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Questions tagged [ext4]

Ext 4 is a linux filesystem.

Ext4 is a filesystem mostly used under linux. Other versions are ext, ext2 and ext3.

See Wikipedia for details on ext and ext4.

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How to debug very slow (200 sec) fwrite()/ftello()/fclose()?

I have a program which reads 200byte packets from a queue and writes them to a series of two minute files. Data arrives at 6MB/s which equates to 30,000 calls to fwrite() per second. Once in a while the queue would overflow because fclose() would…
Danny
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latency on posix reads()

we have a very latency sensitive application, in the sense that latency spikes on reads are very very bad. I’ve tested XFS and ext4, and writing O_ASYNC to the file and then fdatasync() at the end can lead to 1 second or more spikes in read…
Michael Xu
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Solr / Lucene best file system

I've done some logs indexing benchmark with Solr with Redhat 7.3. The machine included 2 7200 RPM with software RAID 1, 64GB memory and a E3-1240v6 CPU. I was really surprised to find a huge difference in IO performance between ext4 and xfs (see…
Avner Levy
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Disabling journaling for read-only ext4 fs

If journaling is disabled for a read-only ext4 fs can there be any possible side effects? I see an opportunity of saving precious storage quota by doing so.
sob
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Create a cache file which is automatically deleted when partition is nearly full in libc (all file systems) or ext4?

When writing software which needs to cache data on disk, is there a way in libc, or a way which is specific to a certain file system (such as ext4), to create a file and flag it as suitable to be deleted automatically (by the kernel) if the…
Philip Withnall
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How to get mountpoint information from super_block structure

I want to know on which mount point did my device is mounted from super_block structure. In this function I have super_block structure address with me. Is there anyway to know mount point on which this device is…
Spyder
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make_ext4fs corrupts system.img on Android 6.0.1

I am using since Android 4.4 the tool make_ext4fs to repack Samsung system images. make_ext4fs -s -l [size] -a [mount-point] -S [file_contexts] [out_file] [src_folder] This works fine for sparsed file systems up to Android 5.1.1. I need to repack…
Mr. Fish
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What is the fastest way to increase the size of a file in linux on a ext4 filesystem from a C executable without creating holes in the file?

The fastest way to increase the file size that I know of would be to ftruncate() or lseek() to the desired size and write a single byte. That doesn't fit my needs in this case because the resulting hole in the file doesn't reserve space in the file…
John Cashew
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ext4 commit= mount option and dirty_writeback_centisecs

I'm tring to understand the way bytes go from write() to the phisical disk plate to tune my picture server performance. Thing I don't understand is what is the difference between these two: commit= mount option and dirty_writeback_centisecs. Looks…
Alexcool
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How to store "extended attributes" in ext4 inode block as we have inode extra size "i_extra_isize"

As per struct ext4_inode { ..... __le16 i_extra_isize; ..... } I see that this can be used to store extended attributes, given the fact that I am using the inode size = 256 bytes. Few questions: How do I know if my FS inode size is 256 or…
Rohan
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File last access time. How to mount root filesystem with atime,norelatime

I've installed a simple LAMP system based on Debian 7.2.0 (32 bits). On my server I want to know when each of PHP files was used (accessed) by web server. When I check last access times of php files (with command ls -alu), they are wrong. I've…
Marian
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android file.renameTo changes subdir names

I'm having a very strange problem around renaming folders in android and then reading the file again. I could never reproduce this on any or our local test devices and no one I know had a good idea. Open Question: What can it be that changes the…
philipp
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How can I sort a directory by creation date in BASH?

I'm trying to create a simple script to list the 16 most recent folders created in a directory on my nas machine as a way to display the most recent movies added to my collection. the script i am using at the moment is: #!/bin/bash rm -f…
scktt
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Ext JS 4 radio group check event

I am creating a radioGroup in extJS 4 using xtype inside a FormPanel. I am trying to enable/disable a textfield as soon as the radio is checked. { xtype: 'radiogroup', fieldLabel: 'Enable / Disable ', columns: 2, vertical: true, items: [ …
aswininayak
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What does this Linux kernel trace mean?

I’m running a linux server at home which is mostly a file and e-mail server and a digital video recorder. All the data goes on an ext4 partition on a software raid-6. Every now and then (sometimes twice a day, sometimes twice a month) the whole…
Tilo Prütz
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