64-bit Hash Files

nvalia · Post by **nvalia** » Fri Mar 13, 2015 10:21 am

Hi All,

We migrated from v7.5 on a 32 bit Windows Server to v9.1 on a 64 bit Windows server. We use Server Jobs Only

Post Migration we are having performance degradation in the newer version by almost 40% while I understand a 10% down performance can be expected due to the way Authentication works.
** No Code Changes made during upgrade **

We have done a lot of testing but have not been able to figure out why the same job in 9.1 is so slow compared to 7.5. Have raised a support request with IBM but that is not helping!!!!!

We use a lot of Hashed Files and currently both version have the variable 64BIT_FILES = 0 in the UVCONFIG file. Any chance changing this 64BIT_FILES = 1 in the v9.1 to use 64 bit Hash files instead of 32-bit could help in performance?

Thanks,
NV

chulett · Post by **chulett** » Fri Mar 13, 2015 11:51 am

Nope. At least I really don't believe so.

Does your performance hit seem to be related to hashed files reading and/or writing?

ray.wurlod · Post by **ray.wurlod** » Fri Mar 13, 2015 3:36 pm

Almost definitely not. 64-bit hashed files use 64-bit internal pointers, so take up more space on disk. Otherwise the access mechanism is identical to that for 32-bit hashed files (possibly with more seek activity within the file, which would actually make performance worse).