Throughout this Info Guide the following typefaces have special meaning:

This Info Guide makes the following assumptions:

• That the Mylex card and the hot-plug backplane have been installed in the FT//ex. For guidance with these tasks review the installation documentation supplied with them. This guide will however, detail the EISA Configuration Utility disk settings and power supply related issues.
  
  
• That a single array of drives configured as a RAID 5 array is to be installed. This type of array provides drive redundancy without the need for duplicating the entire array of drives with a mirrored array, and provides a disk performance increase through striping. RAID 5 is the default configuration for the Mylex card and requires at least 3 drives. Assuming all drives are of the same size, an amount of storage capacity equal to that of one drive in the array is lost, it being used throughout the array to hold parity information for rebuilding data should a drive fail. So, for an array of 5 drives each of 1Gb, the size of the system drive (as Mylex refer to it) that the Mylex card offers the host is 4Gb.
  
  
• That SCO Unix 3.2v4.2 is to be installed from a SCSI tape set to ID 2 connected to the on-board AIC-7770. An installation from CD-ROM connected similarly should be similar, but note that the CD-ROM must be set to ID 5, this being an SCO feature.

Only Apricot supported drives for the FT//ex with Mylex card should be used. At the time of writing these being the Quantum 525Mb, IBM 1Gb (Spitfire), and Seagate 2Gb (Barracuda). Supported drives in the future will include the IBM Starfire 1, 2, and 5Gb.

Follow these notes in the order written to start from an unconfigured system through to SCO Unix installed onto a RAID 5 drive array.

(5th July 1994)

FT//ex configuration

Mylex

The EISA Configuration Utility (ECU) settings for the Mylex card are as follows:

The strap settings for the card should be correct but the following should be checked:

AIC-7770

Disable the AIC-7770 BIOS from within the Advanced Setup menu of the FT//ex (<cntrl><alt><esc> during DOS boot) by setting SCSI I/O ROM Mapping to Disabled. The ECU settings are as follows, of note here is the interrupt setting which should remain on its default of IRQ 11 for an SCO Unix installation:

Note that additional SCSI devices such as a tape (set to ID 2) and CD-ROM (set to ID 5) should be attached to the AIC-7770, not to the Mylex card.

Power supply cabling

An instance has been seen where upon adding a sixth IBM 1Gb drive to an installation consisting of a five drive array plus CD-ROM and tape drive, two of the existing drives powered down. The power supply is able to power such a configuration, but the power supply loom connector locations should be checked to safeguard against such possibilities.

Apart from the power supply wiring that connects to the mother board, there are three distinct groups of wires for connecting drives, fans, etc. Two of these groups of wires from the power supply are arranged in two 6 way rectangular connectors. Connect these to the 3 connectors on the rear of the hot-plug backplane via standard drive power connectors on the daisy-chain wiring that is plugged into these 6 way connectors. One group will be connected via 2 drive power connectors that are very close together on their wiring run, and the other should be connected via the first drive power connector on its wiring run. Use the third group of wires which consists of 4 wires (2 black, 1 red, 1 blue) to connect to the CD-ROM and tape drive.

Label drive trays

Label the drive trays that are fitted with hard disks with their SCSI ID. This will allow location of a drive when action is required in response to messages from the Mylex firmware/BIOS or the Mylex software utilities.

Define a system drive

Before the SCO Unix installation can be started the drive array has to be configured to present what Mylex call a system drive to the system. This is done by using the Mylex DOS utility daccf in the \daccfg directory of the DOS utilities disk supplied with the card. This will be described in this section.

Mylex BIOS does not recognise a system drive

When the system boots up observe the messages from the Mylex BIOS and firmware. Once the hardware is installed and configured as in the previous sections the system will probably show the following messages:

The above message will also occur for a configured RAID system if the machine is powered up with a hard disk removed from the backplane, or a drive does not spin-up in time.

Formatting drives

If you wish, new drives can be formatted by the Mylex card. Do this by running the daccf utility. Once it has scanned for the installed drives select from the main menu, then select Format Drive from the Tools menu. Use the arrow keys to highlight the drive to format from the pictorial display of drives that are ready. Mylex describe drives that are seen but not configured as part of a system pack as ready - the pictorial labels these drives RDY.

