A couple of things to consider - Linux does not write to the device. It writes to the page space, then the page manager, driven by bdflush, writes to the device. So you would not expect as high a performance under Linux as you would for MVS.
I/O is backed up behind a single subchannel to a single device, so the maximum you would expect is "17 mb/sec". Personnally, I have never seen anything over 15 mb/sec with assembly level programming and BSAM. If you have multiple data sets open on a single device, then the queue time (wait for the I/O to actually start) can be large, artificially slowing the I/O (that's what PAV's amelioriate). In Linux, the best solution seems to be to use RAID0 for striping or LVM for striping, allowing multiple subchannels to be active at the same time. As to shark, the speed to a single raid array is much less that you would expect - 40-60 mb/sec, even if the box is rated at 150-300 mb/sec. To get maximum throughput, the stripes should be over as many raid arrays (LCU's) as possible. ===== Jim Sibley Implementor of Linux on zSeries in the beautiful Silicon Valley "Computer are useless.They can only give answers." Pablo Picasso __________________________________ Do you Yahoo!? New Yahoo! Photos - easier uploading and sharing. http://photos.yahoo.com/
