DEBRIS.COMgood for a laugh, or possibly an aneurysm

I needed a benchmark to determine just how fast my striped SCSI RAID subsystem really was. I found xbench.

First I tested my local applications partition, expecting serious fireworks. But the results were underwhelming; for a pair of drives that are each capable (theoretically) of delivering 80 Mb/sec, this was pitiful:

Sequential
  Uncached Write    0.63 MB/sec [4K blocks]
  Uncached Write   22.27 MB/sec [256K blocks]
  Uncached Read     9.05 MB/sec [4K blocks]
  Uncached Read	   23.92 MB/sec [256K blocks]
Random
  Uncached Write    0.86 MB/sec [4K blocks]
  Uncached Write   13.16 MB/sec [256K blocks]
  Uncached Read	    0.45 MB/sec [4K blocks]
  Uncached Read	   12.52 MB/sec [256K blocks]

Next I tested the stock boot drive in the new G5:

Sequential
  Uncached Write   33.66 MB/sec [4K blocks]
  Uncached Write   44.66 MB/sec [256K blocks]
  Uncached Read    31.85 MB/sec [4K blocks]
  Uncached Read    53.29 MB/sec [256K blocks]
Random
  Uncached Write    1.82 MB/sec [4K blocks]
  Uncached Write   34.45 MB/sec [256K blocks]
  Uncached Read	    0.64 MB/sec [4K blocks]
  Uncached Read	   24.92 MB/sec [256K blocks]

Well, OK then. No wonder Apple used SATA.

I still needed a RAID solution for data safety — RAID-1, mirroring, writes every file to N separate devices. In this case N=1, because that’s all the room there is in the case.

Adding a second SATA drive to the G5 took 5 minutes. Apple provides the screws and cables. Like everything else about the physical layout of the G5, the drive bays deserve a feature in Architectural Digest.

Initializing the drive with SoftRAID took a few more seconds. And then I used SoftRAID’s “convert to mirror” feature to turn the original boot drive into a RAID-1 array. This took all night, as every byte (even the free space) was copied to the new drive and verified.

Ironically, my xbench scores dropped after this operation. So much for improving performance via striped reads.

Even so, overall the SATA RAID still a whole lot faster than my current setup — conservatively, it’s twice as fast by most measures, and subjectively about five times as fast. It’s also simpler because there’s no aftermarket SCSI interface, no 3rd-party driver software, no additional cables, no terminator hijinks. And it’s quieter, both because modern drives are less noisy than vintage components, and because I have only two of them, rather than three.