Date: Thu, 26 Sep 2002 14:44:06 -0400 (EDT) From: Zhihui Zhang <zzhang@cs.binghamton.edu> To: Claus Assmann <freebsd+current@esmtp.org> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Journaled filesystem in CURRENT Message-ID: <Pine.SOL.4.21.0209261442240.3462-100000@onyx> In-Reply-To: <20020926113551.A11092@zardoc.esmtp.org>
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On Thu, 26 Sep 2002, Claus Assmann wrote: > On Thu, Sep 26, 2002, Terry Lambert wrote: > > Claus Assmann wrote: > > > > When we tested several filesystems for mailservers (to store the > > > mail queue), JFS and ext3 (in journal mode) beat UFS with softupdates > > > by about a factor of 2. > > > > Hi Claus! Nice to hear from someone who actually tests things! > > > > I think that what you were probably testing was directory entry > > layout and O(N) (linear) vs. O(log2(N)+1) search times for both > > non-existant entries on creates, and for any entry on lookup > > ( / 2 on lookup) . > > I doubt it. The number of files in the queue directories was fairly > small during the runs. Moreover, ReiserFS showed fairly poor > performance, even though it should be "good" for directory lookups, > right? > > > The best answer for inbound mail is to go to per domain mail > > queues, and the best for outbound is to go to hashed outbound > > domains (as we discussed at the 2000 Sendmail MOTM gathering). > > Per domain mail queues inbound give you a 100% hit rate on > > a directory traversal for a queue flush; using hashed outbound > > directories isn't a 100% hit rate, but you can keep it above > > 85% with the right hashing structure, which makes the miss > > rate have only 1-2% impact on processing. > > "Per domain" doesn't work easily if you have multiple recipients. > Anyway, the new design clearly distinguishes between the content > files and the data that is necessary for delivery. > > If someone is interested: > http://www.sendmail.org/~ca/email/sm-9-rfh.html > > Just as a small data point: I get message acceptance rates of > 400msgs/s on a journalling file system (using a "normal" PC) that > writes the data into the journal too. AFAICT that's due to the fact > that fsync() is much fast for this kind of storage. > > The important part for mailservers here is the rate at which content > files can by safely written to disk. From my limited experience > journalling file systems are here much better than softupdates. Can you tell me the approximate sizes of these mails and how they are stored? -Zhihui To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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