UNIX for Dummies Questions & Answers

Hi guys,

It has been more than 2 month i switched to linux but i m still very much confused how linux handles and names the partitions.

I have gone through couple of beginners material and found linux doesnt treat partitions as c: and d: instead it uses /dev/hda1 /dev/hda2 hda3 .But now i have come across something like dev/sda1 dev/sda5 tmpfs

Please find output of df -h
I have few questions regarding the same.
1)Why there is no sda2 sda 4 present?
2)What is tmpfs ?
3)What is the difference between sda and hda
4)I also heard there is something as LVM.(How do i know whether my drives are LVM supported or not?
If they are supported how do i extend the drives.

I know these are pretty basic for advance user but i m still a learner in linux . Please help.

tempfs is a temp file system in memory - more like a ram disk (not to be confused with swap space)

hda - normal IDE disks
sda are disks using SCSI emulation built into the kernel
you can partition (and hence number the partitions) differently during the install phase - all depends on how you partitioned your disk

Does this means if i have 2 gb as my physical memory space and if i allocate tmpfs 1 gb then i can only use 1 gb of my physical memory?
Where would i need tmpfs(Practical usage of it)?

Instead of allocating a fixed amount of memory for exclusive use as a file system, tmpfs file system
is dynamic depending on use, allowing the system to decide the optimal use of memory

physical memory gets reduced and then your into the realms of swapping / swap space etc

Does this mean i can use it dynamically whenever required and all the data in tmpfs get flushed incase i restart the system?

correct

Regarding the last question, LVM is a method for managing disks where you can assign physical volumes to volume groups (a group of physical disks) and then split the volume group into partitions as if it were a single disk, each division is called a logical volume.

You can easily resize a LV on the fly (e.g. if you run out of space), attach more disks to the VG, create new partitions, etc.

To the eyes of the kernel there is no difference between a regular partition and a Logical Volume


Linux LVM