3 ms·

I was thinking that the controller probably takes care of interleaving data across platters, so at least small enough random I/Os would be able to use only one

I was thinking that the controller probably takes care of interleaving data across platters, so at least small enough random I/Os would be able to use only one actuator. I did some more reading and the PDF [1] says it shows up as two separate LUNs behind a single SAS port, but sharing the drive cache. But what I initially didn't catch (and another comment here pointed out), is how come they claim to do over 500 MB/s of sequential scanning I/O. Small random IOPS I get, but for large sequential I/Os you still have the same amount of platters, with the same bit-density, rotating at the same speed... Or is even the sequential I/O throughput "bottleneck" mostly dominated by the tiny seeks + calibration to the next adjacent track and not the actual magnetic reading part? I now really want to buy one for (some?) reason. Could get an used version from amazon for $150 but I'll try to hold back. It's also interesting that there are no new, unused versions available there (discontinued?) [1] https://www.seagate.com/files/www-content/solutions/mach-2-multi-actuator-hard-drive/files/tp714-dot-2-2006us-mach-2-technology-paper.pdf https://www.seagate.com/files/www-content/solutions/mach-2-m...

ssl-3 2y ago
Transfer rates can be doubled by spreading (something like) RAID 0 across those two LUNs, if doubling transfer rate and treating it all as one logical device is the goal. The drive doesn't know how to do this by itself. (That doesn't mean that the marketing wank is a lie: It's still a singular drive with a singular SKU. The marketing wank may easily be considered to be incomplete, however.) These drives have been available for a fair time now, though they're still fairly new. They were never intended for plebs like us to be able to buy from places like Amazon, probably because the support costs would be through the roof for such an unusual product with such niche use-cases.

ssl-3 2y ago

Transfer rates can be doubled by spreading (something like) RAID 0 across those two LUNs, if doubling transfer rate and treating it all as one logical device is the goal. The drive doesn't know how to do this by itself. (That doesn't mean that the marketing wank is a lie: It's still a singular drive with a singular SKU. The marketing wank may easily be considered to be incomplete, however.) These drives have been available for a fair time now, though they're still fairly new. They were never intended for plebs like us to be able to buy from places like Amazon, probably because the support costs would be through the roof for such an unusual product with such niche use-cases.