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Disk Tips: Using ATA/IDE Drives with Novell NetWare Stan Simmons [75600,3240] Mar. 06, 1992 ATA/IDE Background The IDE (Intelligent Drive Electronics) interface originated when Compaq Computers talked Western Digital and Imprimis into developing a drive that had an ST-506 controller integrated into it. The drive was then connected to a simple interface circuit in the system. The ATA/IDE interface is really just an extension of the AT I/O bus. The hard drive controller circuitry is actually on the drive electronics board. By integrating the controller circuitry onto the drive's electronics, Western Digital eliminated an entire circuit board and some of the interface electronics. This added very little to the cost of the drive, and substantially decreased the cost of interfacing the drive to the system. The ATA/IDE adapter is very simple from a circuit viewpoint: a few buffers, address decoding, and a single 40-pin cable connecting the drive electronics to the system unit. After seeing the benefits of the IDE interface, other manufacturers began creating IDE drives and "paddle" boards. Paddle boards allow installation of IDE drives into systems that do not have an IDE connector on the system board. The first IDE drives were 5.25-inch Imprimis Wren drives. Later most ATA/IDE drive manufacturers switched to the 3.5-inch form factor. Many of the new 2.5-inch drives also have an ATA/IDE interface. In the early days of IDE development there was no official standard, and several manufacturers came up with implementations that were not compatible. This led a group of manufacturers to band together to create a common access method committee and to develop standards for this and other interfaces. The CAM Committee created the AT Attachment (ATA) interface in March 1989. The revised ATA proposal was submitted to the X3T9.2 ANSI group in November 1990 and is scheduled for processing sometime this year. ATA/IDE Interface ATA/IDE is similar to SCSI in that it is a logic-level interface rather than a device-level interface like ST-506 or ESDI. ST-506 and ESDI controllers must control all of the drive operations including moving the heads from track to track and selecting which head to read from. ATA/IDE drives perform these functions at the drive rather than at the controller. The ATA/IDE interface supports one or two drives on a 40-conductor daisy chain cable. The current ATA/IDE specification recommends a maximum cable length of 18 inches. Most manufacturers specify a maximum of 24 inches. I have used 36 inch cables with no trouble, but I do not recommend it. Long cables can pick up stray signals from the motherboard or other sources. In a two drive system, the primary drive is called the master, and the secondary is called the slave. Jumpers on the drives select which is master and which is slave. Some early IDE drives do not follow the current master- slave interface conventions. These older drives will usually not work as the slave on a two-drive system but in many cases will work as master. ATA/IDE Translation Most AT BIOSes are fairly limited in the drive-type selections that they have available. A few of the newer BIOSes have entries for RLL and ESDI drives, but I have not seen any that directly support many of the ATA/IDE drives. Some BIOSes provide a User Defined Drive type that will provide support for the unusual ATA/IDE drive parameters. One of the goals of ATA/IDE was to operate with existing AT BIOSes. Since few systems directly support the drives, the drives must make themselves look different than they really are. Many ATA/IDE drives have more than 1024 physical cylinders. DOS and early versions of NetWare do not recognize any cylinders above the lower 1024. Most ATA/IDE drives offer a translation mode to overcome this problem. Usually the drive will logically double the number of heads and halve the number of cylinders. Many of the newer ATA/IDE drives also employ Zone Bit Recording to increase the drive capacity. This recording method puts more sectors per track on the outer areas of the drive and decreases the number of sectors per track in two or more zones near the center of the drive. This type of configuration is impossible to specify with a standard AT BIOS, but since ATA/IDE drives are intelligent, they can fool the system by appearing as a standard AT drive. ATA/IDE drives vary in how they handle the logical-to-physical translation. Many only support fixed translation; these drives may be used only on the specified configuration. Most of the higher-end ATA/IDE drives offer variable translation and can use any entry in the BIOS table that does not exceed the total number of physical sectors on the drive. ATA/IDE Bad-Sector Remapping Many ATA/IDE drives have automatic bad-sector remapping. These drives have spare sectors that are reserved for future use. When the drive detects an