Disks and filesystems: Difference between revisions
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[[Category:Linux/Unix]] | |||
;badblocks -v- s /dev/sdb >badblocks.log | ;badblocks -v- s /dev/sdb >badblocks.log | ||
:Check a device for bad blocks | :Check a device for bad blocks | ||
;fdisk /dev/sdb | ;fdisk /dev/sdb # Deprecated | ||
:Manage disk partitions | ;gdisk /dev/sdb | ||
:Manage disk (GPT) partitions | |||
;df -h | ;df -h | ||
| Line 10: | Line 13: | ||
;df -i | ;df -i | ||
:Show filesystem inode usage | :Show filesystem inode usage | ||
;df -P | |||
:Report file-system information in parseble format. | |||
;du -shx * | |||
:Report disk usage for all files and directories in the current directory. Do not count files on other filesystems (-x) and do not follow symbolic links (default) | |||
;ls -i <file> | ;ls -i <file> | ||
:Show inode of <file> | :Show inode of <file> | ||
; | ;stat <file> | ||
: | :Show about all there is to know about <file> | ||
;getfacl <file> | |||
:Show the Access Control List (ACL) information for a file or directory | |||
;setfacl -m <nowiki>u:<username>:<perm> <file></nowiki> | |||
:Add <perm> for <username> to <file> | |||
;setfacl -d -m <nowiki>u:<username>:<perm> <dir></nowiki> | |||
:-d makes that all files in <dir> will get the <username>:<perm> added to the ACL | |||
;mount -t <fstype> -o <options> <devicefile> <mountpoint> | ;mount -t <fstype> -o <options> <devicefile> <mountpoint> | ||
:Mount a filesystem (fstype and options can be omitted often) | :Mount a filesystem (fstype and options can be omitted often) | ||
;mount -a | |||
:Mount all filesystems in [[#fstab|/etc/fstab]] with the <code>auto</code> option. | |||
;mount -o loop /path/to/my-iso-image.iso /mnt/iso | ;mount -o loop /path/to/my-iso-image.iso /mnt/iso | ||
:Mount an .iso file | :Mount an .iso file | ||
==fstab== | |||
Configuration file to store mounts. Example for NFS mounts: | |||
;<code><host>:<path> <mountpoint> nfs defaults 0 0</code> | |||
:Enable mount by; <code>mount <mountpoint></code> | |||
:Mount the <path> exported by <host> on directory <mountpoint> using the NFS protocol with default setting (see below), do not automatically backup when dump is executed and do not fsck when mounted at boot time. | |||
;<code><host>:<path> <mountpoint> nfs defaults,noauto 0 0</code> | |||
:Same as above but do not mount at boot-time | |||
Defaults (specified by defaults) are for ext3 filesystems: rw,suid,dev,exec,auto,nouser,async (read/write, set userID, dev?, allow execution of executables, mount during boot and when <code>mount -a</code> is done, only root can mount this, do not wait for the host to have written to storage) | |||
See the [https://en.wikipedia.org/wiki/Fstab fstab wikipedia page] for more. | |||
==Performance== | ==Performance== | ||
The graphical utility '''Disks''' has a benchmark option. | The graphical utility '''Disks''' has a benchmark option. | ||
;dd if=/dev/zero of=./test.tmp bs=1G count=1 oflag=dsync;rm -f ./test.tmp | |||
:Check plain write speed | |||
;dd if=/dev/zero of=./test.tmp bs=512 count=1000 oflag=dsync;rm -f ./test.tmp | |||
:Latency test | |||
On an empty disk you can do: | |||
;dd if=/dev/zero of=/dev/sdb bs=8k count=10k | ;dd if=/dev/zero of=/dev/sdb bs=8k count=10k | ||
:Test disk write speed if no | :Test disk write speed if no filesystem exists | ||
==Misc== | ==Misc== | ||
Latest revision as of 10:23, 10 March 2026
- badblocks -v- s /dev/sdb >badblocks.log
- Check a device for bad blocks
- fdisk /dev/sdb # Deprecated
- gdisk /dev/sdb
- Manage disk (GPT) partitions
- df -h
- Show filesystem block usage in human friendly format
- df -i
- Show filesystem inode usage
- df -P
- Report file-system information in parseble format.
- du -shx *
- Report disk usage for all files and directories in the current directory. Do not count files on other filesystems (-x) and do not follow symbolic links (default)
- ls -i <file>
- Show inode of <file>
- stat <file>
- Show about all there is to know about <file>
- getfacl <file>
- Show the Access Control List (ACL) information for a file or directory
- setfacl -m u:<username>:<perm> <file>
- Add <perm> for <username> to <file>
- setfacl -d -m u:<username>:<perm> <dir>
- -d makes that all files in <dir> will get the <username>:<perm> added to the ACL
- mount -t <fstype> -o <options> <devicefile> <mountpoint>
- Mount a filesystem (fstype and options can be omitted often)
- mount -a
- Mount all filesystems in /etc/fstab with the
autooption. - mount -o loop /path/to/my-iso-image.iso /mnt/iso
- Mount an .iso file
fstab
Configuration file to store mounts. Example for NFS mounts:
<host>:<path> <mountpoint> nfs defaults 0 0- Enable mount by;
mount <mountpoint> - Mount the <path> exported by <host> on directory <mountpoint> using the NFS protocol with default setting (see below), do not automatically backup when dump is executed and do not fsck when mounted at boot time.
<host>:<path> <mountpoint> nfs defaults,noauto 0 0- Same as above but do not mount at boot-time
Defaults (specified by defaults) are for ext3 filesystems: rw,suid,dev,exec,auto,nouser,async (read/write, set userID, dev?, allow execution of executables, mount during boot and when mount -a is done, only root can mount this, do not wait for the host to have written to storage)
See the fstab wikipedia page for more.
Performance
The graphical utility Disks has a benchmark option.
- dd if=/dev/zero of=./test.tmp bs=1G count=1 oflag=dsync;rm -f ./test.tmp
- Check plain write speed
- dd if=/dev/zero of=./test.tmp bs=512 count=1000 oflag=dsync;rm -f ./test.tmp
- Latency test
On an empty disk you can do:
- dd if=/dev/zero of=/dev/sdb bs=8k count=10k
- Test disk write speed if no filesystem exists
Misc
- /dev/null
- The unix black hole. Write always succeeds with no effect at all.
- /dev/zero
- Provides an unlimited amount of null characters (ASCII 0). Can be used for cleaning disks or benchmarking (see #Performance)
- Writing to /dev/zero is the same as writing to /dev/null