Ext4 file system mount parameter Translation

Mount Option to ext4:

Ext4 file system is an advanced ext3 file system, which includes scalability and reliability.
Supports enhancements to large file systems.

Options: journal_dev, noload, Data, commit, Orlov, oldalloc, [No] user_xattr [No] ACL, bsddf, minixdf, debug, errors,
Data_err, grpid, bsdgroups, nogrpid sysvgroups, resgid, resuid, Sb, quota, noquota, kgquota, usrquota, [No] BH

Backward compatible with ext3 or ext2.

Journal_checksum
Enable checksum and magazine transactions. This will allow e2fsck recovery and kernel code
Corruption detected in the kernel. This is a compatible change and earlier versions of the kernel will be ignored.

Journal_async_commit
The submitted block can be written to the disk descriptor block without waiting. If an earlier version of kernel is enabled, it cannot be installed.
Device. This will enable

Journal = Update

The log of the ext4 file system is updated to the current format.

Barrier = 0/barrier = 1/barrier/nobarrier
This enables/disables the use of the jbd code write barrier. Barrier barrier = 1 = 0 disabled, enabled. This
You also need an IO stack that can support obstacles. If jbd gets an incorrect obstacle for writing, it will show
Warning again. Write barrier, execute the appropriate order on the disk for magazine submissions, volatility
The disk is written to the high-speed cache, which is safe to use and causes some performance loss. If your disk is powered in some way or by a battery
In addition, the disabled obstacles can safely improve performance. You can also mount the Options "barrier" and "nobarrier"
It can be used to enable or disable obstacles and is consistent with other ext4 mount options.

Ext4 file system. By default, it is difficult to write.

Inode_readahead = N
This adjustment parameter controls the maximum number of ext4 inode table pre-read algorithms for the node table blocks.
Rithm reads data into the buffer cache in advance. The default value is 32.

Stripe = N
Number of file system blocks. mballoc will try to use the allocated size and alignment. For RAID 5/6 Systems
This should be the number of file system blocks of the raid block size of the data disk.

Delalloc
Delay block allocation until the write time.

Nodelalloc
Disable latency allocation. When a block is allocated, user data is copied to the page cache.

Max_batch_time = microsecond
The maximum ext4 time to wait for other file system operations, is a batch with syn-
Asynchronous write operations. Because synchronous write operations will be forcibly submitted, and then wait
I/O is complete, it does not need to spend a lot of money, it can be a huge throughput victory, we wait for time, see there is a small amount
If it can be written synchronously with any other transactions. This algorithm is designed as automatic
The speed of the music disk, measured by the amount of time (average), it needs to complete the offense
Transaction. At this time, call "submission time ". If transactoin has been run for less
When you submit the job, you can view the submission time of the test sleep of ext4 to see if other operations will be added to the transaction.
The maximum submission time is max_batch_time. The default value is 15000us (15 ms ). This optimization can
Set max_batch_time 0 when you close it completely.

Min_batch_time = microsecond
The submission time set by this parameter (as described above) is even less than min_batch_time. It defaults to zero.
Microseconds. Increasing this parameter can increase the throughput of multiple threads and synchronize the workload.
Very fast disks increase latency at costs.

Journal_ioprio = PRIO
The submitted I/O priority (from 0 to 7, where 0 is the highest prerequisite) and can be used for I/O operations.
Kjournald2 is submitting an operation. This will be 3 by default, which is a slightly higher priority
Default I/O priority.

Abort

Call ext4_abort () for debugging purposes. This is usually used to reload
The file system that has been installed.

Auto_da_alloc | noauto_da_alloc
Many broken applications do not use fsync () When noauto_da_alloc replaces the existing mode, such

FD = open ("foo. New")/write (FD,...)/close (FD)/Rename ("foo. New", "rich ")

Or worse

FD = open ("rich", o_trunc)/write (FD,...)/close (FD ).

If auto_da_alloc is enabled, ext4 will detect replacement by renaming and replacement by truncation mode and force
Any delayed allocation block is allocated so that the next log is submitted.
In data = ordered mode, the data block of the new file is forced to rename () before the operation is submitted to the disk.
This provides roughly the same level to ensure that the value is ext3, which avoids the "zero length" problem and may occur.
When the system crashes, it is forced to delay the allocation of block disks.

Discard/nodiscard
When the underlying block device/trim command block that should be discarded is released ,.
SSD devices and sparse/automatically streamlined Lun configurations are very useful, but it is disabled by default until there is enough
The test has been completed.

Nouid32
Disable the 32-bit UID and GID. This is in the old kernel, storage and expected interoperability
16-bit value.

Adjust the size of the last existing block group at the end of the file system that allows you to resize. You must make further adjustments.
Whether online or offline. It can be used only in combination with reload.

Block_validity/noblock_validity
This option enables/disables devices in the kernel and is used to track the metadata blocks in the file system.
Internal data structure. This allows you to quickly locate multiple distributors and other programs.
Metadata blocks of the file system may overlap. This option is used for debugging because it is negative
Tively affects performance, which is disabled by default.

Dioread_lock/dioread_nolock
Controls whether to use Dio read lock for ext4. If the ext4 value specified by the dioread_nolock option is
The extent to which the allocation is not initialized is the degree to which the I/O initialization and conversion are completed after the buffer is written. This
This method allows ext4 code to avoid the use of inode mutex, thus improving the scalability of High-Speed memory. However
This is not feasible with the nobh option, and installation will fail. It works with data logs and
The dioread_nolock option is ignored and kernel warning is triggered. Note that the dioread_nolock code path is only used
Disk-based files. This option is disabled by default (for example, dioread_lock ).

I _version
Enable support for the 64-bit inode version. This option is disabled by default.