.,|
Isso porque, fisicamente aparado, a camada criptográfica lê zeros e descriptografa esses zeros para dados "aleatórios".
Se o yes -pattern persistir, muito provavelmente nenhum recorte foi feito. "
Este é o meu script automatizado:
#!/bin/bash
#
# This script is provided "as is" without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability, fitness for a particular purpose, or non-infringement.
#
# License GPL2
#
# by desgua 2014/04/29
function CLEAN {
cd "$pasta"
[ -f test-trim-by-desgua ] && rm test-trim-by-desgua && echo "Temp file removed"
echo "Goodbye"
exit 0
}
trap 'echo ; echo "Aborted." ; CLEAN; echo ; exit 0' INT HUP
if [[ "$(echo $USER)" != "root" ]]; then
read -n 1 -p 'Become root? [Y/n]' a
if [[ $a == "Y" || $a == "y" || $a == "" ]]; then
sudo $0 $1
exit 0
else
echo "
This script needs root privilege.
"
exit 1
fi
fi
name=$(echo $0 | sed 's/.*\///')
if [ $# -ne 1 ]; then
echo "
Usage: $name /folder/to/test/
"
exit 1
fi
pasta=$1
read -n 1 -p 'Use fstrim? [y/N]' a
if [[ $a == "Y" || $a == "y" ]]; then
fs=1
fi
method=
while [[ "$method" != "1" && "$method" != "2" ]]; do
read -n 1 -s -p 'Choose a method:
[1] hdparm (will fail in LUKS on LVM)
[2] filefrag (warning: you may have to force quit - close the terminal - in some cases of success trim if you see an output that never ends)
' method
done
function SDATEST {
disk=$(fdisk -l | grep /dev/sda)
if [ "$disk" == "" ]; then
echo "
fdisk did not found /dev/sda
"
exit 1
fi
}
function TEST {
echo "Entrying /" ; echo
cd $pasta
echo "Creating the file test-trim-by-desgua at $pasta" ; echo
dd if=/dev/urandom of=test-trim-by-desgua count=10 bs=512k
echo "Syncing and sleeping 2 seconds." ; echo
sync
sleep 2
hdparm --fibmap test-trim-by-desgua
lbab=$(hdparm --fibmap test-trim-by-desgua | tail -n1 | awk '{ print $2 }')
echo "As you can see, the file was created and its LBA begins at $lbab" ; echo
echo "Syncing and sleeping 2 seconds." ; echo
sync
sleep 2
echo "Removing file test-trim-by-desgua" ; echo
rm test-trim-by-desgua
trap 'echo ; echo ; echo "Aborted." ; echo ; exit 0' INT
echo "Syncing and sleeping 2 seconds." ; echo
sync
sleep 2
if [[ "$fs" == "1" ]]; then
echo "fstrim $pasta && sleep 2" ; echo
fstrim $pasta
sleep 2
fi
echo "This is readed from sector $lbab: "
hdparm --read-sector $lbab /dev/sda
pass=$(hdparm --read-sector $lbab /dev/sda | grep "0000 0000 0000 0000")
if [[ $pass == "" ]]; then
echo "
Trim failed...
You should see only 0000 0000 0000 0000 ...
"
else
echo "Success!!!"
fi
exit 0
}
function LUKSTEST {
# Reference: https://unix.stackexchange.com/questions/85865/trim-with-lvm-and-dm-crypt#
echo 1 > /proc/sys/vm/drop_caches
cd $pasta
echo "Creating a \"yes\" file."
yes | dd iflag=fullblock bs=1M count=1 of=test-trim-by-desgua
#position='filefrag -s -v test-trim-by-desgua | grep "eof" | awk '{ print $3 }''
position='filefrag -s -v test-trim-by-desgua | grep "eof" | sed 's| ||g ; s|.*255:|| ; s|\.\..*||''
[[ "$position" == "" ]] && echo "Could not find the position of the file. Are you on a LUKS on LVM?" && CLEAN;
device='df test-trim-by-desgua | grep "dev/" | awk '{ print $1 }''
yes='dd bs=4096 skip=$position count=256 if=$device | hexdump -C'
echo "In the next line you should see a pattern like:
00000000 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a |y.y.y.y.y.y.y.y.|
$yes
"
if [[ "'echo "$yes" | grep "y.y.y"'" == "" ]]; then
echo "The pattern could not be checked. Something went wrong. Exiting."
CLEAN;
else
echo "Pattern confirmed."
fi
echo "Removing the temp file."
rm test-trim-by-desgua
echo "Syncing."
sync
sleep 1
if [[ "$fs" == "1" ]]; then
echo "fstrim -v $pasta && sleep 2" ; echo
fstrim -v $pasta
sleep 2
fi
# Drop cache
echo 1 > /proc/sys/vm/drop_caches
echo "In the next line you should **NOT** see a yes pattern like:
00000000 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a 79 0a |y.y.y.y.y.y.y.y.|
If you see, then trim is not working:
'dd bs=4096 skip=$position count=256 if=$device | hexdump -C'"
yes='dd bs=4096 skip=$position count=256 if=$device | hexdump -C'
if [[ "'echo "$yes" | grep "y.y.y"'" != "" ]]; then
echo "TRIM not working."
else
echo "TRIM is working!"
fi
CLEAN;
}
if [[ "$method" == "1" ]]; then
SDATEST;
TEST;
elif [[ "$method" == "2" ]]; then
LUKSTEST;
fi
exit 0