A filesystem is a method of storing and organizing computer files and their data.

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Booting using initramfs instead of uramdisk

I am working on Zynq Microzed board. It is booting perfectly with uramdisk.image.gz but I trying to boot it with initramfs.cpio. In this regard I have made following changes in header files of ...
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106 views

Hiding data in filesystems

I want to hide some files such that not even 'ls -a' can find it. I'm not talking about adding '.' in front of the filename. I was thinking if I could create separate system calls for accessing those ...
3
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2answers
456 views

Make part of read-only filesystem writable

I have a filesystem on flash using jffs2. I would like to mount this filesystem read-only, except for a single folder that I would like to be writable. Is this possible without resorting to something ...
3
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1answer
51 views

Does du or df perform caching?

I was wondering if there is any caching done with these utilities. I assume not, but not positive. Are there any typical similar utilities that do use caching to speed up results on subsequent runs? ...
3
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1answer
38 views

filesystem that works under qemu and I can mount on my host

I'm using qemu for different kind of tasks, I would like to pick a filesystem that is both qemu-compatible and easy to mount under my host. I already discarded both qcow and qcow2 because apparently ...
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5answers
523 views

Is there a more succinct alternative to piping to wc for counting files in a directory

If I do ls -1 target_dir | wc -l, I get a count of files in a directory. I find this a bit cumbersome. Is there a more elegant or succinct way?
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4answers
193 views

How to check physical device contents

I got a server with 2 hard drives. I would like to know what is on 2nd drive. How would I list all contents on physical device ? lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT xvda 202:0 0 ...
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3answers
856 views

EXT3: If block size is 4K, why does ls -l show file sizes below that?

If you run ls -l on a file that contains one letter, it will list as 2B in size. If your file system is in 4k blocks, I thought it rounded files up to the block size? Is it because ls -l actually ...
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45 views

Unable to make file system writtable no matter what

I have a flash card SanDisk of a camera which I plug in into my computer: $ lsblk mmcblk0 179:0 0 3.7G 1 disk └─mmcblk0p1 179:1 0 3.7G 1 part $ mount /dev/mmcblk0p1 on ...
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1answer
88 views

How to make an unallocated space “exist”?

I have Ubuntu and Windows installed together. I'm going to install Arch also along with them. For now, I what them to live there all together in my computer. I have the following: I'd like to ...
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2answers
298 views

Unable to remove the files from an usb drive (neither by dd /dev/zero nor by rm -r)

I have a flash usb drive and up till now it has worked well. Recently I recorded iso to it using dd. Now I want to delete it. $ lsblk NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT ....... sdb ...
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1answer
454 views

“Converting” a filesystem from ext3 to ext4

I've read on some Q&A on this website that one can "convert" an ext3 filesystem to ext4 without formatting, by issuing tune2fs -O extents,uninit_bg,dir_index /dev/dev-name And then running ...
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1answer
334 views

How to reset password on an encrypted fs?

I've got a laptop which I haven't used since the last summer vacation: I did put Debian 7 on it and used Debian's feature to fully encrypt the disk, besides a tiny bootloader (or a tiny partition) I ...
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1answer
95 views

Files that do not exist, prevent me from deleting them, corrupted filesystem

Well... It's about on an OS X system (hfs+), but that's unix after all to. :p system has become unbootable, due to a filesystem error... fsck.hfsplus fails because .... ... ** Checking ...
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1answer
66 views

Starting my own application at the startup

I am working on zc702 board having ARM Cortex A 9 processor. I have a binary that I got after cross-compilation for ARM (LED blinking). Now I want that this file should execute as soon as the the ...
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0answers
67 views

Optimal rootflags for rootfs for ext4 file system running on USB thumdrive [closed]

I have made myself a bootable USB Debian 7 thumbdrive, using debootstrap. It boots nicely - but occasionally freezes for a bit. I can see the load average is much higher than the running tasks should ...
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2answers
77 views

How can I find out about “rootfs”

Running Debian 7; when I execute a cat /etc/mtab I can see all sorts of useful information about the filesystems that are mounted, such as the filesystem and options used to mount then; however ...
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1answer
220 views

Why do deleted files continually reappear?