Creating RAID 5 array - the default for at least 3 drives

Select Automatic Configuration from the Main Menu to configure a RAID 5 array. You will be asked Do you want to have the Write Cache enabled? Select Yes to this question. Selecting No means that the Mylex card acknowledges a write operation only after it has received confirmation of a write from the drives in the array in the same way as a non-caching disk controller. Selecting Yes means that the card gives an acknowledgement as soon as it has written the data to its cache, updating the drive at some later time.

Select Initialize System Drive from the Main Menu. Select Sys Drv 0 followed by Start and then select Yes to proceed. Initialisation takes a considerable time.

At this point a system drive of 4Gb will exist for a configuration consisting of five 1Gb drives as an example. More complex arrangements can be configured by splitting a system pack into multiple system drives or by installing multiple physical packs that contain multiple system packs and system drives. However, the Mylex User's Manual should be studied for a description of such configurations and terminology.

The largest array possible using a single Mylex card, which is the only Apricot supported configuration, is seven drives. Assuming a RAID 5 configuration without a standby drive using 1Gb drives, a system drive of 6Gb would be available.

For interest, select View / Update Configuration followed by Define Pack or Define System Drive to view the geometry of the configuration. Note that the Define Pack option will show the physical disks as online (marked as ONL in the pictorial view of the hard disks). Selecting Tools from the main menu will also show the status of all the physical disks connected to the Mylex card, this is much quicker than the View / Update Configuration option and is best for merely viewing the status of the drives.

On boot-up the Mylex firmware and BIOS should now give the following messages:

daccf cannot find any drives

The Mylex firmware and BIOS message may indicate that one or more drives are not responding. This will almost certainly be because the EISA Configuration Utility option DAC960 disk spin-up options will be set to Disabled:disks spin on power-up. Ensure that it is set to 1 disk started every 6 secs as shown in the section entitled "FT//ex configuration" earlier in this guide.

If the option is set incorrectly as above you may need to power the system off and leave for about 30 seconds before powering up again. This action may have to be repeated several times to get the drives recognised.

If the ECU option referred to above is set correctly and drives are still not recognised, review the sub-section later in these notes entitled "DAC960 Toolkit" in the "Mylex utilities" section. It may be that the card's NVRAM setup needs forcing to recognise the drives.

Creating configurations other than a single RAID5 array

For drive configurations other than the default described in the above sub-section you are advised to read the Mylex User's Manual, in particular the chapter describing the use of the daccf utility.

Configuring a standby drive

Another configuration which is similar to the default RAID 5 configuration is one where a RAID 5 array is defined as a system drive and another disk is defined as a standby drive. In such a configuration, should a drive fail within the RAID 5 array the array becomes critical and automatically brings the standby drive into the array and commences a rebuild making it a redundant array once more. Refer to the daccf chapter of the manual.

Installing SCO Unix

In addition to the SCO distribution floppies and tape, BTLD driver disks are required for the on-board Adaptec AIC-7770 and the Mylex DAC960E. These disks are labelled:

Boot from the SCO N1 floppy as normal and at the Boot: prompt enter link. Enter the following when asked what drivers are to be linked in:

Continue with a normal installation. You will be asked to insert the volumes that contain these drivers on two separate occasions during the installation.

The installation will default to a SCSI tape on ID 2 connected to the AIC-7770 (arad driver). If a CD-ROM is being used the installation will say that the CD-ROM is to be on SCSI ID 5, as mentioned in the Introduction section.

Once SCO Unix is installed check the /etc/conf/cf.d/mscsi file for a SCSI tape entry. If not present re-create the SCSI tape with the mkdev tape command in the normal manner.

Mylex utilities

The five utilities are as follows:

Installation of the utilities

The utilities are supplied on a tar format floppy. Before installing them you are directed by the Mylex manual to move /bin/sync to /bin/sync.old, as the sync binary is replaced by the Mylex version which carries out the additional task of flushing the disk cache on the card to the drives.

Use the following commands:

Suggested modifications
Once the utilities are installed it is suggested that the following modifications be made.

