BACKUP uses nearly 100% CPU

[Shriniketan Bhagwat]

Hi,

What is the length of encryption key used?
Encryption strength is often described in
terms of the length of the encryption key
used to perform the encryption. In general,
longer encryption keys provide stronger
encryption and shorter encryption key
provides faster BACKUP.

Thanks and Regards,
Ketan

[Volker Halle]

Stephen,

if you are really interested (beyond just speculating), in which routines/libraries BACKUP spends it's CPU time, you can use the PCS SDA extension (PC-sampling):

$ ANAL/SYS
SDA> PCS ! to display help information
SDA> PCS LOAD
SDA> PCS START TRACE
... wait a while while backup is running...
SDA> PCS STOP TRACE
SDA> SET PROC/IND=
SDA> PCS SHOW TRACE/STATIS
SDA> PCS UNLOAD
SDA> EXIT

This will tell you, how often a specific PC value is being observed and SDA will try to symbolize those PC values. I assume you will recognize, where the majority of PC samples will be spent...

Note that a second CPU may NOT speed up this encypted backup, if the encryption operation cannot be multithreaded (is it using PTHREADS ?). A second CPU will provide capacity for other processes to execute.

Volker.

[Nikus Giri]

If you are using encryption, then it may consume high CPU. Why are you concerned with high rate of CPU consumption? Is it performance of the other application?
Currently, BACKUP does not have any control over data scan or throttling output.

[Hoff]

>Currently, BACKUP does not have any control over data scan or throttling output.

Output can be throttled with /IO_LOAD on OpenVMS versions where that qualifier is available (or if and as that gets back-ported?), and that tends to back-pressure the input scan.

the Alpha EV6 and EV7 processors don't compare well with Itanium nor all that well with current x86-64 processors; they're older.

If you need to offload the Alpha box, I'd tend to suggest using an Integrity as a BACKUP and compute server. The used hardware boxes and the current FOE base license can be quite affordable, though the cluster license cost was (when last I looked) comparatively huge (regardless of platform) part of any OpenVMS purchase.