Date: Sun, 14 Jan 2024 10:58:13 -0700 From: Warner Losh <imp@bsdimp.com> To: "Lyndon Nerenberg (VE7TFX/VE6BBM)" <lyndon@orthanc.ca> Cc: Olivier Certner <olce@freebsd.org>, Rick Macklem <rick.macklem@gmail.com>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: noatime on ufs2 Message-ID: <CANCZdfosFb1xQdRL9rW1icbVAYbspqnKwWR4CO2guVd5LAv4HA@mail.gmail.com> In-Reply-To: <a5e3a25e0d57d1a9@orthanc.ca> References: <ZZqmmM-6f606bLJx@int21h> <a5e38bfbabd37084@orthanc.ca> <CAM5tNy4HuHb=GpQXvE4h2NC8_azOwDS3H7wY3UK%2BcE07owPr3A@mail.gmail.com> <4014880.cjyAsbXg9l@ravel> <a5e3a25e0d57d1a9@orthanc.ca>
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--000000000000cc2fc6060eeba4fb Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sun, Jan 14, 2024, 10:24=E2=80=AFAM Lyndon Nerenberg (VE7TFX/VE6BBM) < lyndon@orthanc.ca> wrote: > > > I do not have a strong opinion w.r.t. atime, but I do believe that > > > changing the default would be a POLA violation. > > I'm not prepared to just accept that at face value. > > I can't think of a single instance in at least the last three decades > where I have actually used or needed atime for *anything*. And > over that time period I have been responsible for running hundreds > of UNIX servers. > > I'm really interested in hearing from people who actively use > atime on a regular basis for non-trivial purposes. What are > the modern use cases for atime? > The consensus was we'd fix it in the installer. We can't change ZFS easily, and discovery of the problem, should your assertion be wrong, for UFS means metadata loss that can't be recovered. By pushing to the installer, most installations get most of benefits. And people with special needs see the issue and can make an informed choice. Though in all honesty, I've never been able to measure a speed difference. Nor have I worn out a ssd due to the tiny increase in write amp. Old (<100MB) SD and CF cards included. This includes my armv7 based dns server that I ran for a decade on a 256MB SD card with no special settings and full read/write and lots of logging. So the harm is minimal typically. I'm sure there are cases that it matters more than my experience. And it is good practice to enable noatime. Just that failure to do so typically has only a marginal effect. Warner --lyndon > > --000000000000cc2fc6060eeba4fb Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"auto"><div><br><br><div class=3D"gmail_quote"><div dir=3D"ltr" = class=3D"gmail_attr">On Sun, Jan 14, 2024, 10:24=E2=80=AFAM Lyndon Nerenber= g (VE7TFX/VE6BBM) <<a href=3D"mailto:lyndon@orthanc.ca">lyndon@orthanc.c= a</a>> wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin= :0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">> > I do not= have a strong opinion w.r.t. atime, but I do believe that<br> > > changing the default would be a POLA violation.<br> <br> I'm not prepared to just accept that at face value.<br> <br> I can't think of a single instance in at least the last three decades<b= r> where I have actually used or needed atime for *anything*.=C2=A0 And<br> over that time period I have been responsible for running hundreds<br> of UNIX servers.<br> <br> I'm really interested in hearing from people who actively use<br> atime on a regular basis for non-trivial purposes.=C2=A0 What are<br> the modern use cases for atime?<br></blockquote></div></div><div dir=3D"aut= o"><br></div><div dir=3D"auto">The consensus was we'd fix it in the ins= taller.</div><div dir=3D"auto"><br></div><div dir=3D"auto">We can't cha= nge ZFS easily, and discovery of the problem, should your assertion be wron= g, for UFS means metadata loss that can't be recovered.</div><div dir= =3D"auto"><br></div><div dir=3D"auto">By pushing to the installer, most ins= tallations get most of benefits. And people with special needs see the issu= e and can make an informed choice.</div><div dir=3D"auto"><br></div><div di= r=3D"auto">Though in all honesty, I've never been able to measure a spe= ed difference. Nor have I worn out a ssd due to the tiny increase in write = amp. Old (<100MB) SD and CF cards included. This includes my armv7 based= dns server that I ran for a decade on a 256MB SD card with no special sett= ings and full read/write and lots of logging. So the harm is minimal typica= lly. I'm sure there are cases that it matters more than my experience. = And it is good practice to enable noatime. Just that failure to do so typic= ally has only a marginal effect.</div><div dir=3D"auto"><br></div><div dir= =3D"auto">Warner</div><div dir=3D"auto"><br></div><div dir=3D"auto"><div cl= ass=3D"gmail_quote"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0= .8ex;border-left:1px #ccc solid;padding-left:1ex"> --lyndon<br> <br> </blockquote></div></div></div> --000000000000cc2fc6060eeba4fb--
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