Re: Un-attended Large Archives (fwd)

Graeme Sargent writes: |> Dave Kosenko wrote: |> >You imply that, by design, the system is intentionally locked during media |> >changes and this is incorrect. In fact, this problem can generally be |> |> I think you're being a bit pedantic here, Dave. The lockup effect may |> not be implemented as a "Global Lock" but nevertheless the effect is |> that of a global lock. Pedantic or not, I feel it very important that it be understood that a lock is not placed, but rather that it is the result of other things happening. [ regarding my preference for infrequent checkpoints ] |> But what does this do to your Fast Recovery times??? We are trying to |> implement highly available systems here. We frequently get asked to |> provide recovery times after powerout of the order of 3 minutes. Since |> the system requires longer than this to boot and fsck, every second I |> can save on Fast Recovery is valuable, thus it is tempting to *increase* |> checkpoint frequency to the 30 - 60 second range. The balance is throughput vs. recovery time. Every customer must choose the point of balance appropriate for their application. Many customers will choose to add a minute or two to the recovery period in order to see better throughput during uptime. Others, like yourself, are more concerned with a fast return to operability. Note that some 6.0 features will make checkpoints a bit less of a drag on throughput. |> Incidentally do you (or anybody else) have any suggestions for how to |> predict average Fast Recovery time? At this point, no. You best bet is to run some tests on your system (since the profile of your transactions are the determining factor) and extrapolate. |> I get the impression that this tape change/lockup problem is perceived |> as relatively low priority by Informix, whereas it is a *BIG ISSUE* for |> us, and I'm sure for any large site. What is the point of having an |> Online Archive facility if using it freezes your system as soon as you |> go beyond one tape unless your tape operator a) is on his/her toes and |> b) has nothing else to do??? You have received the wrong impression. The 6.0 release will include an entire tape management subsystem, which will give a great deal of flexibility in dealing with archiving large systems (e.g. dbspace level archives, supporting multiple devices for a single archive, etc.). It is very well understood that backups are an essential part of any successful system, and we are working on improving the tools and mechanisms available for achieving a successful strategy. |> I hope someone in Informix will tell me that my impression is wrong! See the above. Dave Disclaimer: These opinions are not those of Informix Software, Inc. ************************************************************************** "I look back with some satisfaction on what an idiot I was when I was 25, but when I do that, I'm assuming I'm no longer an idiot." - Andy Rooney