22.Explain memory and virtual file system in Linux.
Ans.
1. These file systems do not exist on disk in the same way that traditional file systems do, they either exists entirely in the system memory or they are virtual because they are an interface to system devices.
2. cramfs:
cramfs is designed to cram a file System onto a small flash memory device, so it is small, simple and able to compress things well.
The largest file size is 16MB and the largest file system size is 256MB since cramfs is so compressed, it isn’t instantly updateable.
3. tmpfs:
tmpfs is structured around the idea that whatever is put in the /tmp file system is accessed again shortly, tmpfs solely in memory, so what you put in /tmp doesn’t persist between reboots.
4. ramfs:
ramfs is basically cramfs without the compression.
5. romfs:
This is a read only file system that is mostly used for initial ramdisks of installation disks.
It was designed to take up very little space, so you could fit a kernel and some useful code into a small disk.
6. proc:
proc is a virtual file system that acts as an interface to the kernel’s internal data structures.
Proc can be used to get detailed information about a system’s hardware and to change kernel parameters at runtime.
7. /dev/pts:
It is a lightweight version if devfs, instead of having all the device files supported in the virtual file system, it provides support for only virtual pseudoterminal device files.
8. devfs:
The device file system (devfs) is another way to access “real” character and block special devices on your root file system, devfs enables device drivers to register devices by name.
9. sysfs:
Sysfs is a virtual file system that acts as an interface to the kernel’s internal data structures information is stored in the /sys directory and can be used to get details about a system’s hardware and to change kernel parameters at runtime.
Ans.
1. These file systems do not exist on disk in the same way that traditional file systems do, they either exists entirely in the system memory or they are virtual because they are an interface to system devices.
2. cramfs:
cramfs is designed to cram a file System onto a small flash memory device, so it is small, simple and able to compress things well.
The largest file size is 16MB and the largest file system size is 256MB since cramfs is so compressed, it isn’t instantly updateable.
3. tmpfs:
tmpfs is structured around the idea that whatever is put in the /tmp file system is accessed again shortly, tmpfs solely in memory, so what you put in /tmp doesn’t persist between reboots.
4. ramfs:
ramfs is basically cramfs without the compression.
5. romfs:
This is a read only file system that is mostly used for initial ramdisks of installation disks.
It was designed to take up very little space, so you could fit a kernel and some useful code into a small disk.
6. proc:
proc is a virtual file system that acts as an interface to the kernel’s internal data structures.
Proc can be used to get detailed information about a system’s hardware and to change kernel parameters at runtime.
7. /dev/pts:
It is a lightweight version if devfs, instead of having all the device files supported in the virtual file system, it provides support for only virtual pseudoterminal device files.
8. devfs:
The device file system (devfs) is another way to access “real” character and block special devices on your root file system, devfs enables device drivers to register devices by name.
9. sysfs:
Sysfs is a virtual file system that acts as an interface to the kernel’s internal data structures information is stored in the /sys directory and can be used to get details about a system’s hardware and to change kernel parameters at runtime.
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