The Intel Optane Memory H10 Review: QLC and Optane In One SSDby Billy Tallis on April 22, 2019 11:50 AM EST
This test starts with a freshly-erased drive and fills it with 128kB sequential writes at queue depth 32, recording the write speed for each 1GB segment. This test is not representative of any ordinary client/consumer usage pattern, but it does allow us to observe transitions in the drive's behavior as it fills up. This can allow us to estimate the size of any SLC write cache, and get a sense for how much performance remains on the rare occasions where real-world usage keeps writing data after filling the cache.
During a sustained write, the Optane cache on the Intel Optane Memory H10 doesn't change the situation much from how the QLC-only Intel 660p behaves—the Optane cache on its own is only good for about 350MB/s. The SLC write cache on the NAND side is a more important factor that helps sustain high write speed far beyond the 32GB size of the Optane cache. But eventually, all the caches fill up and the very slow write speed of raw QLC takes over.
|Average Throughput for last 16 GB||Overall Average Throughput|
The overall average write speed when completely filling the Optane Memory H10 is unsurprisingly lower than any of the other drives in this batch. The 1TB Intel 660p was already a bit slower than a 7200RPM hard drive, and our H10 sample has half as much QLC to work with.
Working Set Size
The Optane cache on the H10 is 32GB, but when testing random reads it appears to only be good for about 6-8GB working sets before the cache starts thrashing and performance drops down to roughly what a QLC-only drive can offer. It appears that Intel may be reserving a large portion of the Optane cache to serve as a write buffer, and this might be detrimental to the most read-intensive workloads.