Ars Technica reports today on Windows Home Server, built on Windows Server 2003. While most people will just use it as a glorified fileserver (indeed, if anyone gets one at all; they’re not offering an OEM version, and do-it-yourselfers automatically seem like the biggest audience for this kind of thing, but apparently not in MS world), I think my favorite part was where they touted one of their “brand new” technologies:
In terms of storage for files, music, etc., users of the WHS won’t see a “C:\” drive, but instead just a single storage pool which can be almost endlessly expanded thanks to WHS Drive Extender. This is accomplished with a new twist on dynamic disk control. Adding more space will be as simple as adding more hard drives (internal or external, ATA/SATA or USB/Firewire) and using a tool to add that drive’s capacity to the central store. The use of dynamic disks will also allow for a degree of data redundancy. This isn’t RAID, but something more akin to data mirroring.
Now, where have I heard this before… oh right, Sun already did it.
Unlike a traditional file system, which resides on a single device and thus requires a volume manager to use more than one device, ZFS is built on top of virtual storage pools called zpools. A pool is constructed from virtual devices (vdevs), each of which is either a raw device, a mirror (RAID 1) of one or more devices, or a RAID-Z group of two or more devices. The storage capacity of all vdevs are then available to all of the file systems in the zpool.
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Dynamic striping across all devices to maximize throughput means that as additional devices are added to the zpool, the stripe width automatically expands to include them, thus all disks in a pool are used, which balances the write load across them.
There’s no wheel so awesome as the one you reinvent.