Projects / Fast Intelligent Software RAID1

Fast Intelligent Software RAID1

This is a Linux kernel driver that adapts the kernel's own software RAID1 (i.e. mirroring) driver for use in the context of network attached storage. This driver tracks missed mirror updates on a faulted mirror component and when the component is repaired it updates only the missed blocks, not the whole device. This strategy is particularly suited to mirrors with remote components (see project ENBD), because faults are likely to be temporary, not catastrophic. Dis- and re-connects are noticed automatically and ensuing RAID administration is also handled automatically. Asynchronous writes cut latency to that of the fastest component. This driver is the first of several which will add network storage compatibility to the Linux kernels own software RAID drivers. It is compatible with the standard Linux raidtools2 software utilities package.

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Recent releases

  •  14 Apr 2003 17:18

    Release Notes: The driver now contains an experimental implementation of asynchronous mirrored writes, enabled with "async=1" at module load. Writes to a mirror are no longer twice as slow as normal. Old mirror components which are replaced into the array are now recognised automatically, and an intelligent resync of their not uptodate sectors alone is carried out. The driver cooperates with the ENBD (see freshmeat) driver in allowing it to advise automatically of its disabling or reenabling, and will initiate the appropriate reincorporation and resynchronization itself.

    •  11 Feb 2003 22:44

      Release Notes: The fast resync technology has been integrated into the existing kernel drivers. This code is now a patch to the existing md.c and raid1.c files in the 2.4 linux kernel. It is exactly as reliable as the existing kernel code, but with the extra functionality obtained when doing a hotadd after a setfaulty without an intervening hotremove. This combination signals a "hotrepair", which results in an intelligent and fast resync.

      •  24 Jan 2003 04:37

        No changes have been submitted for this release.

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