[Q] what is /cache and /system ? - Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A

could anyone give me a clear explanation about swap. i found the term /cache and /system. i do not find any clear explanation about where the swap process takes places.
if i use swap2cache script, will the swap happen at sdcard or internal memory?
sory for noob question.

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sony_84 said:
could anyone give me a clear explanation about swap. i found the term /cache and /system. i do not find any clear explanation about where the swap process takes places.
if i use swap2cache script, will the swap happen at sdcard or internal memory?
sory for noob question.
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Swapping:
When the ram has very less free space the operating system moves the low priority processes from the ram and places them in the swap partition to make space for high priority processes .
When those low priority processes attain high priority the operating system moves that process from swap partition and places it in the ram.
This process of moving files to and from ram is defined as swapping and the partition which is used for storing these swapped files is the swap partition.
/cache is a partition which is utilized by programs. Programs place their files which are routinely used in the cache partition to reduce the processing time.
For example:
Gallery app saves all the thumbnails of all the pics and videos in the cache partition for fast access when the app is opened.
/system is the partition where all the operating system files are placed . This partition contains nothing but the files which are needed for the operating system to perform without any intervention by the user (both cache and system are generally write protected).
For example:
The folder C:\windows is the system folder in windows whereas /system is the system partition in android.
When you use the /cache partition for swap space you are using the phone memory and not the external memory.
you might want to google the term "zram" it is some what faster than swap to cache,
it compresses the ram memory and makes way for new processes and when the compressed memory is needed again, it simply uncompress them right in the ram memory. as it works with the ram memory itself it is considered to be the fastest.
(please correct me if I am wrong)
And don't be sorry for a noob question. Every experienced developer must have started as a noob and we are here to learn and share so questions are always welcome!
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sent from my smultron

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gouthamthemostwanted said:
When the ram has very less free space the operating system moves the low priority processes from the ram and places them in the swap partition to make space for high priority processes .
When those low priority processes attain high priority the operating system moves that process from swap partition and places it in the ram.
/cache is a partition which is utilized by programs. Programs place their files which are routinely used in the cache partition to reduce the processing time.
/system is the partition where all the operating system files are placed . This partition is nothing but the files which are needed for the operating system to perform without any intervention by the user (both cache and system are generally write protected).
When you use the /cache partition for swap space you are using the phone memory and not the external memory.
you might want to google the term "zram" it is some what faster than swap to cache,
it compresses the ram memory and makes way for new processes when the compressed memory is needed again it simply uncompress them right in the ram memory. as it works with the ram memory itself it is considered to be the fastest.
(please correct me if I am wrong)
PRESS THANKS IF I HELPED YOU!
sent from my smultron
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great explanation brother, the only bad swap, in which damages the lifetime of sd memory, I remember when I used my old w8 swap took longer to copy files from PC to phone and vice versa, so I do not recommend doing swap is my simple opinion :highfive:

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Swapping to external memory is never recommended unless you badly need swap partition and it's the only option you have. Swapping to external memory reduces the life of the external memory very quickly since swapping pages to and from external memory increases the number of read/write cycle count of the external memory which is a very important factor in the external memory's life.
PRESS THANKS IF I HELPED YOU!
sent from my smultron

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gouthamthemostwanted said:
Swapping to external memory is never recommended unless you badly need swap partition and it's the only option you have. Swapping to external memory reduces the life of the external memory very quickly since swapping pages to and from external memory increases the number of read/write cycle count of the external memory which is a very important factor in the external memory's life.
PRESS THANKS IF I HELPED YOU!
sent from my smultron
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so, when we use swap to /cache or /system , will it reduce the life of our internal memory ?? it means that it will break our gadget someday

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sony_84 said:
so, when we use swap to /cache or /system , will it reduce the life of our internal memory ?? it means that it will break our gadget someday
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Theoretically yes,
It depends on how often the swapping takes place and practically in very extremely rare cases the internal memory fails due to swapping. (someone correct me if I am wrong)
External memory is designed in a way to have large space so it's transfer speed is the lowest.
Internal memory is embedded flash memory and has lower capacity compared to external memory and it has higher transfer speeds compared to external memory.
Ram is volatile memory designed for high speed data transfer.
If you are very much concerned about your life of external memory and internal memory then zram is your only option.
PRESS THANKS IF I HELPED YOU!
sent from my smultron

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gouthamthemostwanted said:
Theoretically yes,
It depends on how often the swapping takes place and practically in very extremely rare cases the internal memory fails due to swapping. (someone correct me if I am wrong)
External memory is designed in a way to have large space so it's transfer speed is the lowest.
Internal memory is embedded flash memory and has lower capacity compared to external memory and it has higher transfer speeds compared to external memory.
Ram is volatile memory designed for high speed data transfer.
If you are very much concerned about your life of external memory and internal memory then zram is your only option.
PRESS THANKS IF I HELPED YOU!
sent from my smultron
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if it's so , I just need to apply zram script ?

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sony_84 said:
if it's so , I just need to apply zram script ?
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yes.
this is the script to be executed to enable zram.
i guess it should work with all kernels for our device (i guess)
i took it from rage kernel thread thread so the credits goes to DuMOHsmol
the script must be run at boot every time (copy it to etc/init.d folder)(provided you have init.d support).
HIT THANKS IF I HELPED YOU!

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gouthamthemostwanted said:
yes.
this is the script to be executed to enable zram.
i guess it should work with all kernels for our device (i guess)
i took it from rage kernel thread thread so the credits goes to DuMOHsmol
the script must be run at boot every time (copy it to etc/init.d folder)(provided you have init.d support).
HIT THANKS IF I HELPED YOU!
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Click to collapse
this is working great.
just to make sure, is this safe for internal and external memory??

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Ya man! Nothing to worry. The main concept behind zram is to optimize the ram memory for system on chip devices (devices whose hardware can't be upgraded).
PRESS THANKS IF I HELPED YOU!
sent from my smultron