On Mon, Jan 8, 2024, at 14:41, Xin LI wrote: > > > On Sun, Jan 7, 2024 at 5:27 AM void <v...@f-m.fm> wrote: >> Hi, >> >> Does /var/mail still need atime? >> >> I've installed a ufs2-based -current main-n267425-aa1223ac3afc on >> rpi4/8BG which installs into one / . If it's mounted with noatime, >> will it have consequences for /var/mail ? > > It doesn't matter if you don't normally receive emails locally (nowadays, > it's rare). > > If you do receive emails locally, it depends on what application(s) that you > are using. Most applications nowadays check both mtime and atime plus sizes > of the mailbox file and do not rely on atime (because they saved the previous > mtime). Without atime updates, some application may claim that you have new > mail when the mailbox is not empty when they first start. > > That's said, if I were you and I'm using some flash based storage (with rpi > it's highly likely) regardless if I'm using mail locally; most of the time > the data is not really useful for anything, and it does increase the wear of > your storage. > > This reminds me that -- we probably should have implemented the Linux > "relative atime" (update atime iff (atime <= mtime || atime <= ctime) || > atime is older than a day) and "no diratime" (don't update directory atime) > for UFS and make the "relatime" option the default; I had an incomplete > implementation about a decade ago somewhere but with the recent VFS changes > it's probably easier to start over. IMHO, updating atime every time when a > file is accessed is not really providing useful data (like who accessed the > file, etc.) for audit purposes and does come with performance (more write > I/O) and reliability (wear of SSD and other flash devices) cost, therefore > not generally useful in modern days. The Linux relative atime is a pretty > clever idea that has covered the most useful use case for atime (Did I > accessed the file after it was last modified) and also provided a > coarse-grained update (capped to daily, which is a reasonable compromise) to > the atime. > > Cheers,
On the Linux side of things I think almost of the mail handling programs have migrated to either using MailDir or MH style mailboxes, which don't need atime, for anything local. The MDA/MTA configuration examples have all used MailDir for around a decade now. Why not make noatime the default across the whole system? Outside of mbox why is recording access time actually useful?
