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10 Reasons Why ZFS Rocks

Dec 01, 2009, 10:32 (0 Talkback[s])
(Other stories by Paul Rubens)

[ Thanks to Paul Shread for this link. ]

"1. Checksums in Metadata for Data Integrity

"Data integrity is of paramount importance in ZFS, and is the driver for many ZFS features.

"The file system uses a 256-bit checksum, which is stored as metadata separate from the data it relates to, when it writes information to disk. Unlike a simple disk block checksum, this can detect phantom writes, misdirected reads and writes, DMA parity errors, driver bugs and accidental overwrites as well as traditional "bit rot."

"2. Copy on Write

"ZFS ensures that data is always consistent on the disk using a number of techniques, including copy-on-write. What this means is that when data is changed it is not overwritten â€" it is always written to a new block and checksummed before pointers to the data are changed. The old data may be retained, creating snapshots of the file system through time as changes are made. File writes using ZFS are transactional â€" either everything or nothing is written to disk.

"3. Data Snapshots With Time Slider

"The latest version of OpenSolaris illustrates the power for ZFS's snapshot capability with a small graphical application called TimeSlider. ZFS can be configured to take a snapshot of the file system (or a section of it, such as just a user's home folder) on a regular basis â€" every 15 minutes, or every hour, and so on. These snapshots are very small and efficient, as only the deltas from the previous snapshot are stored."

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