Date: Wed, 23 Jul 2003 11:38:44 -0400 From: Bill Moran <wmoran@potentialtech.com> To: Attila Nagy <bra@fsn.hu> Cc: current@freebsd.org Subject: Re: maildir with softupdates Message-ID: <3F1EAC04.10204@potentialtech.com> In-Reply-To: <3F1E6456.9090400@fsn.hu> References: <3F1E6456.9090400@fsn.hu>
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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 discussion. -- Bill Moran Potential Technologies http://www.potentialtech.com
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