<!DOCTYPE html><html><head><title></title><style type="text/css">p.MsoNormal,p.MsoNoSpacing{margin:0}</style></head><body><div style="font-family:Arial;"><br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">On Sat, 1 Dec 2018, at 01:32, Дилян Палаузов wrote:<br></div><blockquote type="cite" id="fastmail-quoted"><div style="font-family:Arial;">Hello,<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">> > 3: if your DB is larger than RAM, writing thru mmap is slower than using write() syscalls. Whenever you<br></div><div style="font-family:Arial;">> > access a page for the first time, the OS will page it in. This is a wasted I/O if all you're doing is<br></div><div style="font-family:Arial;">> > overwriting the page with new data.<br></div><div style="font-family:Arial;">> <br></div><div style="font-family:Arial;">> I doubt it... especially now we're running on servers with 256Gb of data. These databases are usually under a gigabyte in size. I also don't think we ever overwrite a page without reading from it first - we're usually updating pointers which we've just had to read.<br></div><div style="font-family:Arial;">> <br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Are there recommendations on RAM for running cyrus imap, that reflect<br></div><div style="font-family:Arial;">this aspect?<br></div></blockquote><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Yes ram is cheap :P</div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Seriously though, we budget for 120 bytes per message in open mailboxes, so if you probably want at least 1 gigabyte ram per 100 users on a machine.<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">If you turn on conversations support (needed for jmap) I would multiply by 4 to allow for the databases there, though jmap doesn't hold as much in ram between connections. Most of the benefit really comes from caching, particularly if you have data on non SSD storage, so the more the better.<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;">Bron.</div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;"><br></div><blockquote type="cite" id="fastmail-quoted"><div style="font-family:Arial;">Greetings<br></div><div style="font-family:Arial;"> Dilyan<br></div><div style="font-family:Arial;"><br></div><div style="font-family:Arial;"><br></div></blockquote><div style="font-family:Arial;"><br></div><div id="sig56629417"><div class="signature">--<br></div><div class="signature"> Bron Gondwana, CEO, FastMail Pty Ltd<br></div><div class="signature"> brong@fastmailteam.com<br></div><div class="signature"><br></div></div></body></html>