XFS file system in linux RHEL 7

XFS File System:

XFS is a high-performance 64-bit journaling file system created by Silicon Graphics, Inc (SGI) in 1993. It was the default file system in the SGI's IRIX operating system starting with its version 5.3; the file system was ported to the Linux kernel in 2001. As of June 2014, XFS is supported by most Linux distributions, some of which use it as the default file system.

FEATURE:

Capacity

XFS is a 64-bit file system.^[13] It supports a maximum file system size of 8 exbibytes minus one byte (2⁶³-1 bytes), but this limitation can be decreased by limitations imposed by the host operating system. 32-bit Linux systems limit the size of both the file and file system to 16 tebibytes.

Journaling

The XFS journal is limited to a maximum size of both 64 KB blocks and 128 MB, with the minimum size dependent upon a calculation of the file system block size and directory block size.In XFS, the journal contains "logical" entries that describe, in a humanly understandable way, what operations are being performed (as opposed to a "physical" journal that stores a copy of the blocks modified during each operation). Journal updates are performed asynchronously to avoid a decrease in performance speed.

Online resizing

XFS provides the xfs_growfs utility to perform online resizing of XFS file systems. XFS filesystems can be grown so long as there is remaining unallocated space on the device holding the filesystem. This feature is typically used in conjunction with volume management, as otherwise the partition holding the filesystem will need enlarging separately. XFS partitions cannot (as of August 2010) be shrunk in place, although several possible workarounds have been discussed.

Atomic disk quotas

Quotas for XFS filesystems are turned on when initially mounted; this fixes a race window that is present with most other filesystems that first require to be mounted and where no quotas are enforced until quotaon is called.

Disadvantage

• An XFS file system cannot be shrunk, which would be useful, for example, in some virtualized environments.
• Metadata operations in XFS have historically been slower than with other file systems, resulting in, for example, poor performance with operations such as deletions of large numbers of files. However, a new XFS feature implemented by Dave Chinner and called delayed logging, available since version 2.6.39 of the Linux kernel mainline, is claimed to resolve this; performance benchmarks done by the developer in 2010 revealed performance levels to be similar to ext4 at low thread counts, and superior at high thread counts.

SOURCE: en.wikipedia.org/wiki/XFS