Date: Sun, 2 Oct 2011 15:24:39 +0100 From: Chris Rees <crees@freebsd.org> To: Olivier Smedts <olivier@gid0.org> Cc: freebsd-fs@freebsd.org, delphij@freebsd.org, Adrian Chadd <adrian@freebsd.org> Subject: Re: is TMPFS still highly experimental? Message-ID: <CADLo839H2TBLpmLLmb8aR5tYMgfRX_Fipaz3kcjRr%2BcOpepvZA@mail.gmail.com> In-Reply-To: <CABzXLYOuunKT6pQ3Jpb4J10LHvyKHEuom47s2%2B5D7vXZczYw7A@mail.gmail.com> References: <CAOfDtXMm9K_fbOmvG2gvXxDfKakkgpPt9MLifqDxa4wCibMExg@mail.gmail.com> <alpine.GSO.1.10.1110011122030.882@multics.mit.edu> <CADLo83-s_3H8PbbxOPPxbe0m10U0U5JW-feB294dFs%2BQ3iTWvg@mail.gmail.com> <CAGMYy3ssi%2BkAuufDTHA1z6u7jRrZwRRkCCkcO94GHNGF9Rku_w@mail.gmail.com> <CABzXLYOuunKT6pQ3Jpb4J10LHvyKHEuom47s2%2B5D7vXZczYw7A@mail.gmail.com>
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On 2 October 2011 11:23, Olivier Smedts <olivier@gid0.org> wrote: > 2011/10/2 Xin LI <delphij@gmail.com>: >> Hi, >> >> On Sat, Oct 1, 2011 at 8:48 AM, Chris Rees <crees@freebsd.org> wrote: >>> I've also not heard of anyone using it with zfs successfully- it tends = to >>> shrink rapidly. >> >> I'm quite surprised with this assertion. =A0I use tmpfs on my own system >> and I never see such problem as long as one have sufficient swap >> space. > > The problem here is "sufficient swap space". > > I've got 8G of RAM, and 2G of swap (just in case). When the ZFS ARC > reaches 4G, there's no room for a single byte in tmpfs, even with 2G > swap free and at least 2-3G RAM free. The swap size must be at least > the RAM size if you plan on using ZFS and tmpfs. That's a problem for > me because I'm short on disk space, and there's no point in having an > enormous swap size (hey, minidumps !) when you already have lots of > RAM, which is the case in most ZFS installs. > It's common practice to set the swap size equal to or more than the physical RAM size, as well as assumed in many places-- how could you have a crash dump otherwise? Unfortunately you probably won't get a 'fix' to allow swap<RAM. It's not just for 'virtual memory' usage, after all. Chris
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