There's definitely a tradeoff.
My systems are all part of my grand adventures where I make different
choices than I would for a system used by others for community,
commercial or mission critical purposes.
Heck, I'd do it differently even if I were just maintaining a system for
my wife's use (she uses Windows for work and on-and-off tries to justify
a Mac for personal use, but never quite indulges).
On 2022-11-30 15:00, Derek Martin wrote:
On Fri, Nov 18, 2022 at 11:05:52AM -0800, Kent Borg wrote:
I put /tmp and /var/tmp in RAM disks, figuring that would move some
background activity off the SSD.
Rich already pointed out a potential downside of this... here are a
couple other points to consider, which you might not have:
- /tmp and /var/tmp have different intended use cases; /var/tmp is
meant for temporary files that should survive a reboot. They won't
on a ramdisk, so if you have applications using it properly, they
will be affected. What that means in practice will obviously
depend on the application...
- You never really know what applications are using /tmp or /var/tmp,
and how much storage they are using. An example from--wow, 21
years ago--when I was sysadmin at MCL (I'm going to assume my
memory is accurate despite the time frame, but offer the caveat
that it may not be):
The mail server (which was set up before they hired professional
sysadmins, for whatever that's worth) ran UW IMAP. The size of
/tmp was some small-but-seemingly-reasonable size--I don't remember
exactly but say 200MB or something like that (remember, 20+ years
ago). After a while people started to experience random failures
with their IMAP folders, and it took us some time to figure out
why... What actually was happening was that when you expunge
messages from your folder, the imap server was creating a temporary
copy of your folder in /tmp, and then copying it back to where it
was supposed to live. The filesystem was not sized appropriately
for that use case, and we ended up needing to make it much larger
to accommodate it.
Were I to have been the one to set up the server, I would've
allocated /tmp to be significantly larger than it was, but still
not likely large enough to accommodate this usage, having been
unaware of this at the time.
Point being, if you're running some application like this that
consumes much more temporary storage space than you anticipate, it
will exacerbate the issue Rich pointed out, and also increase the
likelihood you'll experience OOM situations causing your other apps
(or the same one) to crash randomly if you don't have enough RAM +
swap to cope.
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