High CPU WIO on backup server?

[Mott Given]

We have an N4000 with 4 CPU's and 6.1 GB RAM running HP-UX 11.11. This machine is used for backups. Sar and BMC Patrol data show that the "CPU WIO" is 90-99% when the machine is busy. I wonder if this indicates a real performance problem or if this is an artifact from sar and Patrol not being able to read the performance data accurately. Glance is not installed on this box.

P.S. This thread has been moved from Disk to HP-UX > sysadmin. - Hp forum Moderator

[Leif Halvarsson_2]

Hi,
Seems as the processes is waiting for I/O, this indicates a I/O bottleneck rather then a cpu bottleneck. Is it possible for you to describe your enviroment more in detail (backup application, number of clients, backup devices etc.)

[Mott Given]

There 20 some machines that are being backed up with Veritas software. The machines being backed up are Superdome partitions, N4000 boxes, and around 50 Windows servers. The STK silo being used has 10 fiber pair cables going to 10 tape drives, and 1 fiber pair cable going to NT servers. An EMC Connectrix is connected to the backup server. The HP servers are going through 2 Cisco 6009 switches through a 100 full/Ether link to the backup server.

[Leif Halvarsson_2]

Hi,
A high wio value when running backup does not nessecary indicates any bottleneck, rather that backup applications is I/O intensive more then cpu intensive. I run a test backup on our OmniBack server (A400, SAN LTO library, local disk) and got wio figures of 85 to 95% (but normal backup performance). If your backup performance seems normal (depending on the drive type and amount of data you backup) I dont think you need to worry.