On Friday/Saturday, I noticed that 4GB of swap space was consumed by the O/S, and that this server has 23GB of RAM - but today, on the now quiet system, zero swap space is currently in use.
IMO, a NetBackup master/media should not be making use of any swap space.
My rough calculations are:
RHEL O/S 6 GB
NetBackup application 8 GB
NetBackup buffers 2 GB (although not configured at the moment)
MSDP (1.5 * 10TB) 15 GB
...so, possibly, this system should have at least 31GB of RAM - which might go some way to explain why I saw 4GB of swap space used during busy periods.
I don't know enough about RHEL O/S to know whether recalling lots of data from O/S swap space consumes CPU or where that CPU time/cost is charged too - so I don't know whether the use of swap space was somehow causing CPU cycles to be consumed within the bpdm processes when I saw them hitting 100%.
Anway, I grabbed the bptm data consumer wait and delay times (from the activity monitor job log for the duplication jobs) and there's many hours lost for bptm waiting for full buffer, but unfortunately, I didn't have logging enabled at the time, so I don't have the bpdm data producer waits/delays for empty buffer - but I did some further duplication testing (with logging enabled) on a small-ish (15GB) backup image and bpdm was spending some time waiting too - but during the duplication test (from MSDP to tape) I didn't see the bpdm process go above an average of 35% of a CPU core.
The LTO6 tape media (2.5TB native) which did reach full, both show as circa 3.5 TB occupied - so the tape drive heads are definitely able to SCSI T10 compress the incoming data - which says to me that the tape drives are not receiving 'encrypted or compressed' data to write.
I had previously enabled MSDP encryption at rest (in the pd.conf file), so I'm now wondering if maybe something about the mixture of NetBackup and RHEL and the Intel CPU model/type inside the server tin is altogether somehow not very good at decrypting the MSDP de-duped data blocks read from MSDP pool.
Does anyone know where the 'encryption/decryption' of NetBackup MSDP is performed? I mean, is encryption/decryption performed by:
a) software local to NetBackup MSDP, i.e. do Symantec use their own software routines.
b) or does NetBackup call a RHEL O/S library routine to perform encryption/decryption
c) or does NetBackup (and/or the O/S library call) make use of some extended hardware instructions within the Intel CPU itself?
d) or maybe, it's option c) first, and if the required CPU hardware instructions for encryption/decryption are not present within the CPU model, then option b) or a) is performed.
Which then makes me want to ask, how do I actually determine where NetBackup MSDP encryption/decryption is peformed?
Thanks.