Re: slow rman compression on exadata x8-m to zfs

On 12/7/21 12:53, Michael McMullen wrote:
> Backups are run from a separate vm, but it doesn't matter. rman
> target=/ gives the same result.
> I've set compression on the zfs. Just trying to find a root cause.

Hi Mike,

You should also get Oracle involved and open a SR. Oracle provides very comprehensive support for their engineered systems. You should also do strace on the rman processes and see where do they spend time. You can also use perf record -p <pid> to record where the processes are spending time. It looks like the most of your rman channel processes are sleeping. 500 MB/sec  is what only a single channel should be able to do. You should be able to find out by using ps -ef|grep rman Please run rman with debug=all log=/tmp/rman_debug.log parameters.

To tell the truth, this looks like a bug in rman, changing behavior when compression is used.

Regards

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


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