31-05-2011, 09:50 AM
SYNOPSIS
NAME: ZFS FILE SYSTEM
AREA: FILE SYSTEM
ORIGIN:
FS was designed and implemented by a team at Sun led by Jeff Bonwick. It was announced on September 14, 2004.[4] Source code for ZFS was integrated into the main trunk of Solaris development on October 31, 2005[5] and released as part of build 27 of OpenSolaris on November 16, 2005. Sun announced that ZFS was included in the 6/06 update to Solaris 10 in June 2006, one year after the opening of the OpenSolaris community.[6]
The name originally stood for "Zettabyte File System". The original name selectors happened to like the name, and a ZFS file system has the ability to store 258 zettabytes, where each ZB is 270 bytes.[7]
ABSTRACT:
ZFS is a revolutionary file system developed by Sun Microsystems and open source community developers. It leverages the best features found in other products found currently on the market, such as network appliances snapshots, object-based storage management, transaction and checksumming, deduplication, with own ideas. The end result is a completely new approach to file system design. ZFS is very young, yet it made such an impact on Unix vendors and open source community that many have planned and already ported ZFS to other operating systems.
ZFS addresses may issues of modern file systems. File integrity, scalability and management difficulties are all thing of the past with the use of ZFS.
Storage Pools
ZFS eliminates the need for volume manager. Instead of create virtual volumes, devices are grouped in storage pools. That leads to system without individual physical devices, that allows to share entire disk space with all file systems in pool. When a new devices are added to the storage pool, all file systems can allocate additional space. It resembles virtual memory operation. When additional memory banks are added to the system, the operating system does not force user to configure additional memory, all processes in the system can automatically use additional memory.
FEATURES:
Data Integrity
One major feature that distinguishes ZFS from other file systems is that ZFS is designed from the ground up with a focus on data integrity. That is, protect the user's data on disk, against silent corruption caused by e.g., bit rot, cosmic radiation, current spikes, bugs in disk firmware, ghost writes, etc
Capacity
ZFS is a 128-bit file system, so it can address 1.84 × 1019 times more data than 64-bit systems such as NTFS[citation needed]. The limitations of ZFS are designed to be so large that they would never be encountered.
Copy-on-write transactional model
ZFS uses a copy-on-write transactional object model. All block pointers within the filesystem contain a 32-bit checksum or 256-bit hash (currently a choice between Fletcher-2, Fletcher-4, or SHA-256)[25] of the target block which is verified when the block is READ
Snapshots and clones
An advantage of copy-on-write is that when ZFS writes new data, the blocks containing the old data can be retained, allowing a snapshot version of the file system to be maintained. ZFS snapshots are created very quickly, since all the data composing the snapshot is already stored; they are also space efficient, since any unchanged data is shared among the file system and its snapshots.
ZFS has a pipelined I/O engine, similar in concept to CPU pipelines. The pipeline operates on I/O dependency graphs and provides scoreboarding, priority, deadline scheduling, out-of-order issue and I/O aggregation. I/O loads that bring other file systems to their knees are handled with ease by the ZFS I/O pipeline.
APPLICATION:
ZFS provides built-in compression. In addition to reducing space usage by 2-3x, compression also reduces the amount of I/O by 2-3x. For this reason, enabling compression actually makes some workloads go faster.
In addition to file systems, ZFS storage pools can provide volumes for applications that need raw-device semantics. ZFS volumes can be used as swap devices, for example. And if you enable compression on a swap volume, you now have compressed virtual memory.
ZFS administration is both simple and powerful. Please see the zpool(1M) and zfs(1M) man pages for more information — and be sure to check out the Getting Started section for a whirlwind tour.
