Re: SCA SCSI drives for Ultra 1

On Jan 16, 2009, at 9:59 AM, Gabriel J. Michael wrote:

I am considering getting some hard drives for my old Ultra 1 Enterprise. It originally had two 4 GB disks, but one has died, and Ebay has some good deals on 18, 36, and 74 GB drives.

My question is this - the Ultra 1 has an SCA SCSI backplane that can support two disks. I know that there are two versions of SCA, SCA-1 and SCA-2, but it's difficult to find information about them, so I am unsure what version the Ultra 1 has (the service manual doesn't say, either), whether they are backward compatible, etc. I don't want to buy a 74 GB disk only to find that it doesn't work in my system.

What the U1 has is 80 pin SCA. There's an ancient SCA standard with fewer pins but I have never seen any actual hardware, so virtually all SCA hardware you can buy these days has the 80 pin connector and should fit if the drive fits into the bay ( one's 1", the other's 1.5" high IIRC )

I also know (from the Wikipedia article) that there are "single-ended" and "low voltage differential" types of SCA - http://en.wikipedia.org/wiki/Single_Connector_Attachment - but not sure what difference, if any, that makes for me.

Nothing to do with SCA. the underlying bus is a 16bit, single-ended Fast SCSI bus in the U1E's case. Low voltage differential is required for Ultra2 Wide SCSI which allows up to 80MB/s transfer speed ( and faster standards like U160 and U320 as well ) but all those drives should work Just Fine(tm) on older controllers, at least down to fast SCSI-II ( it works the other way around as well since the SCSI controller will negotiate transfer speed with each drive separately, they'll usually settle for the highest speed supported by both ). The only exception is high voltage differential hardware - Sun made quite a few controllers like that but drives are hard to find - these are NOT compatible with single-ended or LVD buses.

So, you can have any kind of SCSI on an SCA connector.

Virtually any decent-sized SCA disk you can buy these days should work in your U1E. You may have to put the root partition into the 1st few gigabytes, I dimly remember some versions of the firmware having trouble reading past 8GB or so - no idea if that still applies to OBP3 used in Ultras.

PS - let me say how impressed I am with the hardware support of the sparc64 port! I originally put Debian on this machine, only to find that there is no Linux driver for the Sbus to PCMCIA bridge. So, I decided to install NetBSD. To be honest, it was painful at first (I think coming from stuff like Ubuntu has made me lazy!)

Oh sparc64 is one of the easier ones - some Apple OpenFirmware needs patches to boot from CDs or refuses to do so at all ( see beige G3s for some horrible examples of how not to write firmware ) while others lack support for the onboard video hardware in their firmware ( see /chaos/control and Platinum onboard video for example. No OF console support so you have to use a serial console or a PCI video card ) - Sun is pure sanity by comparison.

- there is no dvorak map in the generic sparc64 kernel, so I had to create my own.

Please post a patch so someone can commit it.

But following the very good documentation, I quickly had things up and running. I recompiled the kernel last night to include the nell pcmcia bridge driver, and a few other things, and this morning I am up and running with a pcmcia WiFi card!