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

From: Michael McMullen <ganstadba_at_hotmail.com>
Date: Tue, 7 Dec 2021 16:07:46 +0000
Message-ID: <DM6PR15MB2938CF606819C38DC50AA470A66E9_at_DM6PR15MB2938.namprd15.prod.outlook.com>

basic compression for all systems

---

From: oracle-l-bounce_at_freelists.org <oracle-l-bounce_at_freelists.org> on behalf of Michael McMullen <ganstadba_at_hotmail.com> Sent: December 7, 2021 9:57 AM
To: oracle-l_at_freelists.org <oracle-l_at_freelists.org> Subject: slow rman compression on exadata x8-m to zfs

exadata x8-m high capacity - new
exadata x5-2,x6-2 - old
zfs storage
big file tablespaces
24 channels 128G section size
configure device type disk parallelism 24 backup type to backupset;

We're migrating, 11.2,12.2,18c databases from various exadata's to a new x8-m system. Db's are going from rac db's to container rac db's.

All the exadatas are using the same zfs for backups and backup scripts are the same.

We noticed the backups are reading at 500Mb/sec to the zfs on the new exadata. Previously they would read at 8-10Gb/sec on the older exadatas while using rman compression. They were all writing to the same zfs, so a mix of ib/roce/public infterfaces depending on the exadata.

If I remove compression on the rman backups on the new system then I get 8-10Gb/sec.

Everything seems to be ok at the network level, MTU etc.

I think I've narrowed it down to just the compression. CPU's are at 100% for the rman processes with compression and ~50% without. I'm not seeing that on the other exadatas.

Any ideas?

Thanks
Mike

--
http://www.freelists.org/webpage/oracle-l

Received on Tue Dec 07 2021 - 17:07:46 CET