8.6 Flashcards
The area of a hard disk to which new data can be written
free disk space
A bad block is a section on a disk drive to which data can no longer be written to read from.
bad blocks
Displays the free space in the partition holding the specified directory. If no directory is given, the space available on all currently mounted file systems is shown. Disk space is shown in 1 K blocks by default.
df
Displays files and file sizes in and below a specified directory.
du
Displays open files in the file system
isof
Checks and optionally repairs one or more Linux file systems
fsck
Prints super block and block information for an ext2, ext3, or ext4 file system. This includes information for each sector on the partition about sector type, block ranges, inode information, free blocks, and similar information
dumpe2fs
Adjusts tunable file system parameters on ext2, ext3, and ext4 file systems. Some of the adjustable parameters include volume label, reserved blocks, inode sizes, and journaling. Tune2fs can also implement access control lists for individual users
tune2fs
An ext2/ext3/ext4 file system debugger. Can be used for information gathering about target partitions, including directory listings with deleted file entries. Also allows file system modification and deleted file recovery.
debugfs
Monitors system I/O device loading by observing the time devices are active in relation to their average transfer rates. The iostat command generates reports that can be used to change system configuration to better balance the input/output load between physical disks. Running iostat without any options displays CPU usage and I/O statistics in the form of how much has been written per second and in total.
iostat
This tool generates various I/O patterns and lets you monitor I/O speed and latency in real time. this tool shows disk latency in the same way as ping command shows network latency on Linux or Unix-like system.
ioping
A bad sector or block is a section on a disk drive to which data can no longer be written to read from. Included by most Linux distributions, badblocks is used to search for bad blocks on a device (usually a disk partition), where the device is the special file corresponding to the device
badblocks
This command is used to copy the metadata (such as (filenames, file sizes) from an XFS files system to a file, but can only be used to copy unmounted file systems, or read-only mounted file systems.
Be aware that by default, xfs_metadump obfuscates most file (regular file,
directory and symbolic link) names and extended attribute names to
allow the dumps to be sent without revealing confidential
information.
xfs_metadump
is the simplest scheduler. It places all I/O requests into a First in, First Out (FIFO) queue. In addition, read/write requests of a similar purpose are also combined to reduce the number of disk operations and increase the length of system calls. This scheduler is often used for systems that do not need an I/O scheduler. For example, a virtual machine (VM) is running on a host computer which is already using its own I/O scheduler
noop
The Deadline scheduler creates a read queue and a write queue. Since each I/O request has an associated time stamp (used by the kernel for an expiration time), the Deadline scheduler utilizes this time stamp to push I/O request that have reached their deadline to their highest priority.
The default Deadline values are 500 ms for read operations and 5,000 ms for write operations. If needed, these values can be adjusted. Because of these values, the Deadline scheduler is often considered the optimal scheduler for read-heavy workloads.
Deadline