error on a particular sector, the data is recovered and written to one of the spare sectors. The bad sector is then flagged as bad, and the new sector is placed in the drive's look-up table. The Future of ATA/IDE One of the optional ATA/IDE interface signal sets support Direct Memory Access (DMA) transfers. Currently most ATA/IDE drives only support the old-style programmed I/O data transfer. Back in the 808x days PI/O transfer was substantially faster than DMA. But with todays higher-speed processors and data buses, DMA can improve performance significantly. PI/O transfers require a lot of overhead from the system. The processor must first read the data from RAM then write it to the drive for each word transferred. DMA transfers occur one block (usually 64K) at a time using the DMA controller instead of the system processor. The ISA DMA will allow up to 333KB/s transfer, but EISA will allow significantly improved DMA capabilities. Type A EISA DMA will allow up to 2MB/s transfer; type B EISA DMA allows 4MB/s; and type C EISA Bus Master DMA will allow as much as 33MB/s transfer! ATA/IDE Drives and NetWare The IDE286.ZIP file from DL 3 (NetWare 2.X Specific) in the NOVLIB forum on CompuServe contains a NetWare v2.2 disk driver which makes it possible to use ATA/IDE type disk drives with file servers using the ATA/IDE interface. The IDE386.ZIP file from DL 4 (NetWare 3.X Specific) in NOVLIB contains a NetWare v3.11 disk driver. The new IDE disk drivers are very similar to the old Netware ISA disk drivers. The major difference is that the IDE driver does not get the drive description from a table. It gets drive descriptions directly from the disk drives at initialization time. Do not format ATA/IDE drives with any programs that will do a low-level format. On most ATA/IDE drives a low-level format will not harm anything, but some drives are less protective than others. You can destroy some ATA/IDE drives by formatting them. Low-end Seagate drives are particularly susceptible. For those of you who use mirroring under SFT, you will see a problem with IDE drives. If a mirrored pair crashes, the first thing the OS does (after retrying) is reset the controller. This initiates the diagnostics if the master drive is still running (if not, the OS will time-out and crash, since the slave can't do anything without the master); if the master is OK, it will timeout looking for the slave and the OS will crash. Duplexing requires an ATA/IDE controller that allows the use of an alternate IRQ and I/O address. NCL and UltraStor produce controllers that provide a variety of settings. Some controllers may give a stack overflow error when run on fast 80386 computers. The only cure that I have found is to use a different controller. DO NOT run Non-Dedicated on an IBM Model 35 or 40 machine. 1) Install the drive(s) and controller into your computer. 2) If you are running two ATA/IDE drives, you will need to refer to the drive manual to set one drive to master and one to slave. 3) If you plan to boot from the hard drive, run your setup program and set the drive type(s) to 1. Do not use a User Defined drive type with the NetWare IDE driver. User Defined drive types produce unpredictable results with IDE drives that do not provide full translation. 4) If you plan to boot from a floppy drive, run your setup program and set the drive type(s) to 0 or none. 5) Turn the power to your computer off then back on. 6) Do not use DOS 5.00 at any time during the setup of a NetWare 2.x server. DOS 5.00 is known to have several incompatibilities with the NetWare server utilities. DOS 5.00 works on 2.1x or higher workstations, but not on the server. NetWare 2.0a and ELS NetWare 2.1x Older versions of NetWare do not directly support ATA/IDE drives. Unless your system BIOS drive table has an exact match for a particular drive, you will need to use Disk Manager - N to patch the NetWare operating system. Disk Manager - N v3.12 or higher is available from OnTrack Computer Systems, 6321 Bury Drive, Eden Prairie, MN 55346. OnTrack can be reached at 800/752-1333 or 612/937-1107, fax 612/937-5815. Be sure to get the NetWare version of Disk Manager; the DOS version will NOT work. NetWare 286 2.15c Advanced and SFT Do NOT format the hard drives with COMPSURF, since this can wipe out the embedded bad-track info. 1) From DL 3 (NetWare 2.X Specific) on NOVLIB get the files LOADER.ZIP and IDE286.ZIP. 2) Unzip these files and copy the included drivers (LOADER.DAT, INSTOVL.OBJ, IDE.DSK, and IDE.OBJ) onto the appropriate working copies of the NetGen diskettes. 3) Run NETGEN and select the IDE Disk driver. Continue the generation as normal. 4) When presented with the NetWare Installation option on the NetGen menu (on the machine to be set up as the file server, after the NetWare Operating System file and Utilities Files are generated, linked, and configured) select the DEFAULT INSTALLATION option. 