Mirroring with DiskSuite 4.2 - Summary

From: Eric Watson (ewatson@law.harvard.edu)
Date: Wed Jun 07 2000 - 10:14:29 CDT

Original question:

"Can anyone think of why it would be a bad idea to mirror the internal IDE
hard drive on an Ultra 10 to an external SCSI drive?"

Thanks to those who responded. There were two responses:

1. "It won't work because of different disk geometries." I don't think
this is true as all you are doing is mirroring slice to slice and as long as
the mirror slice is bigger it should work. I'll find out!

2. "If the IDE runs slower than SCSI, then the SCSI will be waiting for the
IDE on every write. The read can be configured to one of several options to
specify preference which disk is used - so you can lean toward the faster
disk for reading." Good one, I'll bet this is true. Given the nature of
the machine in question and what it's used for this shouldn't be a problem
for us.

Also, on a related subject, I had some questions on mirroring before and the
question arose as to whether or not you need to run install boot on a mirror
drive to make it bootable on a Sparc. The Answerbook documentation says you
must do this on a x86 but doesn't mention Sparcs. According to Sun the
mirror drive on the Sparc is bootable and installboot is NOT necessary.

My problem with testing this was that at the OK prompt I was putting in a
full path with a leading "/devices". If you drop the "/devices" it should
boot from the mirror drive. I haven't tested this yet (it's a production
machine) but I will at some convenient point in the future.


Eric Watson
Sr. Systems Administrator
Harvard Law School

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