Recordlength & buffer parameter in IMP

Question

In IMPORT of oracle we specify 2 parameter
1. recordlength
2. buffer
1. How much maximum size we can spercify for those parameter to fasten the IMPORT process? Also on which thing those values depends?
2. Also how much time will it save if we specify those parameters? e.g. If any IMPORT takes 10 Hours to import and if we specify those 2 parameters to high values then how much will it take to import?
3. Is there any other parameter which will fasten the import process?
Thanks,

Answer 1

for first You have to understand what those parameters mean:
The BUFFER parameter applies ONLY to conventional path Export. It has no effect on a direct path Export. This BUFFER parameter specifies the size (in bytes) of the buffer used to fetch rows. It determines the maximum number of rows in an array, fetched by Export. For direct path Export, use the RECORDLENGTH parameter to specify the size of the buffer that Export uses for writing to the export file.
The RECORDLENGTH parameter specifies the length (in bytes) of the file record. You can use this parameter to specify the size of the Export I/O buffer (highest value is 64 kb). Changing the RECORDLENGTH parameter affects only the size of data that accumulates before writing to disk. It does not affect the operating system file block size. If you do not define this parameter, it defaults to your platform-dependent value for BUFSIZ (1024 bytes in most cases).
Then read metalink note: 155477.1
Or this one:
http://www.dba-oracle.com/oracle_tips_load_speed.htm
Then test in Your test env what are the best parameters for Your particular system.