This change was made possible with the combination of extent patches which uses bit physical block numbers. Other metadata changes, such as in the super-block structure, were also made to support the bit block number.
A journaling filesystem is a filesystem that maintains a special file called a journal that is used to repair any inconsistencies that occur as the result of an improper shutdown of a computer. In Ext4 you get an additional advantage of disabling journaling feature which can help slightly improve the performance of machine for users with special requirements and lesser workloads.
Block allocator is the one that decides which free blocks will be used to write the data. Ext3 allocator allocates one block at a time for any data in the filesystem so you can imagine the amount of CPU and time occupied while writing a data for MB as shown in above calculation.
Ext4 uses Multiblock Allocator which allows many blocks to be allocated to a file in a single operation, in order to dramatically reduce the amount of CPU usage searching for many free blocks in the filesystem.
Also, because many file blocks are allocated at the same time, a much better decision can be made to find a chunk of free space where all of the blocks will fit. This is a feature where writing new data on the filesystem is delayed as much as possible as compared to ext3 filesystems which immediately starts looking for free block and aloocates as soon as possible. Combined with Multiblock Allocation a large no of block can be allocated at the same time by knowing the size of block required, a suitable chunk of free space can be looked for and allocated to it instead of picking up a single free block everytime.
This will reduce CPU time spent in block allocation increasing the performance. Ext4 will support online fragmentation which is performed by creating a temporary inode, using multiple block allocation to allocate contiguous blocks to the inode, reading all data from the original file to the page cache, then flushing the data to disk and migrating the newly allocated blocks over to the original inode.
Why we need defragmentation? There happens a case when you have multiple files in your filesystem. Now these data are stored as small blocks.
Searching for 16TB ext4 limit on google reveals a plethora of people looking for a solution. There is certainly a mistake on specification about number of sub-directories that can be created under a directory in ext4 files. You have mentioned it as 64, but its actually 6,40, 6 lakhs 40 thousands.
I just tested by increasing the condition value in my script to , and it did created all the sub-directories. All your documentation on linux are so helpful. I was wondering, if you could provide some documentation on linux servers hardening centos latest version. EXT4 already has 48 bit block addressing. Whoever took their time to compile this, deserves a pat on the back. Well Done. I have been looking out for a reliable home-NAS.
Much of my folder structure is nested in folders which makes sense from a filing perspective , but not in a backup system. I have been looking at the Synology set of NAS systems. Really a Very Nice documents Specially when a beginner like me want to know difference between all the file systems in Linux. Thank you. PS if any one use android x86 i suggest use ext2 or 3 format because ntfs and fat32 suck at android compitablity. If I have a kernel version older than 2.
Do I need to patch my kernel or a complete kernel upgrade is needed. So use. Save my name, email, and website in this browser for the next time I comment. Notify me of followup comments via e-mail. All rights reserved Terms of Service. This article explains the following: High level difference between these filesystems. I got it later. You can call it filesystem or partition, nothing makes sense, becasue everything is a file in Linux.
I think you mean to say how to change Linux partition Label names, if yes so, you can read this article that explains how to change or modify partition label names on Linux filesystem. A nice way is to manage LVM through ssm. Only one step-we can create a logical volume and volume group, choose file system type. Have a question or suggestion? Please leave a comment to start the discussion. Please keep in mind that all comments are moderated and your email address will NOT be published.
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You can also subscribe without commenting. This site uses Akismet to reduce spam. Connect and share knowledge within a single location that is structured and easy to search. What are the big differences between ext3 and ext4 from a generic user's perspective? I heard that sticking with ext3 is wiser. Is that true?
But, ext3 has this privilege. A few years ago I'd say stick with ext3 but nowadays ext4 is better. A recent May 16, round up from thegeekstuff. A very good comparison from on linuxologist. If you need to share a partition with Windows you will need ext3. I myself have given up on Windows so I have everything set to ext4 and use a USB stick to transfer data to a Windows machine mainly at work.
The only reasons I can think of at the current time not to use ext4 are compatibility with older systems, and, last time I tried it, ext4 had problems with losing data when used on flash media ie. Thumb drives et cetra. That second one I haven't tested in about six months, so it may have been fixed. Otherwise, the performance and reliability are large improvements over ext3. Ubuntu Community Ask!
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