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Home -> Community -> Usenet -> c.d.o.server -> Re: Fssnap and Oracle 9i
Joel Garry wrote:
> "Howard J. Rogers" <hjr_at_dizwell.com> wrote in message
> news:<41705773$0$24889$afc38c87_at_news.optusnet.com.au>...
>> Joel Garry wrote: >> >> > "Howard J. Rogers" <hjr_at_dizwell.com> wrote in message >> > news:<4167074d$0$23893$afc38c87_at_news.optusnet.com.au>... >> >> Roel Toledo wrote: >> >> >> >> > Id' like to solicit opinions from other DBA's in this forum about >> >> > Solaris 9's online backup utility fssnap and using it to backup an >> >> > Oracle database server. Do the database instances need to be shut >> >> > down first before issuing fssnap? In the event that fssnap backup >> >> > is made while the database is up and running, can the backups be >> >> > safely restored without a problem? >> >> >> >> I don't know fssnap, so I could be wrong. But I do know Oracle's >> >> internal shenanigans that get stuffed by O/S backups done incorrectly, >> >> so I'll bet I'm not. >> > >> > >>
>> > >> >> >> >> The instances would indeed need to be shutdown before taking your >> >> backup. The problem is simply a generic one: an operating system >> >> utility cannot know the significance of the first block in a data >> >> file's header. Nor can it understand that 16 512 byte blocks need to >> >> be copied in synchronism before you can say you've backed up one >> >> Oracle block. Only an Oracle-aware utility can do that (such as RMAN). >> >> Therefore, if the instances are still running, you risk fractured >> >> blocks and inappropriate data file headers. >> > >> > Isn't that what hot backups are for? >> >> Joel: could you try to note what the actual topic of conversation here >> is, before joining in? The OP wrote, "I'd like to solicit opinions about >> fssnap". >> >> *My* comments are addressing his question. >> >> What are your comments doing?
The original poster wrote: "Will fssnap safely backup a running Oracle database?" I wrote: "You can't just copy Oracle files hot. If that's what fsnap is doing, it's doomed"
It was at that point you decided to remind everyone that Oracle can do hot backups. We *know* that, Joel. Of course the guy could put all tablespaces into hot backup mode and then fssnap. But that's not what he was proposing to do, or asking about. His question clearly indicates that he wants to know whether an fssnap backup *on its own* is safe as a backup method.
So, to answer your specific question: "perhaps you can explain in short sentences why an instance has to be shut down and hot backups don't work"... Not "an instance", Joel. *HIS* instance. The instance belonging to the guy who's actually asking the question about fssnap. HIS instance has to be shut down because the product HE is using is not capable of taking the backup hot. Not safely, anyway. And of course hot backups DO work. As you know that I know very well. But HE isn't doing hot backups as we know them and would call them. HE is asking whether fssnap can be used, solo, with a hot database.
> I was saying they work,
> but they are operationally stupid for fssnap type use. If I'm wrong
> about when Oracle writes to files, that's fine too, please explain.
There's nothing to explain except that you seem to have missed the entire point and context of the original post and my reply.
>> Yes, we know that Oracle has a hot backup capability. But the question >> was actually, how good is fssnap.
I didn't notice a plethora of fssnap experts piling in to reply to him, did you?
It's not like I falsely advertised expertise, Joel. My reply gave him the information he needed to go and ask the product vendor: is this product Oracle-aware or not? In the same way you could ask whether ArcServe is Oracle aware. Or BackupExec. If not, it can't be used to backup a hot Oracle database. Period.
> Come on, Howard, this is a usenet group, where oftentimes bits and
> pieces of an answer can come from various sources.
The guy asked about a particular product. You decided to refer to something he hadn't asked about at all, and in the process decided to try to make my reply look like it was technically deficient and ill-informed. It wasn't.
> Thread drift can
> actually help.
Right, so we're talking about "thread drift" rather than answers 'coming from various sources', are we? Make your mind up. Multiple sources for answers I have no problem with. Thread drift I do: it's called being off-topic. And if you want to drift a thread, be my guest... but don't make me out to look stupid or wrong when you do it, OK? Unless I am being stupid or wrong, of course. But in this case, I wasn't.
> The OP appears unfamiliar with the way Oracle and OS
> utilities interact, and indeed you should look at subject line again.
Yes, I just did. It mentions Oracle 9i. It mentions Fssnap. It doesn't mention "how do hot backups work". Or "is it possible to do hot backups". The guy wanted to know whether Fssnap is a viable way of backing up a running database. I gave him the theoretical underpinnings as to why it may or may not be safe.
> A strict limitation to fssnap would not be addressing the subject.
What?! His subject line mentions two products. His question asks whether one of those products can backup the other of those products. My answer answered that. Yours talked about a hot backup capability he hadn't asked about at all.
So if a poster asks about RMAN, does replying that 'In SQL Server, we right-click and select 'backup'' count merely as thread drift or a complete, non-helpful, non sequitur? The latter, I think. You of course are free to continue thinking whatever you like.
> Certainly the thread context
Thread subject or context? Multiple sources for answers, or thread drift? You keep changing your mind on these sorts of issues, Joel. I am ineluctably drawn to the conclusion that you just wanted to say something smart in this thread that would make me look a bit wrong, a bit stupid, a bit technically deficient. You do it quite frequently, and not just to me, either.
> extends the question to "I'd like to
> solicit opinions about" how OS utilities and Oracle interact.
You can extend threads any way you see fit. I can't stop you. But you might just pause to consider whether your "extension" actually answers the question asked, helps the original poster, or merely makes you look wise and all-knowing (and usefully makes others look daft).
HJR Received on Mon Oct 18 2004 - 17:34:46 CDT
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