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Re: Very high 'log file sync' wait time with no 'log file parallel write' wait time

From: joel garry <joel-garry_at_home.com>
Date: 4 Dec 2006 14:24:49 -0800
Message-ID: <1165271088.331665.313750@n67g2000cwd.googlegroups.com>

EscVector wrote:

> The question I should have asked is why not just increase UNDO. What's
> the issue with that? UNDO is cheap compared to trying to debug why a
> commit is happening when one should not during a imp with large buffer
> and commit=y... Question, does the wait happen if the commit=y is
> removed. If not, nuff said... Up Undo, get it done. For educational
> purposes, then fine, keep it going, probably a bug, open a tar.

Well, I don't know about the OP, but on one system, if I increased undo to where a script tells me it "should be," I would have to quadruple the tablespace from 10G to 40G. Now, that system has two days online full backups available, so that means an additional 90G. I will be running some significant updates on that db within the next month, and they generate enough archives to already require me to get rid of one of the backups to have enough room, as the arcs take 3 days to drop off. It's not cheap when your SAN is already maxed out with disk. It's inevitably a balancing act. (Actually there is enough unallocated disk to avoid getting rid of the backup, but enough other things are going on, like physically moving a big chunk of the company including all the servers, that the sysadmins are already overworked and really shouldn't deal with any changes at this time, even if I did it for them.) So you really have to watch out for assuming what "cheap" means.

jg

--
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Received on Mon Dec 04 2006 - 16:24:49 CST

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