Archive for 'File System'

Hard Link vs Soft Link

Once again, one of the very basic question asked in the interviews, What is the difference between Hard links and Soft links. You can explain few basic things, but emphasizing on internals about the linux filesystem, is something which can impress the interviewer.

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Understanding Linux / Unix Filesystem Inode

Inode, short form of Index Node is what the whole Linux filesystem is laid on. Anything which resides in the filesystem is represented by Inodes. Just take an example of an old school library which still works with a register having information about their books and their location, like which cabinet and which row, which books resides and who is the author of that book. In this case, the line specific to one book is Inode. In the same way Inodes stores objects, which we will study in detail below.

So, in the linux system, the filesystem mainly consists of two parts, first is the metadata and the second part is the data itself. Metadata, in other words is the data about the data. Inodes takes care of the metadata part in the filesystem.

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TechTip: Find Physical Location of a file on disk

When you create a file, it's stored in different blocks/locations of the filesystem/disk depending upon the size of the file. Though you don't need to know the physical location of the disk in normal scenarios, but you might need it in things like, to understand the filesystem layout and how file is stored on the filesystem or to do performance tests.

Finding the physical location of the file can be achieved by following commands:

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gvfsd-metadata using 100% CPU

I am not sure whether it's a bug or not, but this is one of the problem which is seeing in a lot of ubuntu systems. I looked around and found that the main cause for this is the filesystem getting filled up. Once the filesystem is full, then this process starts and start hogging the CPU completely. Running the "top" command will confirm you this, as this process will be running on top of everything and will be eating 100% CPU.

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