Exports and named pipes

From: louis.avrami..jr <lou2_at_cbnewsg.cb.att.com>
Date: Thu, 22 Sep 1994 18:44:22 GMT
Message-ID: <CwJo1y.Hon_at_cbfsb.cb.att.com>

I am experiencing an interesting problem when trying to export my tablespaces to a named pipe. This is probably more of a UNIX problem than an ORACLE problem, but I thought that perhaps someone else out there might have experienced something similiar. Anyway, here's the problem:

        I am trying to export directly to a named pipe, as described in the O'Reilly book ORACLE PERFORMANCE TUNING, pages 430-431. Here is the code

        mknod ${ii}.dmp p # create named pipe

        cat ${ii}.dmp | compress > ${ii}.dmp.Z &

	exp USERID=${UID}/${UID} FILE=${ii}.dmp GRANTS=N INDEXES=N 
		BUFFER=409600 TABLES=${TABLE_NAMES}

	(the above line containing exp has been split in two for readability)

	On my production machine, an NCR 3555, 4 Pentium processors, 500 meg

of memory, running UNIX System V Release 4.0 Version 3.0, the above commands take approximately 10 minutes per tablespace, for a total of 40 minutes for the entire database. On my test machine, an NCR 3455 with 4 Pentium processors, 500 meg of memory, running UNIX System V Release 4.0 Version 3.0, it takes 2 to 3 times longer for each tablespace. On the NCR 3455, the entire database export takes approximately 2 1/2 hours. To my knowledge, the machines are tuned identically. My guess is that this problem must be with the named pipes. When I export the tablespaces and then compress the file, the running time on the two machines are identical.

        Could the discrepancy perhaps be traced to Interprocess Communications?

        Any help, hints or guesses would be greatly appreciated.

Lou Avrami ( attmail!lavrami ) Received on Thu Sep 22 1994 - 20:44:22 CEST