SUMMARY: mix 'n match disk drives?

From: Ed Arnold (
Date: Mon Mar 25 1991 - 10:49:51 CST

I recently inquired whether there are any "gotchas" in mixing drives
of different geometries on a xy451, xy7053, or isp80 disk controller.

The general consensus was that this usually works, but two potential
problem areas were identified:

1) If mixing drive types on a xy451, make sure the "magic cookie"
   drive_type is different for the disks you are formatting on
   each controller. Otherwise, you won't be able to get at all the
   drives on each controller, from the format program. (If you have
   to change drive_type, this forces a re-format because drive_type
   is stored on the disk.)
2) One correspondent mentioned that he has observed some SMD drives will
   interfere with other when cabled together on the same controller.
   He doesn't know why, but just knows he has definitely observed
   this happening, probably caused by certain manufacturers not
   observing proper grounding or terminating conventions on the control
   cable. However, he seemed sure drives from the same manufacturer
   don't have this problem.

These successes in mixing drives were reported:

1) Four correspondents either said, or implied, that they are mixing
   drives on a xy451.
2) Two correspondents said they were mixing 1.2G and 2.5G Sabre
   drives and/or using both 3MB/sec and 6MB/sec (dualhead) Sabre
   drives on a isp80 controller.
3) Three correspondents reported success in mixing drive types on
   a xy7053 controller. Two specifically mentioned mixing Hitachi
   DK815 and Sabre 9720-* drives.

Thanks to the following persons for taking the time to reply: (Daniel Strick) (Alexander Dupuy)
fwp1@Ra.MsState.Edu (Frank Peters) (Rand S. Huntzinger)
Sandy Napel <>
Alastair Young <>
"Manavendra K. Thakur" <>
"Anthony A. Datri" <>

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