in fact, is safe to enable into compilation theses options ? or only is for the best performance of cyrus ? i not understand very well, is default on cyrus is safe into smp systems, or is only cyrus-2.1.x affected into smp ?
http://acs-wiki.andrew.cmu.edu/twiki/bin/view/Cyrus/WhatDatabaseBackend ---- Here's a brief summary of the three major database types: Berkeley DB: Slow enumeration, fast random access, fast write, binary support. However, it has proved to be somewhat unstable and prone to locking problems. Berkeley DB (no sync): Slow enumeration, fast random access, very fast write, binary support, but no guarantee of database durability; recent writes can be lost on crashes. Skiplist: Proprietary Cyrus Format, fast enumeration, moderately fast write, moderately fast random access, binary support Flat: Easy to maintain format, fast enumeration, very slow write, moderate random access, no binary support And now the current recommendations (provided you are not having the Berkeley DB locking problem, in which case those entries become 'skiplist'): Note that 'berkeley' in 2.2 is the same as 'db3' in 2.1. > --with-duplicate-db=DB use DB (db3, skiplist) as a backend > for the duplicate delivery db berkeley_nosync, since the worst part about losing this is that someone might get a vacation message twice. It also needs fast lookups. > --with-mboxlist-db=DB use DB (flat, db3, skiplist) as a backend > for the mailbox list skiplist. You need fast list operations and good consistency in the event of a crash. Also, since the mailboxes database is a frequent source of lock contention, the speed of skiplist writes reduces the amount of time any process is waiting to use the file. > --with-seen-db=DB use DB (flat, db3, skiplist) as a backend > for the seen state (Default: flat) skiplist. Writes happen very frequently to this file so the logging nature of skiplist can give good performance (it also helps to have good consistency here) > --with-subs-db=DB use DB (flat, db3, skiplist) as a backend > for the subscriptions list flat. You need fast list performance, and write operations don't happen often to this database, and it might be useful to be able to modify it by hand. Also, flat files tend to be smaller than skiplist copies of the same data. > --with-tls-db=DB use DB (db3, skiplist) as a backend > for the TLS cache (Default: db3_nosync) berkeley_nosync . for the similar reasons to the deliver database (you need fast lookups and if the db bites the dust, it's not a big deal). The following are only available in 2.2 > --with-pts-db=DB use DB (berkeley, skiplist) as a backend > for the pts cache berkeley. The need for fast random access is key for the PTS database. This database may be able to be successfully used in a nosync mode, though writes tend to be semi-infrequent compared to the TLS db and the deliver DB. > --with-annotation-db=DB use DB (berkeley, skiplist) as a backend > for the mailbox annotations skiplist. annotations are frequently enumerated, so the random access benefits of berkeley can be lost, which makes this almost a toss up, slightly in favor of skiplist (Because it avoids the locking issues). Cesar Lagarrigue V. Project Engineer [EMAIL PROTECTED] Rob Siemborski <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] 26-02-2004 11:02 To Etienne Goyer <[EMAIL PROTECTED]> cc [EMAIL PROTECTED] Subject Re: Are there large installation of Cyrus who use db3 for mailboxes.db on SMP Linux ? On Thu, 26 Feb 2004, Etienne Goyer wrote: > For the sake of comparison and help me pinpoint my problems, I would > like to know if anybody with a large Cyrus installation use Berkeley db > for mailboxes.db on SMP Linux system, just like us. Note that db3 is > the default, so if you did not change it, you probably use it. ...unless you are using Cyrus 2.2, where Skiplist is the default. -Rob -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Rob Siemborski * Andrew Systems Group * Cyert Hall 207 * 412-268-7456 Research Systems Programmer * /usr/contributed Gatekeeper --- Home Page: http://asg.web.cmu.edu/cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html --- Home Page: http://asg.web.cmu.edu/cyrus Wiki/FAQ: http://cyruswiki.andrew.cmu.edu List Archives/Info: http://asg.web.cmu.edu/cyrus/mailing-list.html
