Sparta PCBoard Hard Drive Conference (201) 729-7056 August 8, 1987 This is the second in a series of informational files about the Perstor 200 series hard drive controllers... The model PS180 and model PS200. Drive Tables ____________ Perstor will soon be issuing new BIOS Eproms for the PS180 and PS200 controllers that will have 16 hard drive table entries contained in the Eprom. You will be able to select from one of four tables, with each table containing information for 4 drives. This should reduce the number of controllers shipped that have to have a new Eprom burned to match your hard drive configuration. Of course, we will still be able to burn HD track and cylinder information into the Eprom if you have a drive that is not included in the factory Eprom. Interleave Determination ________________________ A subject that always makes for lively discussion. I have been asked many times about the factory recommended interleave value that may seem awfully high compared to one that you might have been using with a standard 2,7 RLL controller such as the OMTI. I have also inquired of Perstor about those values. Their reply was essentially what I thought it would be. The interleave values are subject to change according to system components that make up the whole system, not just the controller and hard disk. The factory recommended settings are actually halved by the Perstor BIOS because of the interleave skew pattern that is put on the drive by PS2FMT when doing the low level format. If you specifiy an interleave of 4, then your transfer rate should be equal to or better than if you had used an interleave of 2 on an OMTI. The bottom line on what the interleave should be for your configuration should be based on your own testing of the system as a whole. Different systems, at different clock speeds, various memory board and chip speed access, DMA channel efficiency and speed, all affect what your interleave might eventually wind up being. In the following paragraph, I am going to show you a quick and dirty way to quickly find the best interleave for your system. 1. Make all necessary connections to the hard drive to the Perstor controller as you would with any other controller. 2. Boot from a DOS equipped floppy drive and then switch to the Perstor diskette furnished with your PS-180 or PS-200 controller. Execute the PS2FMT low level formatting program. 3. Select the appropriate drive for formatting and select an interleave to begin your testing with. Record on a sheet of paper your interleave factor used for this step. 4. Allow the formatting program to run for 1 minute. Reboot the computer and execute the Coretest 2.7 analyzer program. Record your data transfer rate for the current interleave being used. 5. Repeat the procedure in steps 2, 3, and 4, above until you find where your maximum data transfer rate is achieved. At that point, do a clean boot, execute PS2FMT and low level the entire HD using the interleave that gave you the best transfer rate. 6. Please note that you should always use the manufacturers low level formatting program as opposed to the low level formatter furnished with Vfeature, Disk Manager, or SpeedStor. Would you believe 71MB on a ST-238 __________________________________ I have come up with a couple of configurations for the ST-225 and ST238 drives that have allowed a couple of purchasers of the Perstor Controller to break the 140MB barrier on just two Seagate drives. Here is the configuration that I have devised. Using a typical Seagate 20MB drive, you have 4 heads, 615 cylinders at your disposal. On a regular MFM controller you will get your regular 20MB of rotating memory. On an Omti 5527, WD1002-27X, DTC 5150CX, or Adaptec ACB-2070A RLL controller you should be able to format the drive out to about 32MB and change. With the Perstor PS-180 Controller, you can format this drive out to 38.13MB. Now, you ask, where does all that extra megabytes come from? By using the Perstor HD Compression software, that's how. The secret in getting the maximum benefit from the compression software is to set up a partition no bigger than 16MB to use the utility on. Here is a typical situation where you could get 54.72MB, assuming you needed a large boot partition, let's say in the neighborhood of 20MB. 1. Format the drive using PS2FMT. Run FDISK and choose 350 cylinders for the first partition. At this point, exit FDISK and run the DOS Format.com program to high level format the first partition. Format C: /S/V will high level format, place the operating system on the partition and prompt you for a volume label. After this, run chkdsk and see if you have about 22,220,800 bytes of storage on the first logical drive. 2. Now this leaves 265 cylinders unaccounted for. We are now going to get the Perstor PSE2FMT program going. When this program is executed, you will see a screen that looks just like FDISK. You are now going to create a second partition on the HD with this program. Just tell PSE2 that you wish to use the remaining 265 cylinders for the second partition. The partition will be created and high level formatted all in one step. It is then necessary that you install the perstor driver in your config.sys file with the appropriate device= statement. 3. Now what you will see when you run chkdsk on this second partition is a 33MB partition. Do not fret that it only show 16mb free. Let the driver do it's work. You will be able to put 33mb worth of data on the partition. The driver will take approximately 20K of RAM from your 640K. Well worth it to get this kind of increased storage upstairs. Now for scenario number two where you can get 71.2MB on the drive. 1. Do the low level format with PS2FMT. 2. Using FDISK, create a partition using only 85 cylinders. High level format this partition with the normal Format x /s/v where x is the drive letter to be formatted. 3. Using PSE2FMT, create 2 partitions of 265 cylinders each. This should give you 16.4MB of physical room on each of the two partitions. 4. When you get through with the PSE2 program, you should now have a drive with 5,396,480 bytes (5.2mb) on it in the first partition and two (2) partitions of 33MB each, for a total of 71.2MB. Don't ask me how it works, boss! It just does. The next bulletin in this series of informational files will be Perstor2.arc. Call Sparta PCBoard @ (201) 729-7056 to get the latest information on these fine controllers. Richard Driggers Sysop