On Tue, Jan 27, 2015 at 05:47:07PM -0700, Chris Murphy wrote: > On Tue, Jan 27, 2015 at 5:28 PM, "Jóhann B. Guðmundsson" > <johan...@gmail.com> wrote: > > > > On 01/28/2015 12:24 AM, Lennart Poettering wrote: > >> > >> On Tue, 27.01.15 17:17, Chris Murphy (li...@colorremedies.com) wrote: > >> > >>>> > >The problem is simply that we cannot know in advance that /dev/sda7 > >>>> > >and /dev/disk/by-uuid/c0e7978b-f82b-4b7f-b72b-6717f6909abc will > >>>> > >eventually refer to the same device. > >>> > >>> > > >>> >Are these just scary looking warnings? > >> > >> It should be unproblematic, but it looks scary right now. The swapon > >> will only succeed once, and fail the second time, and that doesn't > >> look pretty, but the kernel should do the right thing and not get > >> confused by this. > > > > > > I can confirm it does and I simply remove the swap entry in fstab to make it > > go away when I encountered it. > > > > That said are there any real practical benefits of using swap et al in > > today's age or are people just still creating it out of habit? > > For those who have hibernation working, it's needed. And there's a > case for it on baremetal servers, it's sometimes better that they slow > down instead of totally face planting. And it can be useful if you > don't have enough memory to do a full fsck on a large file system, > especially if swap is on an SSD it's not as slow as on a HDD. But > otherwise, maybe not. You also need swap if you want to use all of your memory. If you have no swap, allocating close to 100% RAM becomes very dangerous, because any overflow will result in oom. If you have swap configured, it acts as a safety valve. For example, I have servers with long-running simulations where the amount of memory used tailored to the task, and >95% of memory is used. If I logged into this machine and run the package manager, without swap, the kernel would start killing off the jobs.
Zbyszek > Over on that other OS that begins with W, it looks like they aren't > using swap directly. Instead there's a separate Intel Rapid Start > specific partition (it has it's own GPT partition type GUID) that puts > some kind of hibernation like file there on normal shutdown. Cold boot > times are insanely fast, like 3-4 seconds from pushing the button. _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
