XFS is a high-performance journaling file system created by Silicon Graphics, Inc. XFS is particularly proficient at parallel IO due to its allocation group based design. This enables extreme scalability of IO threads, filesystem bandwidth, file and filesystem size when spanning multiple storage devices.
- 1 Installation
- 2 Data corruption
- 3 Integrity
- 4 Performance
- 5 Troubleshooting
- 6 See also
The tools to manage XFS partitions are in thepackage, which is included in the default base installation.
If for whatever reason you experience data corruption, you will need to repair the filesystem manually.
Repair XFS Filesystem
First unmount the XFS filesystem.
# umount /dev/sda3
Once unmounted, run thetool.
# xfs_repair -v /dev/sda3
Online Metadata Checking (scrub)
xfs_scrub asks the kernel to scrub all metadata objects in the XFS filesystem. Metadata records are scanned for obviously bad values and then cross-referenced against other metadata. The goal is to establish a reasonable confidence about the consistency of the overall filesystem by examining the consistency of individual metadata records against the other metadata in the filesystem. Damaged metadata can be rebuilt from other metadata if there exists redundant data structures which are intact.
xfs_scrub_all.timer: the timer runs every Sunday at 3:10am and will be triggered immediately if it missed the last start time, i.e. due to the system being powered off.
Based upon CRC32 it provides for example additional protection against metadata corruption during unexpected power losses. Checksum is enabled by default when using 3.2.3 or later. If you need read-write mountable xfs for older kernel, It can be easily disabled using the
-m crc=0 switch when calling .
# mkfs.xfs -m crc=0 /dev/target_partition
The XFS v5 on-disk format is considered stable for production workloads starting Linux Kernel 3.15.
For optimal speed, just create an XFS file system with:
# mkfs.xfs /dev/target_partition
Yep, so simple - since all of the "boost knobs" are already "on" by default.
Also seefor details of all available mount options.
allocsizevalues, etc. The following articles may provide additional details about those flags:
Stripe size and width
If this filesystem will be on a striped RAID you can gain significant speed improvements by specifying the stripe size to thecommand.
On some filesystems you can increase performance by adding the
noatime mount option to the
/etc/fstab file. For XFS filesystems the default atime behaviour is
relatime, which has almost no overhead compared to noatime but still maintains sane atime values. All Linux filesystems use this as the default now (since around 2.6.30), but XFS has used relatime-like behaviour since 2006, so no-one should really need to ever use noatime on XFS for performance reasons.
nodiratime, so there is never a need to specify nodiratime when noatime is also specified.
Although the extent-based nature of XFS and the delayed allocation strategy it uses significantly improves the file system's resistance to fragmentation problems, XFS provides a filesystem defragmentation utility (xfs_fsr, short for XFS filesystem reorganizer) that can defragment the files on a mounted and active XFS filesystem. It can be useful to view XFS fragmentation periodically.
improves the organization of mounted filesystems. The reorganization algorithm operates on one file at a time, compacting or otherwise improving the layout of the file extents (contiguous blocks of file data).
Inspect fragmentation levels
To see how much fragmentation your file system currently has:
# xfs_db -c frag -r /dev/sda3
To begin defragmentation, use thecommand:
# xfs_fsr /dev/sda3
Free inode btree
Starting Linux 3.16, XFS has added a btree that tracks free inodes. It is equivalent to the existing inode allocation btree with the exception that the free inode btree tracks inode chunks with at least one free inode. The purpose is to improve lookups for free inode clusters for inode allocation. It improves performance on aged filesystems i.e. months or years down the track when you have added and removed millions of files to/from the filesystem. Using this feature does not impact overall filesystem reliability level or recovery capabilities.
This feature relies on the new v5 on-disk format that has been considered stable for production workloads starting Linux Kernel 3.15. It does not change existing on-disk structures, but adds a new one that must remain consistent with the inode allocation btree; for this reason older kernels will only be able to mount read-only filesystems with the free inode btree feature.
The feature enabled by default when using xfsprogs 3.2.3 or later. If you need writable filesystem for older kernel, it can be disable with
finobt=0 switch when formatting a XFS partition. You will need
# mkfs.xfs -m crc=0,finobt=0 /dev/target_partition
or shortly (
# mkfs.xfs -m crc=0 /dev/target_partition
External XFS Journal
To reserve an external journal with a specified size when you create an XFS file system, specify the
-l logdev=device,size=size option to the
mkfs.xfs command. If you omit the
size parameter, a journal size based on the size of the file system is used. To mount the XFS file system so that it uses the external journal, specify the
-o logdev=device option to the mount command.
Root file system quota
XFS quota mount options (
prjquota, etc.) fail during re-mount of the file system. To enable quota for root file system, the mount option must be passed to initramfs as a kernel parameter
rootflags=. Subsequently, it should not be listed among mount options in
/etc/fstab for the root (
xfs_scrub_all fails if user "nobody" can not access the mountpoint
xfs_scrub_all, it will launch
xfs_scrub@.service for each mounted XFS file system. The service is run as user
nobody, so if
nobody can not navigate to the directory, it will fail with the error:
firstname.lastname@example.org: Changing to the requested working directory failed: Permission denied email@example.com: Failed at step CHDIR spawning /usr/bin/xfs_scrub: Permission denied firstname.lastname@example.org: Main process exited, code=exited, status=200/CHDIR
To allow the service to run, change the permissions of the mountpoint so that user
nobody has execute permissions.