• The monitor utility that logs failures of drives and other important messages from the Mylex card (dacmon1d) should be running at all times. Add an entry such as the one below to the /etc/rc2.d/S88USRDEFINE to ensure this:
  

  #### Mylex DAC960E status monitor
  if [ -x /bin/dacmon1d ]
  then
  

  /bin/dacmon1d &
  echo "Mylex DAC960E status monitor\n"

  else

  echo "Mylex DAC960E status monitor not running - RECTIFY"

  fi
  ####

   

• The monitor utility dacmon1d logs its messages to the file /usr/dac960/dac01log for the first Mylex card. The Mylex manual refers to the log file dac02log, this being the logfile for a second card if configured. However, as stated earlier, the standard Apricot supported configuration is for a single card only. Messages are also sent to the console, but are not send to the /usr/adm/messages file.
  
  It is suggested therefore that a script is added that is run by cron at a frequent interval such as every hour that checks the log file for messages. It should do such things as update the /usr/adm/messages file and mail the system administrator. Contact Unix Support for such a script.

Using the utilities

DAC960 Sysadmin Shell
The main utility that will be used is the menu based DAC960 Sysadmin Shell (/bin/dac960sh). Refer to the Mylex User's Manual for a full description. Briefly though it is used for the following tasks:

• Selecting the Mylex card to be accessed. However, the standard Apricot supported configuration is a single Mylex card so it will be selected automatically.
  
  
• Viewing the status of the physical drives. Select Rebuild or Change Device and check that no drives are marked DD which indicates that they are dead. If the DAC960sh has been left running on screen then return to its main menu and re-select the option desired to ensure an up-to-date display of disk status. A recent dead drive may not show as DD if the Rebuild or Change Device screen has been left on display.
  
  
• Changing a faulty drive. When you want to hot-swap a defective drive select the Change Device option. Then select the drive to be replaced and the SCSI bus will be halted. Replace the drive with an identical type set for the same SCSI ID and once it has spun-up enter resume to restart the SCSI bus. The drive array must then be rebuilt, see below.
  
  
• Rebuilding the drive array. Once a faulty drive has been replaced as above, select the Rebuild option. Then select the drive shown as dead to be rebuilt. System performance will suffer whilst the array is rebuilding, but normal work of users continues.
  
  
• Running the DAC960 Toolkit. The toolkit utility can be run from the command line as /bin/dac960tk, however it can also be run by selecting DAC960 Toolkit from the main menu. See below for its likely uses.

Recovering from a drive failure
The system administrator will be informed of a drive failure by entries in the log file /usr/dac960/dac01log and other means (see "suggested modifications" in the "Mylex utilities" section earlier in this guide).

To recover from such a failure the following steps should be carried out in order. Refer to the previous sub-section entitled "DAC960 Sysadmin Shell":

1. Obtain a replacement drive of an identical type. Set it to the same SCSI ID of the failed drive.
   
   
2. There will probably be a spare drive tray available in the system, so you may choose to use this to mount the new drive ahead of removing the faulty drive. Label this tray with the SCSI ID of the new drive and remove the labelling from the tray at present containing the faulty drive.
   
   
3. Hot-swap the faulty drive by selecting the Change Device option. This action will halt the SCSI bus to eliminate any glitches produced when hot-swapping the drive from causing a problem.
   
   
4. Rebuild the drive array by selecting the Rebuild option.

DAC960 Toolkit
Use of the toolkit will not usually be required, and its use without care "could incur catastrophic effects", to quote the Mylex User's Manual. The toolkit can also be run as a DOS utility from the DOS utility floppy supplied with the card. For a full understanding of the toolkit refer to the Mylex manual where the DOS utility description covers the Unix version also. Briefly, the most likely uses of the toolkit are as follows (given below are the option numbers as shown in the tookit main menu):

• 4. Make Standby.
  This option is used when you have added a disk to an existing configuration and want to configure it as a standby drive. This then becomes a disk that the card uses to automatically replace a failed disk. A standby drive cannot be added to an existing configuration with the DAC960 Sysadmin Shell.
  
  
• 7. Set Device State and 3. Start Device.
  There should never be a need to use these options under the Unix version of the toolkit. Use these two options in the above order when first installing the system. You are only likely to need to use them from the DOS based toolkit to force the state of the attached disks as stored in the Mylex card's NVRAM. Use them as below if the Mylex DOS configuration utility (\daccfg\daccf.exe) does not recognise the disks. Refer back to the earlier section entitled "Configure a system drive with daccf" if necessary.
  
