3 ms·
My interpretation is that it is a fancy cache using a new type of memory, XPoint, a non-volatile phase change memory, with greater endurance (and cost) than NAN
by 1001101 10y ago
My interpretation is that it is a fancy cache using a new type of memory, XPoint, a non-volatile phase change memory, with greater endurance (and cost) than NAND sitting on the M.2 bus, combined with OS drivers to assist with the mapping.
The idea is M.2 speed > SATA, but the dynamic M.2 caching isn't native to the OS, so drivers are required to intermediate.
Pretty underwhelming relative to the hype.
- dv_dt 10y agoM.2 is a hardware connector. It can carry various flavors of SATA or NVMe over PCIe lanes. Generally M.2 drives will be at least equal to a SATA drive on a traditional SATA connector, with the potential to be much faster. However, even some of the m.2/NVMe drives which are much faster at the bus level seem to be bottlenecked by some design assumptions (both inside the drive and above in the various OS layers). I think in the medium to longer term M.2/NVMe will be much faster. https://en.wikipedia.org/wiki/M.2 https://en.wikipedia.org/wiki/M.2
- sliken 10y agoJust buy a nicer M2 and you get plenty of performance without special drivers: # dd if=/dev/sdb of=/dev/null bs=131072 1953586+1 records in 1953586+1 records out 256060514304 bytes (256 GB, 238 GiB) copied, 159.18 s, 1.6 GB/s
- dv_dt 10y agoIf you don't test read with some writing, you might be misled by performance of an SSD. 100% read or 100% write are very different from 50/50 or even 70/30 r/w. The mixed bandwidth typically drops by a lot. If you haven't pre-written some data, that dd test might not even be touching the flash. Just reading internal metadata... But yes, nicer M.2s will perform better!