NetBSD and SSDs

ajgraves

Hello all! After some consideration, I just ordered a ThinkPad X1 Carbon (2nd gen) off eBay, and expect it to arrive this week. My intention is to install NetBSD on it.

I haven't been able to turn up much info yet, but wanted to get some thoughts on if any special considerations need to be done to tune NetBSD to running on SSDs. My current primary machine is a ThinkPad T420 running Endeavour (Arch-based Linux distro) and I recall having to tune some things so it wouldn't aggressively wear out the drive. Just trying to get a feel for if that's necessary on NetBSD or not.

I also have an old Lenovo Flex 3-1120 that I installed OpenBSD on last week. Aside from the fact that this particular hardware is very slow (also has a spinning hard drive), I've been impressed with OpenBSD so far in terms of it just working with very little tuning needed.

Thanks in advance!

ajgraves

Of course now that I post this, I just noticed in this thread there's a suggestion for mount options on an SSD. Still would love to hear if there's any more thoughts.

nia

The minimum mount options I would enable in fstab are noatime,nodevmtime. These decrease the number of metadata updates to files, helping preserve the flash and reducing power consumption on a laptop. Log and discard have their benefits and drawbacks, the discard implementation could do with being replaced by something better. Log enables journalling for metadata but not file contents, speeding up fsck. FFS has a notable long-term flaw where garbage can be appended to open files in the event of an unclean shutdown, and it's much more noticeable with log enabled (probably because updates happen more frequently). Of course these days you can keep important data in a ZFS partition...

ajgraves

nia Thanks for that information! I'm not entirely sure I'll use ZFS, I suppose I should give that some consideration before going through the install.

JuvenalUrbino

nia The minimum mount options I would enable in fstab are noatime,nodevmtime.

I wrongly presumed noatime to be a default on amd64 but this wouldn't have made sense indeed.Looks like I didn't recall having set it my laptop. Well, it's been a long time since I last did a NetBSD installation.
I had never heard of nodevmtime , so thanks for pointing that out. I'm curious to see how will this impact my battery life.
As a side note, thanks god there's somebody knowledgeable turning a blind eye on the nonsense I come up with 😉

neubaer

nia From what I've seen, SSD manufacturers prefer a weekly scheduled trim/discard of all unused blocks at once. That seems a bit simpler than trying to immediately discard blocks as they are freed, considering the "reputation" for "quality" SSD firmwares have.

nia

JuvenalUrbino It's the default on ARM if you use the "live images", because most people will be flashing them to a SD card :-/