  From the toolkit main menu enter the following to force the state of SCSI ID 3:
  
  

  7	-	this to select the Set Device State option.
  0	-	this to select the SCSI channel (always 0 on Apricot supplied single SCSI channel Mylex cards).
  3	-	this to select SCSI ID 3
  3	-	this to select the Start Device option.
  0	-	this to select SCSI channel 0.
  3	-	this to select SCSI ID 3.

  Use the above sequence for each SCSI ID of the disks attached to the card.

Emergency floppies

There is a potential risk of an inexperienced user damaging the data held on the array by using the Mylex toolkit utilities. For this reason alone it is desirable to make an emergency boot set of floppies and a full root filesystem backup using cpio. With the emergency floppies and the cpio backup tape the root filesystem can be restored onto a re-created system drive.

The use of emergency floppies to prepare a drive and then restore a root filesystem cpio tape is covered fully in Info Guide UNX003.

Creating the floppies

If emergency floppies are created in the normal way a Unix Panic may be encountered when booting from such floppies. For this reason we advise using the following procedure to make and then use the emergency floppies:

1. Make a boot floppy and root filesystem floppy in the normal manner by entering mkdev fd.
   
   
2. You now need to replace the kernel on the boot floppy with one without the Mylex driver. Do the following:
   
   
   • Edit the files /etc/conf/sdevice.d/dac1 and dac2 on the hard disk, changing the Y to N. Re-link the kernel, but answer N to the question asking if this is to be the booting kernel.
     
     
   • Mount the boot floppy and copy this kernel to it by entering:
     
     #mount /dev/fd0 /mnt
     #cp /etc/conf/cf.d/unix /mnt
     
     
   • Once the replacement kernel is copied to the boot floppy edit the dac1 and dac2 files back to Y.
     
   • Unmount the boot floppy by entering umount /dev/fd0.

    

3. The Mylex utilities can be copied to the emergency floppies so that there is no need to reboot and use the DOS based versions. Do the following:
   
   
   • Mount the emergency root floppy on /mnt and create the directory /mnt/usr/lib/terminfo/a and copy the file ansi from the hard disk to it by entering:
     
     #mount /dev/fd0 /mnt
     #mkdir /mnt/usr/lib/terminfo/a
     #cp /usr/lib/terminfo/a/ansi /mnt/usr/lib/terminfo/a
     
     
   • Add the entries TERM=ansi and export TERM to the root floppy’s .profile file (/mnt/.profile).
     
     
   • Copy the files /bin/dac960sh, /bin/dac960tk, and /bin/dacmon1d to the bin directory of the root floppy by entering:
     
     #cp /bin/dac960sh /mnt/bin
     #cp /bin/dac960tk /mnt/bin
     #cp /bin/dacmon1d /mnt/bin

Using the floppies

To boot from the emergency floppies the Mylex BTLD floppy is also required. If necessary, refer to Info Guide UNX003 for a full description of using emergency floppies and a cpio tape to restore the root filesystem onto a blank hard drive. The procedure in this case though is as follows:

1. Boot from the emergency boot floppy and at the Boot prompt enter link.
   
   
2. When asked for the name of the packages to link enter dac960 and insert the Mylex BTLD floppy when requested.
   
   
3. Insert the emergency root floppy when asked for the root filesystem floppy.
   
   
4. From this point on the use of the emergency floppies is much the same as any other system. The steps required to re-create a bootable root filesystem on the system drive are as follows (refer to Info Guide UNX003 for more detail):
   
   
   • Use fdisk to create a Unix partition. This will probably be the Use entire disk for Unix option.
     
     
   • Use divvy to divide the partition up into Unix filesystems and create a swap space.
     
     
   • Create the boot blocks and master boot block to make the partition bootable.
     
     
   • Check the root filesystem with fsck.
     
     
   • Mount the root filesystem and restore the root filesystem cpio backup tape.

Note that Mylex system drives do not appear to SCO Unix as SCSI drives or ST506 drives. Therefore the current Unix monitor u386mon will not display any drive utilisation statistics for them. However, do not attempt to create a bad track table with the badtrk command as is usual for ST506/IDE drives. The Mylex controller manages media flaws independently of the host operating system.