Wandering Thoughts archives


Using NVMe SSDs over SATA SSDs in basic servers is an awkward sales pitch

We have traditionally mostly bought basic, inexpensive 1U servers, almost all of which have had either two or four drive bays. Our transition of these servers from using HDs to using SATA SSDs was relatively straightforward. It was driven by dropping SATA SSD prices, the clear improvements in performance even for casual activities like installing the operating system and upgrading packages (and rebuilding software RAID mirrors), the probable increase in service lifetime, and how relatively easy it was to substitute a SATA SSD for a SATA HD (except that for a while that was a hassle, which slowed down our transition).

Putting NVMe SSDs in such basic servers with only a few drive bays is reasonably doable in terms of PCIe lanes and space. Even if you support four NVMe SSDs, that only needs 16 PCIe lanes, the M.2 form factor doesn't need much space, and people have accepted non-hotswap drives in 1U servers before (our Dell R210s have two non-hotswap bays). Or you could go with the U.2 NVMe form factor; as noted by Andy Smith in a comment on my entry on SSD versus NVMe for basic servers today, Tyan will already sell you a 1U server with 4x U.2 and 4x 3.5" drive bays (here's one model).

However, actually getting people to do this seems like an awkward sales pitch. Right now you'd either pay more for a U.2 SSD or probably live without hotswap for an M.2 NVMe SSD, and while you get much better IO performance, relatively few basic 1U servers are doing things that are IO constrained on SATA SSDs. If you're using SATA SSDs, you're getting the durability advantages of solid state storage and probably most of the power and heat savings, and you've already taken the first massive leap from HD performance.

What feels to me the most likely path toward NVMe on basic servers is the spread of machines like Tyan's model, with 4x U.2 and 4x 3.5" bays (at competitive prices against basic 1U servers if the U.2 bays are empty). We and probably many other buyers would almost always use SATA SSDs in the 3.5" bays, but if U.2 SSDs became competitively priced we would probably start switching to them (if nothing else, we wouldn't need adapters). The existence of these servers with the option of U.2 might act to drive down the price of U.2 SSDs by increasing the market (we can hope).

(Having the option of either 3.5" bays or NVMe bays seems smart, because HDs remain your best option if you want a lot of disk space in not much physical space or cost. You can now get 4 TB SATA SSDs, but they're quite costly. Meanwhile, 8 TB HDs are a few hundred dollars.)

Another option is that makers of basic servers could make very short servers that use M.2 NVMe SSDs on the motherboard in order to save internal space. Dell already did something like this with their half-length R210s, which had non-hotswap drive bays because the drives were mounted sideways to save depth. However I'm not sure how much of a priority rack depth is for people these days and we certainly found that having a mix of rack depths could be awkward. If these servers were the inexpensive option, we would probably buy some (assuming M.2 NVMe SSD prices for small sizes stay basically the same as the same sized SATA SSDs).

All of this leaves me expecting that any transition of basic servers to NVMe for us will be every slower than our transition to SATA SSDs, which took way more time that I expected (we more or less started in 2013 but as late as 2017 we were still using HDs in some new servers).

tech/ServerNVMEHardSalesPitch written at 23:25:34; Add Comment

My view of Wayland here in 2021

Somewhat recently there was some Wayland related commotion in the Unix tech circles that I vaguely follow, where Wayland people were unhappy about what anti-Wayland people are doing (for example, which may have been reacting to this). Somewhat in reaction to all of this, I had a Twitter reaction:

My Wayland hot take is that I have no idea how well Wayland works in general, but I do know that for me, switching to it will be very disruptive because I'll need a new window manager and none of the Wayland ones work like my fvwm setup does. So I am and will be clinging to X.

I can't say anything about what modern Wayland is like, because I have no personal experience with Wayland. On my work laptop I use Cinnamon, which doesn't support Wayland. On my home and work desktops, I use a highly customized X environment that would not port to Wayland.

At this point Wayland has been coming for more than ten years and has nominally been definitely the future of Unix graphics for four years. But it's fully supported on all Linux graphics hardware by only two environments (GNOME and KDE, see Debian's description of the hardware requirements). Only two of the five significant Linux desktop environments support Wayland on any hardware (GNOME and KDE, with Cinnamon, XFCE, and MATE not). Canonical is only just releasing a version of Ubuntu that uses Wayland for GNOME by default (21.04), and even then it may not do this on Nvidia GPUs (cf). There are some additional Wayland 'window managers' (compositors) such as Sway, but nothing like the diversity that exists on X (although there may be good reasons for this).

Today, it's not so much that people are refusing to use Wayland, it's that a lot of people cannot. If you're not using GNOME or KDE, you're pretty much out in the cold. If you're using an Nvidia GPU, you're probably out in the cold (even if you use GNOME, your Linux probably defaults to Xorg on your hardware). If you don't use Linux, you're definitely out in the cold.

It's true that X server development has more or less stopped (eg, also), although the X server 21.1 milestone seems small right now. It's also true that the current X server works and supports a broad range of desktop environments and Unixes, and plenty of people are using those.

PS: I don't like Nvidia GPUs either and I don't use them, but a lot of Unix people have them and some of those people don't have any choice, for example on some laptops (or people who need to do GPU computation). And they work in X.

Sidebar: Some Wayland references

See the Debian wiki page on supported and unsupported desktop environments, toolkits, and so on. Debian has been using Wayland for GNOME since Debian 10, released in 2019, at least on non-Nvidia hardware. Their Wayland and Nvidia wiki pages are unclear if their GNOME defaults to Wayland even on Nvidia hardware, but I suspect not. The Arch wiki has a list of Wayland compositors, but no information on how usable they are. The Gentoo "Wayland Desktop Landscape" may be helpful, especially since it rates some of the available compositors.

unix/WaylandMyView2021 written at 00:28:02; Add Comment

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