Hi All,
I apologise that this question is coming from a user, but I believe the
readers here are the only ones I can trust for a reliable answer, I have
searched the Internet for many days during the last month for all
available information, and due to the nature of the problem, I cannot
tell whether any solution I write actually works properly.
The scenario: I have a ViPower hot-swap mobile rack for swapping IDE HDs
on the fly. I am assuming that this device properly disconnects the
hardware and that I am faced with a software problem. Our technical
staff tell me that they have 'tested' hot swapping under RedHat 7.3
(Kernel 2.4.18-3) and it 'works'. In other words, they unmounted,
swapped, and mounted a new disk and didn't observe data loss. I am sure
that they are mistaken that this is a reliable process, as I have read a
great deal about the hdparm program and its -R and -U switches. But
nothing that I can find explains exactly what is going on when hdparm is
called; the man page is dreadfully vague.
I would like to write a utility that works as follows:
To unmount:
unmount partitions
Use hdparm -U to unregister
Auto-remove lines in fstab referring to removable device (to avoid
marnings on bootup check)
To remount:
Use hdparm -R to register the new device
Auto-install lines in fstab relevant to removable device
mount partitions
My question: Given your knowledge of the innards of the kernel, does the
above seem like a sound way to create a useful IDE hot-swap utility? As
the simple unmount/remount strategy _seems_ to work, I am not confident
that just programming this up and trying it will necessarily reveal any
flaws, which is why I seek your advice.
Here are a few other factoids that may be relevant. This utility comes
with Windoze drivers to set up hot-swapping. I installed them and they
worked, but immediately Partition Magic started crashing Windoze
whenever it was run. This behaviour even continued after uninstallation
of the hot-swap drivers. Furthermore, at that point Linux started
producing lines like this in /var/log/messages:
Mar 26 13:35:44 Loris kernel: hdd: dma_intr: status=0x51 { DriveReady
SeekComplete Error }
Mar 26 13:35:44 Loris kernel: hdd: dma_intr: error=0x84 {
DriveStatusError BadCRC }
(the above repeated half dozen or so times, then:)
Mar 26 13:35:44 Loris kernel: ide1: reset: success
After that, things work. I am startled that a Windoze driver has left an
effect in the system that is felt by Linux. Everything looks OK in the
bios setup, but I am not an expert and may have missed something.
Again, I apologise for a user posting on a kernel list, but I have done
a lot of work looking for answers and I do believe this is the only
place where solid understanding of the underlying problem is to be found.
Many thanks for any insight.
--
Ron House house@usq.edu.au
http://www.sci.usq.edu.au/staff/house
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This archive was generated by hypermail 2b29 : Mon Mar 31 2003 - 22:00:22 EST