5) Create and Save the PARTITION TABLE. This will create a Non-DOS compatible partition which will not be limited to the original AT BIOS/DOS Compatible Partition limitation of 1024 cylinders. Exit back to the NETGEN Menu. 6) Select NetWare Installation and choose the CUSTOM INSTALLATION option. From here you can modify the VOLUME information as much as you desire, but do NOT choose the PARTITION TABLE option or you will flag the partition as DOS Compatible and you may have cylinder wrap problems. Cylinder Wrap is a condition where the disk driver or controller can't access the total capacity of the drive and performs a MODULA on requested cylinders or blocks above it's limitation. This effectively restarts the disk request at 0 compared to the high count and causes data to WRAP upon itself on the disk. For example, if the driver limits the capacity of the drive to 1024 cylinders and a write request comes in for cylinder 1227 then the driver will subtract 1024 from 1227 (the MODULA function) and re-submit the request to cylinder 203. If there was already data there... POOF. Once you've been hit with it the only fix is to reinitialize the drive and eliminate the limiting factor. ** DO NOT EVEN LOOK AT THE PARTITION INFORMATION! ** 7) Save the volume information you need, then select the option to load the OS and System and Public files. 8) Continue the Installation procedure and load all the disk files. NetWare 2.2 Do NOT format the hard drives with COMPSURF, since this can wipe out the embedded bad-track info. 1) From DL 3 (NetWare 2.X Specific) on NOVLIB get the file IDE286.ZIP. 2) Unzip this file and copy the included drivers (IDE.DSK and IDE.OBJ) onto the appropriate working copies of the Install diskettes. 3) Run INSTALL in the Advanced mode. 4) Select the IDE Disk driver. 5) Continue the generation as normal. 6) You may ignore the "Warning! Bad Block Table not accessed" message that may appear at system bootup. This is just a poorly worded informational message. The Bad Block Table is read when the network operating system is loaded. 7) If you wish not to see the warning message you can boot from floppy disk instead of the hard drive. The driver will support up to four ATA/IDE disk drives in a file server. This is possible by using addressable adapters. These adapters allow the user to configure the base I/O address and IRQ. Primary I/O address is at 1F0h and IRQ 14, second address at 170h. IRQs 11, 12, or 15 may be used with the second I/O address. ATA/IDE Drives and NetWare v3.x Because of an interaction between some ATA/IDE drive translation schemes and the IDE.DSK driver, I do not recommend that NetWare 3.x servers boot from a DOS partition on the ATA/IDE drive. I recommend that you set your drive type(s) to 0 or none and boot from floppy. The IDE driver will automatically get the correct parameters from the drive. Please note that the IDE driver will return a cylinder value that is two less than the actual cylinder count. NetWare 3.11 Do NOT format the hard drives with INSTALL.NLM, since this can wipe out the embedded bad-track info. 1) Install the drive(s) and controller into your computer. 2) If you are running two ATA/IDE drives on one adapter, you will need to refer to the drive manual to set one to master and one to slave. 3) If you plan to boot from the hard drive, run your setup program and set the drive type(s) to 1. 4) If you plan to boot from a floppy drive, run your setup program and set the drive type(s) to 0 or none. 5) From DL 4 (NetWare 3.X Specific) on NOVLIB get the file IDE386.ZIP. 6) Create a boot diskette with DOS, AUTOEXEC.BAT, SERVER.EXE, IDE.DSK, and INSTALL.NLM on it. 7) After you have started SERVER.EXE type "LOAD IDE.DSK INT=E PORT=1F0". If you are duplexing you will need to load the second, third, or fourth IDE driver with appropriate PORT and INT values. 8) Continue the installation as normal. The driver will support up to eight ATA/IDE disk drives in a file server. This is possible by using addressable adapters. These adapters allow the user to configure the base I/O address and IRQ. The primary I/O address is at 1F0h and IRQ 14; the second address is at 170h, the third at 1E8h, and the fourth at 168h. IRQs 10, 11, 12, and 15 may be used with the second, third, and fourth I/O addresses. ATA/IDE Questions Q. What settings will IDE.DSK and IDE.OBJ use? A. When using the NetWare 2.x IDE driver, the primary I/O address is at 1F0h and IRQ 14, the second address is at 170h. IRQs 11, 12, or 15 may be used with the second I/O address. When using the NetWare 3.x IDE driver, the primary I/O address is at 1F0h and IRQ 14; the second address is at 170h, the third at 1E8h, and the fourth at 168h. IRQs 10, 11, 12, and 15 may be used with the second, third, and fourth I/O addresses. Q. How does a DOS partition effect the IDE drivers? A. If your drive provides full translation a DOS partition will not cause any more problems than