Was studying the XFS filesyetsm to understand . Come through some good and easily understandable docs. below are the extracts .'.......................
The XFS file system was developed as a journaling file system that uses a B-tree balanced tree algorithm to allocate data as fast as possible.
One of the major design goals was support for large files and large file systems. The maximum file size currently supported is 2 Exabytes,
and the maximum file system size is 8 Exabytes.
The direct I/O option guarantees that a file is not buffered in buffer cache, but written to disk immediately after it has been committed.
XFS exclusively offers a guaranteed rate I/O, which guarantees that certain file systems have a minimum I/O-bandwidth.
Features of XFS Filesystem
1. Journaling
journaling is a capability which ensures consistency of data in the file system, despite any power outages or system crash that may occur. XFS provides journaling for file system metadata,
where file system updates are first written to a serial journal before the actual disk blocks are updated.
2.Allocation Groups
XFS file systems are internally partitioned into allocation groups, which are equally sized linear regions within the file system. Files and directories can span allocation groups. Each allocation group manages its own inodes and free space separately,
providing scalability and parallelism so multiple threads and processes can perform I/O operations on the same file system simultaneously.
3.Stripped allocation
If an XFS file system is to be created on a striped RAID array, a stripe unit can be specified when the file system is created. This maximizes throughput by ensuring that data allocations,
inode allocations and the internal log (the journal) are aligned with the stripe unit.
Variable block sizes
When many small files are expected, a small block size would typically maximize capacity, but for a system dealing mainly with large files,
a larger block size can provide a performance efficiency advantage.
Delayed allocation
When a file is written to the buffer cache, rather than allocating extents for the data, XFS simply reserves the appropriate number of file system blocks for the data held in memory. The actual block allocation occurs only when the data is finally flushed to disk.
This improves the chance that the file will be written in a contiguous group of blocks, reducing fragmentation problems and increasing performance.
Direct I/O
For applications requiring high throughput to disk, XFS provides a direct I/O implementation that allows non-cached I/O operations to be applied directly to the userspace. Data is transferred between the buffer of the application and the disk using DMA,
which allows access to the full I/O bandwidth of the underlying disk devices.
The XFS file system was developed as a journaling file system that uses a B-tree balanced tree algorithm to allocate data as fast as possible.
One of the major design goals was support for large files and large file systems. The maximum file size currently supported is 2 Exabytes,
and the maximum file system size is 8 Exabytes.
The direct I/O option guarantees that a file is not buffered in buffer cache, but written to disk immediately after it has been committed.
XFS exclusively offers a guaranteed rate I/O, which guarantees that certain file systems have a minimum I/O-bandwidth.
Features of XFS Filesystem
1. Journaling
journaling is a capability which ensures consistency of data in the file system, despite any power outages or system crash that may occur. XFS provides journaling for file system metadata,
where file system updates are first written to a serial journal before the actual disk blocks are updated.
2.Allocation Groups
XFS file systems are internally partitioned into allocation groups, which are equally sized linear regions within the file system. Files and directories can span allocation groups. Each allocation group manages its own inodes and free space separately,
providing scalability and parallelism so multiple threads and processes can perform I/O operations on the same file system simultaneously.
3.Stripped allocation
If an XFS file system is to be created on a striped RAID array, a stripe unit can be specified when the file system is created. This maximizes throughput by ensuring that data allocations,
inode allocations and the internal log (the journal) are aligned with the stripe unit.
Variable block sizes
When many small files are expected, a small block size would typically maximize capacity, but for a system dealing mainly with large files,
a larger block size can provide a performance efficiency advantage.
Delayed allocation
When a file is written to the buffer cache, rather than allocating extents for the data, XFS simply reserves the appropriate number of file system blocks for the data held in memory. The actual block allocation occurs only when the data is finally flushed to disk.
This improves the chance that the file will be written in a contiguous group of blocks, reducing fragmentation problems and increasing performance.
Direct I/O
For applications requiring high throughput to disk, XFS provides a direct I/O implementation that allows non-cached I/O operations to be applied directly to the userspace. Data is transferred between the buffer of the application and the disk using DMA,
which allows access to the full I/O bandwidth of the underlying disk devices.
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| time spent removing large files |
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| Comparison of b lock dev ice, XF S , ex t4, and ex t3 w h e n w r i t i n g large f i l e |
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