Ubuntu's Swap file = "dangerous"

mcburks

In section 17 regarding disk partitions it states:

"Some distributions, such as Ubuntu, default to a swap file rather than a partition. While this approach is more flexible, it is also more dangerous if error or bug occurs."

Could I get a bit more info on how that makes it more flexible as well as why it would make it more dangerous?

Thanks,
Matt

coop

It is more flexible because you don't have to dedicate a partition to swap and can more easily resize it as needed (you can always add more swap space as files or partitions, but shrinking the partition is more painful). It is (perhaps) more dangerous, however, if it is on the same partition as the rest of your data and files and if you have corruption in either the swap or the rest of the partition it can get destructive. Another reason applicable to older rotational non-SSD disks is that the blocks in the swap file can get fragmented and slow performance.

However, personally, I think there is no good reason to demand a swap partition any more and I have generally gone over to using swap files. Probably this will be reworded in the next update, and I thank you for your raising this issue. Unless there is a good reason for it I don't use a lot of partitions any more, mainly doing it to put non-volatile data on slower and cheaper rotational media, and things used all the time on fast SSD type media.

mcburks

That makes sense. Thanks for answering my question. Was need to no longer use a swap partition mainly a direct result in the industry moving over to SSDs?

Also, in my cloud lab setup all of my servers are using NVME drives so I'm seeing /dev/nvme0 and /dev/nvme0n1 as well as /dev/nvme0n1p[1-3]. Do these essentially work just like a /dev/sda[#] would or do they have any other special attributes? (this should perhaps be a separate question)

coop

Industry has not made some wholesale move, most Enterprise distributions will still ask you to set up a swap partition during install, although Ubuntu does not and I'm not sure but I don't think Fedora does.

On your second questions, everywhere you see something like /dev/sdayou can substitute /dev/nvme0n1 etc, except the name convention is a little different as you note; i.e., /dev/sda2 is like /dev/nvme0n1p2 (the p seems additional, I have no idea why)