I've been having a strange issue recently, where I would delete files from a location (i.e. Desktop), and then empty the Trash. However, a day or so later (I'm not sure exactly what triggers it), the ...
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1answer
21 views

What is the encryption function in Encfs?

I'm a newbie at Encfs. After I read a paper about Encfs, I figured out there is a Encryption layer in Encfs. So I tried to find exact encryption function. but I couldn't find that because there are ...
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25 views

How is default readahead value determined

I have two different devices running XFS and the default readahead value set differs between the two disks. Why is that ? How is the default size computed ? Is it device dependent ? I might also add ...
4
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1answer
111 views

Backup of a ubi file system with dd?

A have a root file system (file system - image containinf folder structure and content) on a flash drive. The flash drive uses UBI as the underlying file system file system - the way the data blocks ...
5
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3answers
136 views

What filesystem metadata operations are actually journaled in ext4 & xfs?

I can't find a simple, straight answer about which filesystem metadata operations are actually persisted to the ext4 & xfs filesystem journals. Note that I am not inquiring about what POSIX ...
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2answers
144 views

Moving unallocated space from Extended partition to create a Primary partition

This is my partition structure : I want to create another primary partition from that unallocated space. If I shrink sda2 to a size less than what I needed for to create another primary partition, ...
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3answers
155 views

Speed up copying 1000000 small files

I have 1000000 4-20 kb files in a dir. I need to copy that dir. But it seems I have to do a seek for each files so this takes quite a while. Is there a way in which I can speed this up? I am ...
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0answers
88 views

Replacing default initramfs with my own

I followed this article to develop my own sample intramfs.cpio Now I have to put this in my kernel and compile. The procedure that I follw for petlinux is that I first run petalinux-config (and ...
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1answer
29 views

The libblkid library: any way to use it with blocks in the core memory?

I know how to use the libblkid library to analyze existing block devices. I'd like to use it to analyze a memory extent before I write it to the block device. Something like that: char block[4096]; ...
2
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1answer
47 views

The libblkid library: what is the 'blkid_superblocks_get_name' function for?

I'm trying to use the libblkid library to analyze various filesystems on a block device from a C/C++ program, and it works well. However I'm confused with the blkid_superblocks_get_name function from ...
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8answers
836 views

Do I require a file system when I do not want to store any data

I asked a question here Is it mandatory to have a file system One of the comments is : how a system without file system would work on linux as even a printer or ethernet card is considered as ...
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1answer
137 views

Best parameters for ext4 filesystem to handle virtualbox disk images

I have ext4 partition, which holds disk image files VirtualBox works with. They all are fixed-size images (i.e. files never change their size). They are defragmented as much as possible (with ...
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1answer
113 views

File has bytes - appears to be empty

I'm having the following problem: Some text files (also some binary files) on my system are listed with the correct file size but when I open them, they appear empty. >ls -la -rw-rw-r-- 1 user ...
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224 views

No filesystem could mount root, tried: jffs2

CPU: ARM Cortex A-9 This is the kernel command line that I appears in configuration menu root=mtd:jffs2 rw rootfstype=jffs2 console=ttyps0,115200 I have put three files in flash: BOOT.BIN in mtd0 ...
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4answers
317 views

Why is writing so slow on raw device, and so fast on filesystem (USB key)?

