Features[edit source | editbeta]
HAMMER file systems provide the following features:[5][6]
- configurable fine-grained and coarse-grained filesystem histories
- history and snapshots are accessible online
- near real-time log-less streaming mirroring to slaves or backups
- different retention parameters for slaves
- CRC checksumming of data and metadata
- no fsck required on remount
- 1 EiB maximum storage capacity
- online layout correction
- data deduplication, 一致数据去重的压缩技术
Limitations[edit source | editbeta]
Requires a pruning/reblocking cron job run a few minutes every night to incrementally clean up and regain space on the filesystem. Deletions do not immediately reclaim space.
Does not yet support multi-master configuration.
swapcache
SWAPCACHE - Managed SSD support
This DragonFly feature allows SSD-configured swap to also be used to cache clean filesystem data and meta-data. The feature is carefully managed to maximize the write endurance of the SSD. Swapcache is typically used to reduce or remove seek overheads related to managing filesystems with a large number of discrete inodes. DragonFly's swap subsystem also supports much larger than normal swap partitions. 32-bit systems support 32G of swap by default while 64-bit systems support up to 512G of swap by default.
http://www.dragonflybsd.org/docs/howtos/swapcache/
DragonFlyBSD的其他自主技术点
http://www.dragonflybsd.org/docs/developer/DragonFly_Technologies/
This page lists DragonFly inventions, new DragonFly tools, or DragonFly implementations of new technologies.
battd - Battery status monitoring daemon
checkpt - restore/resume support for Process Checkpointing (serialize process state to be resumed later on a compatible system)
devfs - dynamic device file system
diskinfo - report about block media devices
dma - The DragonFly Mail Agent
dntpd - Network time protocol client daemon
ECC detection - detects memory faults on supported systems
getdevpath - device label name and path mapping
HAMMER - file system for large and multiple volumes with historical data retention.
jscan - utility for scanning journaling files
mount_udf - mount a UDF file system
mountctl - control journaling and other features on mounted file systems
pctrack - dumps program counter tracking data recorded by the kernel
pkg_radd - allows installation of pkgsrc binaries, even if there isn’t a local pkgsrc tree
pkg_search - print information about a package
rconfig - Remote Configuration Client/Server
rcrun (and family) - for managing startup scripts (rcenable/rcdisable)
resident - make a dynamic binary memory-resident
syslink - connect pair of file descriptors between two processes
varsym - variant symlinks
vkernel - virtual kernel infrastructure allows the kernel to be run as a user-space process
vknetd - create virtualized bridged network suitable for vkernel use
wmake - build DragonFly source in a buildworld environment
