Firsthand knowledge and experience as a Seagate Partner discussing this with several Seagate support technicians: Most SCSI disc drives support spin down, but not all. For spin down to work, there has to be several things. 1- the system must have software support to tell the drive when to spin down (this may include or already be included in firmware on the SCSI drive and/or controller). 2- the system has to properly see the drive. On many instances, I have seen systems that never spin the drive down until powered off because the drive is not seen as a proper drive (IE: using a drive larger than what can be seen by SCSI BIOS, or as some know, using a drive as a 'dumb' replacement for an older one that failed (see huge full-height Seagate SCSI drives for older systems - Dave Woyciesjes knows about this as I personally know of him implementing such a thing)). 3- there must be a trigger to cause the spin down (time out delay, overheat, software command during diagnostics, etc.). I hope that helps a bit. Oh, and almost forgot: I do know of some SCSI drives that were never made with the spin down command (which I know is odd since I believe it is part of the SCSI protocol, etc.) - Maxtor made a small line with them and talking to Seagate, they had at least 2 of them that lacked it. There are most likely a few from other brands, but those are the ones I know of as is. One last thing: for spin down, you don't need to have SCA. It can be just about any SCSI interface or version from what I've been told. What you are thinking about is spin down linked with hot swap, which is something else (SCA only). This is because SCA has the power and SCSI all going through one interface and circuit controlled. Other interfaces lack that and will cause power fluctuations and SCSI errors that in many cases will lock a system (a few older systems would sometimes forgive you and let the disturbance slide without locking up). Spin down was included in the specs because of power saving features. The drive would still draw a little power and come back if an init or access (read/write, etc.) command was passed. The spin down with SCA drives allows with firmware and circuitry to make it ok to pull the drive with that small amount of voltage left and automatically adjust for the change in number of drives, etc. Hope that helps. If need be, I can email you links to several references on this topic, including white papers, tech specs for whatever drives you get and software. Let me know how it goes. -John Boffemmyer IV At 07:10 AM 4/28/2004, you wrote: ---------------------------------------- Founder, Lead Writer, Tech Analyst and Web Designer Boff-Net Technologies http://boff-net.dhs.org/index.html ---------------------------------------