I have a USB key that I am trying to benchmark quick'n'dirty on Linux. I'm testing write bandwith. dd on raw partition I created a partition starting at sector 2048, then did a 4 GB sequential ...
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39 views

Verify semantic integrity of filesystem

I just started up my linux box to find that one of my filesystem's had errors: I had to login as root to run fsck and hit y repeatedly. There were a lot of errors. So many that I used silly putty and ...
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2answers
442 views

Is that possible to integrate zip and tar.gz files as directory into the file system

I wonder if there is a way to integrate (it's a bit different from mounting, I think) compressed files as directories into the file system? E.g., one could download a compressed-file.tar.gz to his ...
3
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1answer
59 views

ext4 inode size, shown by dumpe2fs

Manpage about mke2fs says "mke2fs creates 256-byte inodes by default". I've formatted my small (320MB) test partition with command: sudo mkfs -t ext4 /dev/sdc1 The defaults for the mke2fs are ...
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100 views

Most accurate disk usage report? [duplicate]

Since disk space is allocated in blocks, is it a more accurate representation of the actual space consumed by a directory to report it in blocks vs bytes? If a file of size 1,025 bytes resides on a ...
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299 views

ext3 Filesystem shows full to most apps, but only 77% full to DF

Var is showing as full to many apps like Nagios, Puppet, and the LVM tools (pvs, vgs, etc) df -h output 6.0G 4.3G 1.4G 77% /var vgs output /var/lock/lvm/V_rootvg:aux: open failed: No space ...
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1answer
136 views

Ext2 block structure: size of reserved GDT Blocks

In every publication I found about ext2, the structure of a block group is defined as following: Super Block: 1 block Group Descriptor: N blocks Data Bitmap: 1 block Inode Bitmap: 1 block Inode ...
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70 views

Monitor when read/write on metadata or mmaped files hit the disk

On a server hosting a wide range of websites, I often see IO becoming a bottleneck without being able to identify the processes responsible of IO operations with tools such as iotop, iostat or sar. I ...
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5answers
238 views

Get space details without drive names

if there a way to get drives space details without drive names. E.g., the output of df -h Filesystem Size Used Avail Use% Mounted on /dev/sda3 20G 15G 4.2G 78% / ...
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2answers
849 views

what does it mean by cold cache and warm cache concept?

I read a paper and it used terms “cold cache” and “warm cache”. What does it mean by cold cache and warm cache concept? I visit this but I need something more.
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2k views

How to tell which file is original if hard link is created

For example, I have a file myold_file. Then I use ln to create a hard link as mylink: ln myold_file mylink Then, even by using ls -a, I cannot tell which is the old one. Is there anyway to tell?
2
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1answer
73 views

Why store program code in /var/cache?

I have inherited a Java / Tomcat stack, running on Ubuntu. It has crashed and I am trying to restart it. The program code seems to be using a config file which I have found on the file system. The ...
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1answer
92 views

Unable to format a CF card

I have a compact flash card formatted to FAT16. I am unable to format it to any other file system. I used GParted to format the card to ext2 for example, after I do that, the file system becomes ...
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0answers
31 views

Fedora Update and /var space problems

I have just installed Fedora 20 (KDE) and the system informed me that I should get updates. I checked everything and accepted to install additional ones. It got to a certain point (around 10%) and it ...
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1answer
74 views

“hard-linking” parts of a big file in which only a small part has changed

I use rsync to make backups: rsync -a --link-dest=PATHTO/$PREVIOUSBACKUP $SOURCE $CURRENTBACKUP This way I save space due to using hard links. The problem appears when I need to backup a huge file ...
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3answers
3k views

What happens when I run the command cat /proc/cpuinfo?

What happens when I write cat /proc/cpuinfo. Is that a named pipe (or something else) to the OS which reads the CPU info on the fly and generate that text each time I call it?
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303 views

dumpe2fs - lifetime writes - what is it

For example, if I run: sudo dumpe2fs /dev/sda1 I get detailed information about the partition. I'm confused about this part, Lifetime writes, returns the following for my boot partition: Lifetime ...
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3answers
224 views

Why do ls and hexdump disagree about my file size?

I have a file I created (in vim), for testing purposes (testing UTF-8 output in an SSH client). Odd things, however, are happening to this file. I wondered what bytes were in the file, so I used ...
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1answer
39 views

Specify a fallback file for a broken symbolic link

I want to create a symlink, foo.txt, needed at system startup, to another file, bar.txt on a different mount point. The mounted partitions are different physical drives as well. ln -s /baz/bar.txt ...