Date: Wed, 23 Jul 2003 17:48:30 +0200 From: =?ISO-8859-1?Q?Rapha=EBl_Marmier?= <raphael@computer-rental.ch> To: Bill Moran <wmoran@potentialtech.com> Cc: questions@freebsd.org Subject: Re: maildir with softupdates Message-ID: <1B92DE8C-BD25-11D7-BDC6-000393D67E4A@computer-rental.ch> In-Reply-To: <3F1EAC04.10204@potentialtech.com>
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Basically, if you want to ensure that email wont get lost, put the=20 maildirs and mail queue on separate partitions and mount them sync.=20 This is what I do. If you have to speed things, try first a battery backed raid controler=20= and enable the write cache on it. Of course, you should always use an=20 UPS and some will say you can take the risk of enabling soft-updates=20 anyway. But realise that if you have only a small load on the mail server, then=20= having the partition mounted sync wont make such a big difference. If=20 you are under high load, when you need performance, you also need to=20 mount sync, as the potential of loss is much greater... just my two cents Raphael Le Mercredi, 23 juil 2003, =E0 17:38 Europe/Zurich, Bill Moran a =E9crit = : > Attila Nagy wrote: >> Hello, >> Is this statement still valid? >> "ext3 is unsafe for maildir, and with softupdates, so is ffs." >> http://www.irbs.net/internet/postfix/0202/0358.html > > Yes, > > It's also true that any form of write-caching is unsafe, so disable > the caches on your SCSI and ATA hard drives. Simply accept the > terrible performance hit if you want super-reliability. > Also, make sure you have redundant power supplies, UPSes and a diesel > generator out back to cover power problems. > > In reality, anything comes with a certain amount of risk, and that > statement is too vague to be useful. > > To my knowledge, ext3 is not unsafe by nature, it is simply unsafe > by default because the default mount is async - which will generally > be corrupted in the event of hardware failure. > > UFS+softupdates generally survives hardware failure without = corruption, > although it has a funny habit of losing files that were saved right > before the failure. Result being that you could lose emails. > However ... even a sync mount can become corrupt in the event of > hardware failure, although it's much less likely. > > So you need to determine the risk level you're willing to accept as > well as the performance you require. And you probably need to do more > research than accepting that one-line statement, as it's too vague to > properly describe the potential risk/benefits. > > This reminds me of the days when DOS first got disk-caching via a > TSR (what was the name of that thing) and all the IT folks kept saying > "Don't use it, it's dangerous" without understanding why it was > dangerous. I used it anyway, because it improved performance > considerably. > > Also, this is off-topic for -CURRENT, please remove -CURRENT from the > CCs if you respond. I'm redirecting to -QUESTIONS for future=20 > discussion. > > --=20 > Bill Moran > Potential Technologies > http://www.potentialtech.com > > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to=20 > "freebsd-questions-unsubscribe@freebsd.org"
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