it will with MFM or ESDI drives. But, if your drive does not provide full translation then the drive will become confused when the system changes from DOS to NetWare. In some cases the system will merely hang, in others you will see various data integrity problems. Q. What adapters allow alternate settings? A. I have tested the NCL America models 536, 537, and 525 ATA/IDE adapters. They all allow alternate addressing of both the IRQ and I/O ports. The model 525 has two separate ATA/IDE channels on one board. This allows true duplexing on a single card. NCL America can be contacted at 408/734-1006. The address is 574 Weddell Drive Ste 4, Sunnyvale, CA 94089. The UltraStor US15FM is reported to allow alternate IRQ and I/O port addressing. I have been unable to obtain one of these boards for testing at this time. Q. Why is Mirroring not a good idea with ATA/IDE drives? A. For those of you who use mirroring under SFT, you will see a problem with IDE drives. If a mirrored pair crashes, the first thing the operating systems does (after retrying) is reset the controller. This initiates the diagnostics if the master drive is still running (if not, the OS will time-out and crash, since the slave can't do anything without the master); if the master is OK, it will timeout looking for the slave and the OS will crash. Q. Can ATA/IDE drives be used with other NetWare drivers? A. If the BIOS drive table has an EXACT match for the drive that you are installing then you can use the standard ATDISK/ISADISK NetWare drivers. If your drive table does not match then you may experience problems when Hot Fix begins to redirect new bad blocks. Q. What problems does DOS 5.00 cause? A. Absolutely do NOT use DOS 5.0 when running INSTALL, or as the DOS that you boot with prior to running NET$OS! It will not work and/or it will cause you major problems and grief. Stick with DOS 3.3 on the server, or when using server utilities such as INSTALL, VREPAIR, DISKED, COMPSURF, ZTEST. DOS 5.0 was not released when these products were tested, and so NO testing was done with 5.0. Post- release testing has shown MAJOR incompatibilities! Q. What is the difference between logical and physical geometry? A. Many ATA/IDE drives have more than 1024 physical cylinders. DOS and early versions of NetWare do not recognize any cylinders above the lower 1024. Most ATA/IDE drives offer a translation mode to overcome this problem. Usually the drive will logically double the number of heads and halve the number of cylinders. Q. Why don't some drives handle translation mode well? A. Some of the less expensive drives only offer one or two translation choices. You must match these choices to your BIOS table. Most of the more intelligent drives will translate any drive type that does not exceed the true number of blocks. Q. Why shouldn't Non-Dedicated mode be used with ATA/IDE drives? A. The NetWare 2.x IDE driver has some conflicts with the IBM PS/2 model 35 and 40 floppy drive system. Any "clone" systems that closely emulate those machines will have problems as well. Q. Should VERIFY be set to ON? A. Most of the newer ATA/IDE drives have Read-After-Write verification built in to the hardware. On these drives you will not need to have verify turned on. If you are using one of the less expensive low-end drives you may want to turn verify on for a little extra protection. Having verify turned on does cause a slight performance penalty in some systems. Q. How much RAM should I have in my server? A. The recommended RAM/memory requirement for NetWare v2.2 should be determined from the following formula: (.005 x MB disk storage) + 2MB base + 1MB if nondedicated + a minimum of 2MB if running VAPS. Note that the file server will run with less RAM than recommended, but you may not be able to cache all of your directories. Also, there may be a decrease in performance, especially with VAPs. The absolute minimum is 2.5MB; the recommended amount is based on the above formula. The minimum RAM needs for the NetWare 3.x are determined by the following formula: ((.023 * MB disk storage) / disk block size in k) + 4M + NLM's If a Name Space other than DOS is loaded then change the .023 to .032. This will get the server running, at which point you want to check the MONITOR NLM, Resource Utilization, % of RAM for CACHE BUFFERS should be above 65 percent for optimum performance. Round up to the next full megabyte for both formulas. Q. Under what conditions should I use Disk Manager - N with IDE drives? A. Disk Manager - N is needed if you are running an ELS version of NetWare or you are running a version of NetWare earlier than version 2.15 rev. c. Disk Manager - N is also an alternative if you must run NetWare in Non-Dedicated mode. Many thanks to the kind people at Seagate in Dallas, Conner in Dallas, Compaq in Houston, and NCL in Sunnyvale for their assistance with this project. Also, thanks to the SysOps of NetWire.