On Mon, May 20, 2019 at 11:42 AM D. Hugh Redelmeier via talk < [email protected]> wrote:
> | From: Russell Reiter via talk <[email protected]> > > | Optane was intended to be a cache memory to increase the performance of > | conventional spinning HD's under Windows OS. However, I've been booting > | Fedora from both a 500gb SSD and 32gb Optane Nvme as I tinker with my own > | desktop. > > I think Optane is just a brand name and that brand name gets attached > to several different things, some of which are not yet being sold. > True enough, sometimes it's hard to sort specifications from hyperbole. > > The original promise was: non-volatile memory that would get speed > close to RAM and price close to flash. (They also need better > durability than flash.) There's a big gap between those, and anything > in between ought to have a market. They just haven't been able to > accomplish much. > > - they wanted to produce things that fit in RAM sockets. That meant > either > > (1) no change from RAM interface (unlikely, but suggested-by-omission > in early marketing) or > > (2) memory interfaces that were augmented to support the new protocols > (delivered with some new Xeons, I think) > > - the NVMe stuff has had much worse durability than originally > promised. > > - the NVMe stuff has had quite small capacity compared with most SSDs > > - NVMe SSD has mostly been fast enough that the Optane stuff isn't > compellingly better > > | Most certainly booting to a login prompt is fractionally quicker > | on the Nvme than on the conventional SSD. > > That's what I'd expect. But I'll admit to no experience with Optane > and I haven't been following it closely. > > | However recently I up-sized my > | Nvme and have populated my M.2 slots with a 250gb WD black Nvme for boot > | and now added an additional 1TB to the second M.2 slot with F29 still on > | the SSD. Copying a 100gb image to the 1TB drive really hit performance > tho > > SSDs come with different performance trade-offs. Most inexpensive > SSDs have (on-board) controllers with only small amounts of RAM. This > makes them slow down a lot after a modest burst of intensive writing. > That's a fine trade-off for many of us but not for all workloads. > > You can pay more and get SSDs with enough RAM to not have this > performance problem. I don't know enough to give specific advice. > > I have recently learned that some cheap NVMe drives can ask the OS to > allocate system RAM for the exclusive use of the controller. This > isn't a conventional data cache, but something much stranger. It's > called "Host Memory Buffer" (HMB). I think that vendors don't explain > it because they think consumers won't understand it. > > HMB might be a great trade-off, or a horrible hack. I don't know. > What happens when the power fails? Or when the system crashes / > reboots? > > Recent Linux and Windows support HMB. I assume that UEFI firmware does > not. So use of HMB must be an optional speed-up. > > | and that was probably due to the lack of a decent heat sink. > | I just ordered a hteatsink fro the internal 1TB > > Why do you think that this was heat-related? It might be, but that > would not be my first guess. (I am not an expert on this.) > Apparently, at least on Crucial products, there is built in thermal monitoring which will throttle speeds. Here's a link to the 1TB Nvme. On sale for the next few days for $147.00, about $40.00 less than I paid. https://m.newegg.ca/crucial-p1-1tb/p/N82E16820156199?item=N82E16820156199&m_ver=1 Here's a link to a review of Crucial's Thermal Throttling capacities https://www.techpowerup.com/reviews/Crucial/P1_NVMe_M.2_SSD_1_TB/7.html > | Perhaps with the NUC form factor heat might > | be a problem on a larger sized Nvme but with USB-C you have wiggle room > for > | adaptation. > > The NUC form factor certainly reduces the heat disposal and thus > limits components. But the main such component is the CPU. I've not > heard of it being a problem for consumer 3.5" SSDs (what Evan intends > to use) or NVMe drives. > --- > Talk Mailing List > [email protected] > https://gtalug.org/mailman/listinfo/talk > -- Russell
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