On 2/02/10 06:52 PM, Moshe Vainer wrote:
I beileve to have seen the same issue. Mine was documented as:
http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6843555
Areca did issue a fixed firmware, but i can't say whether that indeed
was the end of it, since we didn't do a controlled disk mixing
experiment since then.
I did find it strange that this is needed, since zfs is supposed imho
to id the devices. However, I got an explanation from James McPherson
about how the disk identification works, and it seems to reasonably
explain why it will work with some controllers and not with others.
I will ask James's permission to publish parts of his e-mail here. Hope
he has no issue with that.
Here's what I sent to Moshe a few months back, in the context
of http://bugs.opensolaris.org/bugdatabase/view_bug.do?bug_id=6843555
(Invalid vdevs after adding drives in snv_111)
===========================================================
What ZFS looks for firstly is the device ID (devid), which is part
of the SCSI INQUIRY Page83 response.
I have just now requested that Areca ensure that this information
does _not_ wander around, but stays with the physical device.
If the Page83 information is not available, then the devid framework
falls back to using the Page80 information, and if *that* fails,
then it fakes a response based on the device's reported serial number.
If ZFS cannot open the device via devid, it falls back to looking
at the physical path.
If the devid does not wander, then there is no need to look at the
physical path to open the device, hence there is no problem for ZFS.
Assuming that Areca's fix does in fact resolve this wandering problem,
then there is no problem elsewhere.
===========================================================
James C. McPherson
--
Senior Kernel Software Engineer, Solaris
Sun Microsystems
http://blogs.sun.com/jmcp http://www.jmcp.homeunix.com/blog
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