Difference between revisions of "Disks and filesystems"
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;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> | ||
− | |||
− | |||
− | |||
;mount -t <fstype> -o <options> <devicefile> <mountpoint> | ;mount -t <fstype> -o <options> <devicefile> <mountpoint> | ||
Line 23: | Line 26: | ||
: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> | ||
+ | |||
+ | Now you can mount by; <code>mount <mountpoint></code> | ||
+ | |||
+ | De line above means; 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. | ||
+ | |||
+ | 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]. | ||
==Performance== | ==Performance== |
Latest revision as of 15:13, 23 October 2022
- badblocks -v- s /dev/sdb >badblocks.log
- Check a device for bad blocks
- fdisk /dev/sdb
- Manage disk 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>
- mount -t <fstype> -o <options> <devicefile> <mountpoint>
- Mount a filesystem (fstype and options can be omitted often)
- 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
Now you can mount by; mount <mountpoint>
De line above means; 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.
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.
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