> Using a swap file on SSD will allow fine tuning I'm not sure this is a good idea. SSD bits degrade every time they are written. While modern SSD chips have a memory manager chip that is supposed to lock out failed bits, you still are degrading it when you write to it. And there's a LOT of writes to swap. For a desktop that you throw the SSD away when it fails because the user is supposed to be saving to the network, that might be one thing but I wouldn't do it if you don't have a server and are saving everything to your desktop.
With the price of ram just fill it up and if the system -insists- on creating a swapfile, then create a ramdisk and swap to that. Ted -----Original Message----- From: PLUG <[email protected]> On Behalf Of Michael Ewan Sent: Saturday, July 29, 2023 9:08 AM To: Portland Linux/Unix Group <[email protected]> Subject: Re: [PLUG] SSD swap partition and/or swap file There is a difference between swap and paging, but both use the "swap" space. Modern memory management and cheap ram have mostly done away with swapping however paging happens all the time. The best thing to do is install sar if not already installed via 'apt-get install sysstat'. Sar will give you paging stats, start the service and check the results after a few hours of normal operation with 'sar -B' and 'sar -S'. Bottom line, swap is very bad, some small amount of paging is normal when there is not enough RAM for everything that is running on the system. Back when I was running large UNIX (not Linux) hosts for MRP applications, we sized the the system RAM so there was never page outs, the same could be accomplished for a largish Linux box. Using sar you can gauge how much paging space you will need. Most estimates you will find in the literature will be way too large. Using a swap file on SSD will allow fine tuning. With enough RAM you would not need swap space at all, but you should configure some small amount to avoid crashes. On Fri, Jul 28, 2023 at 4:05 PM Keith Lofstrom <[email protected]> wrote: > Question about swap file vs swap partition. > > I have a dozen spinny disks with too many ancient distros on too many > machines. > > I am slowly consolidating to a few Debian 12 Bookworm machines with > Samsung terabyte SSDs. > > > When large-RAM low-power fast motherboards become cheap enough, I will > migrate to those. More RAM may imply larger swap areas (a > semi-religious debate I hope to avoid). I want to be ready if the > "large swap" zealots win the debate and design software dependent on > swap. > > SSD swap seems MUCH better than spinny-disk swap, very fast access > compared to moving a spinny disk head across a platter ... though way > slower than RAM. > > ---- > > Large SSD swap also facilitates fast hibernate, though Debian startup > and shutdown are amazingly fast using an SSD (10 seconds > startup/login, 2 second shutdown). > > Perhaps I don't need hibernate-to-swap. > > ---- > > One of my recent SSD experiments resulted in a too-small swap > partition. Inept resizing attempts borked the file system. > > But ... I can also create a huge swap file on a regular > ext4 file system, and easily up-size the swap file when I install more > RAM. Resizing a partition is more complex. > > I've read some online debates about swap partitions vs. > swap files. Most of the debates are from the spinny disk era; the > speed tradeoffs have changed radically. > My main concern is reliability, software compatibility, and ease of > maintenance rather than maximum speed. > > ---- > > I suspect I will need SOME separate-partition swap, but I hope I can > get by with a few gigabytes, relying mostly on a big swap file, > growing that swap file over time as I migrate to motherboards and > laptops with more RAM. > > At 69.9 years of age, I should also minimize complexity, deploying > systems that I can maintain with an 80 or 90 y.o. brain someday. My > father-in-law is 105, and his Windoze computer took many days to > decrapify. I won't have a son-in-law to do that for me. > > So, that's a lot of yammering, another sequela of excess age. In > summary: > > "Optimum SSD swap? ?? ???" > > Keith > > -- > Keith Lofstrom [email protected] >
