Re: [EXTERNAL] Re: rman backup slow even after patching it

On 8/16/22 09:44, Beckstrom, Jeffrey wrote:
>
> In a rare factual error my friend Mladen missed that the list is
> ascending.
>
> Still probably a network issue. Smirk. Unless that is backup &
> recovery read time (The key thing that **might** tell you a **lot**
> would be separation of I/O into I and O). I cannot remember their
> detailed description of this event and I’m too lazy to too it up. But
> I did re-arrange the output for that one line into “What” and useful
> “How much” columns.
>
> Notice that the “also ran” second place was only about a minute of
> total wait. So this one bundled line for I and O is pretty much
> everything. So 41 milliseconds per I/O and I have no idea what a raw
> system level I/O between your source system and backup system is, or
> what size RMAN’s I/O unit is (min, max, average) as configured. If you
> have some idea of the total bytes written, you could do a system to
> system level I/O of that size (maybe a bundle of 100 or 1000 repeats,
> so any possible begin and end process time error is minimized) and get
> a clue whether I/O time between systems is the problem, rather than
> something more complex inside Oracle.
>
Of course, Mark is right. I am using similar kind of query with "DESC" option for the ordering so I assumed that Jeff does the same. Apparently, my assupmtion was wrong. Not only that, rman network communication doesn't use SQL*Net, so the "SQL Net data to client" message is unlikely to be caused by rman. It _*might*_, however, be indicative of a network problem. My advice would be to also check disk I/O and network throughput using the Linux tools like atop, iotop and iptraf-ng. Even strace can be useful in this situation. Also useful are "perf" tools, like "perf top" and system wide profilers like "oprofile".

You may need to open a case with Oracle or your backup vendor.

Regards

-- 
Mladen Gogala
Database Consultant
Tel: (347) 321-1217
https://dbwhisperer.wordpress.com

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