Anssi Saari wrote: > > Yes. Also not many drives can sustain a multi-gigabyte write rate > > anyway... > > I have to say I was quite disappointed when I cloned a 1TB SSD to a 2TB > one, average speed wasn't much higher than writing to an HD. I don't > remember what the target drive was though. Since I don't intend to make > a habit of this, no big deal, but I wonder what kind of write speed one > could expect in a sustained write of 1TB?
One of the tests that servethehome.com does in reviewing SSDs is the write speed after cache saturation: that is, once you have sent enough gigabytes in a row, what is the ongoing write speed? It is not unusual for a PCIe NVMe device to manage writing the first few gigabytes at 4000 MB/s... and then drop to 500, 200 or even 150 MB/s for the long haul. And for many workloads, that's completely reasonable. It doesn't help all that much for copying large filesystems. Note that spinning disks have improved transfer speeds in the last few years. 100-120 MB/s was all you could expect for more than a decade, but you can now find disks that will do 180-250 MB/s for large contiguous transfers. -dsr-
