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3

I found lazytime, a mount option for ext4, that solves this satisfactorily for me. https://lwn.net/Articles/620086/ This mode causes atime, mtime, and ctime updates to only be made to the in-memory version of the inode. The on-disk times will only get updated when (a) when the inode table block for the inode needs to be updated for some non-time ...


0

It's in your reserve block count: ext3: Block count: 256000 Reserved block count: 0 ext4: Block count: 256000 Reserved block count: 12800 the fix: # tune2fs -m 0 e4fs


2

Firstly, writing a sparse image to a disk will not result in anything but the whole of the size of that image file - holes and all - covering the disk. This is because handling of sparse files is a quality of the filesystem - and a raw device (such as the one to which you write the image) has no such thing yet. A sparse file can be stored safely and securely ...


0

Are you wanting to create this image with a 800MB of space, so you can copy to sd cards. But not wanting to wast space when storing the image. If so may I suggest compression, such as bzip. It will depend on unused blocks being initialised to zero though.


-1

Hope I understand the question properly: To shrink a file-system and partition. Use gparted.


5

The easiest way to do this is to create your backing file as a sparse file; that is, make it 1GB with truncate -s 1G disk.img instead of dd if=/dev/zero bs=1048576 count=1024 of=disk.img (or whatever). Nicely, truncate is also far faster. If you do an ls -l on the file, it'll show as 1GB—but that's only its apparent size. du disk.img will give the actual ...


1

I think I know how it works. I connected another disk to my machine because it has a big almost empty partition ~458G . I checked its free space via e2freefrag: HISTOGRAM OF FREE EXTENT SIZES: Extent Size Range : Free extents Free Blocks Percent 64M... 128M- : 6 146233 0.12% 128M... 256M- : 5 322555 ...


1

Ensure you've recursively set the permissions to 777 after you've done the mount. Doing it before will have no effect. Also, please post the error you're getting. You might want to reconsider your choice of ext4 if you're using it as a removable drive. Frustratingly, there's still no option to ignore ownership and permissions on an ext4 filesystem. It's ...


1

You need kernel level tracing to achieve that. There is a large number of tools available to do it with various levels of features, usability and stability including sysdig, ftrace, perf, dtrace4linux, ktap, systemtap and others. You might start with tpoint which, being based on ftrace, shouldn't need anything to be installed (outside the script itself), ...


2

I'm not sure that you can get all of this information from the ext4 driver, because it does not responsible for the disk sectors and other disk geometry, but block device layer sub-sytem in the Linux kernel. I don't see one way to get all information in which you are interesting, because as I see you are in teresting as in low-level stuff and also in high ...


1

Your question is unclear. If you want raw disk I/O profiling (then file system is irrelevant, and you want also to measure swap disk IO) you might have to configure or patch the kernel (I don't know how). Perhaps running Linux thru an hypervisor (like xen) might help. Look also into oprofile On the other hand, if you are interested by file system activity, ...


1

I finally figured out the actual answer when I read the wikipedia entry for XZ (https://en.wikipedia.org/wiki/Xz): One can think of xz as a stripped-down version of the 7-Zip program. xz has its own file format rather than the .7z format used by 7-Zip (which lacks support for Unix-like file system metadata[2]). It is in fact okay to have millions ...



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