SliTaz Forum

Root filesystem in RAM

(4 posts) (3 voices)

• Started 10 years ago by KairiTech
• Latest reply from KairiTech
• This topic is not a support question

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1. 

   KairiTech
   

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   Is the root filesystem stored in RAM uncompressed or are the files only expanded when they are accessed for the first time?

   Posted 10 years ago #
2. 

   Anonymous
   

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   As no one else has answered, I'm not here too often, I believe they are copied to ram uncompressed.
   If you check ram usage against the linuxfs (& kernel?) sizes, that should confirm, (or not).
   (In a terminal run 'free -m')
   Hope that helps.

   Posted 10 years ago #
3. 

   Bellard
   

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   Key Master

   The root filesystem is stored in RAM uncompressed in the buffer cache as tmpfs.

   Posted 10 years ago #
4. 

   KairiTech
   

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   Thanks for the confirmation but while I was awaiting an answer I found a way to move an existing install's root uncompressed to RAM on the fly:

   Decompress the initramfs to a temporary directory:
   

   mkdir /tmp/initramfs/
   cd /tmp/initramfs/
   gzip -d < /mnt/boot/initramfs-linux.img | cpio –i

   Add the code below to init immediately after the real root is mounted:
   

   echo
   echo "  || Press a key to load root filesystem to RAM..."
   echo
   if read -t 3 -n 1 k
      then
         mkdir /tmp/real_root/
         mount --move /new_root/ /tmp/real_root/
         mount --verbose -t tmpfs -o size=50% none /new_root/
         echo
         echo "  ||  Copying root filesystem to RAM..."
         echo
         cp -a /tmp/real_root/* /new_root/
         umount /tmp/real_root
         read -p "  ||  Done! Press [Enter] to continue..." RESP
      else
         clear
         echo
         echo "  ||  To late! Normal boot in progress..."
         echo
   fi

   Re-compress the initramfs:
   

   find . | cpio -o -H newc | gzip -9 > /mnt/boot/initramfs-linux.img
   
   cd ~

   This could easily be adapted to any distro atop any storage regime. Just remember that only updates while booted to the real root are persistent but the good thing is they will follow through to the RAM root the next time you boot into it.

   The above is redundant with respect to SliTaz but it may provide some clarity on how to go about having the root filesystem loaded to RAM for increased system performance.

   Posted 10 years ago #

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