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1. Introduction
ceph bluestore tmpfs file system is mounted, so learning under tmpfs file system; This article describes the basic concept tmpfs file system
2, tmpfs basics
2.1 tmpfs introduce
tmpfs (temporary filesystem) is Linux-specific file system
- Standard mount point is / dev / shm (also can be customized)
- The default size is half of the actual memory
- tmpfs is a separate file system, not a block device, as long as the mount, can be used immediately
# free -h
total used free shared buff/cache available
Mem: 31G 8.5G 22G 33M 654M 22G
Swap: 15G 4.0M 15G
# df -h
Filesystem Size Used Avail Use% Mounted on
tmpfs 16G 24K 16G 1% /var/lib/ceph/osd/ceph-4
tmpfs 16G 24K 16G 1% /var/lib/ceph/osd/ceph-2
tmpfs 16G 24K 16G 1% /var/lib/ceph/osd/ceph-0
... ...
2.2 tmpfs features
temporary: Since tmpfs is built in memory, all the data stored in tmpfs in the power outage will be lost after unloading or
fast reading and writing skills: memory access speed is much faster than disk I / O operations, even if use the swap, the performance is still unsurpassed
dynamic contraction: tmpfs started with a very small space, but with the copy and create files, tmpfs file system will allocate more memory, and in accordance with the needs of dynamically increases the file system space; and when tmpfs files are deleted, tmpfs file system will dynamically reduce the file and free up memory resources
3, tmpfs mount
3.1 Mounting
3.1.1 Direct mount
# mount -t tmpfs -o size={size} tmpfs {mount_point}
3.1.2 Remount
# mount -t tmpfs -o remount tmpfs {mount_point}
3.2 boot from Kai
# cat /etc/fstab
# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point> <type> <options> <dump> <pass>
# /was on /dev/sda3 during installation
tmpfs /tmp tmpfs defaults,size=25M 0 0