Re: no hotplugging support (FIXME)

[Todd and Margo Chester <ToddAndMargo@verizon.net>]

Robert Hancock wrote:
> Todd and Margo Chester wrote:
>> Robert Hancock wrote:
>>> Todd and Margo Chester wrote:
>>>> Hi Jeff,
>>>>
>>>> I am having a nasty problem with hot swapping a removable (not
>>>> eSATA) drive I use for backup on several servers.  It is reported
>>>> over on
>>>> http://bugs.centos.org/view.php?id=3391
>>>>
>>>> Trying to help me find a work around to the problem at
>>>> http://www.centos.org/modules/newbb/viewtopic.php?topic_id=18608&start=0#forumpost68783 
>>>>
>>>> Alan posted your ata_piix.c code at
>>>> http://centos.toracat.org/ajb/tmp/toddandmargo/ata_piix.c
>>>> He pointed out
>>>>
>>>> 1483 /* no hotplugging support (FIXME) */
>>>> 1484 if (!in_module_init)
>>>> 1485 return -ENODEV;
>>>>
>>>> What do you mean by the comment in line 1483?  Is there some
>>>> know issue with hot swapping SATA drives?
>>>
>>> If you're using the ata_piix driver then it means your motherboard is 
>>> not in AHCI mode, so hotplugging is not supported by either the 
>>> driver or controller. You have to enable AHCI for SATA hotplug to 
>>> work on Intel controllers.
>>>
>>
>> Hi Robers,
>>
>>    As far as I can tell, ACHI is turned on on my motherboard.
>> I have tried all variation in bios (one of them turns /dev/sdb
>> into /dev/hda).   Does not mean ACHI is working right.
>>
>>    Do you know of any reason why my kernel
>> (CentOS 5.2: 2.6.18-92.1.22.el5) would not support
>> (bugs, etc.) hotplugging?
>>
>>    Also, do you know of a utility that I can use to
>> ask ACHI what is has for me (give me a report)?
>>
>> Many thanks,
>> -T
> 
> If the device is in AHCI mode then the ata_piix driver won't load for it 
> - at least it won't in current kernels, I can't say for sure that it 
> won't in the CentOS 5 version.. You do need to get it using the ahci 
> driver instead of ata_piix or hotplug definitely won't work.
> 
> You can try changing the boot initrd to try to load the AHCI driver 
> instead by changing the scsi_hostadapter entry in /etc/modprobe.conf to 
> be ahci instead of ata_piix, then rebuilding the initrd or reinstalling 
> the kernel RPM. However, if the BIOS isn't set up properly for AHCI mode 
> to work, you'll have to either boot up in rescue mode and fix it, or 
> boot up from a different kernel entry in grub.

Hi Robert,

    Thank you.  I take it there is no probe of the AHCI module.  Rats!

My /etc/modprobe.conf (BIOS: Enhanced SATA Mode):

alias scsi_hostadapter sata_sil
alias eth1 e1000e
alias scsi_hostadapter1 megaraid_mbox
alias scsi_hostadapter2 ata_piix
alias snd-card-0 snd-intel8x0
options snd-card-0 index=0
options snd-intel8x0 index=0
remove snd-intel8x0 { /usr/sbin/alsactl store 0 >/dev/null 2>&1 || : ; 
}; /sbin/modprobe -r --ignore-remove snd-intel8x0

While fooling around with my BIOS, trying to see what happens
in the various SATA modes, the one called "ACHI Compatibility mode"
changed my removable drive from /dev/sdb to /dev/hda.  ("mount /dev/hda"
still hangs for two minutes, then the kernel freezes.)

I am wondering if there is a clue here.  Does the ACHI module load
drives as /dev/sd* or /dev/hd*?

Many thanks,
-T

p.s., just of curiosity, what would the ACHI module look
like in my modprobe.conf?