Recommendations for servers running SATA drives [hot-swap]

[Jeremy Chadwick]

On Fri, Oct 17, 2008 at 01:50:38PM +0200, Miroslav Lachman wrote:
> Jeremy Chadwick wrote:
>> On Thu, Oct 16, 2008 at 09:30:20PM +0200, Miroslav Lachman wrote:
>>
>>> Today I was replacing disk in one Sun Fire X2100 M2 so I tried   
>>> hot-swapping. It was as you said: atacontrol detach ata3, replace the 
>>>  HDD, atacontrol attach ata3 and new disk is in the system. I tried 
>>> it 3  times to be sure that it was not coincidence - no panic was 
>>> produced ;o)
>>> So in this case, hot-swapping on Sun Fire X2100 M2 with FreeBSD 7.0 
>>> i386  works.
>>
>>
>> That's excellent news.  So it seems possibly the problem I was seeing
>> was with "reinit" causing some sort of chaos.  I'll have to check things
>> on my testbox here at home to see how I caused the panic last time.
>>
>> Thanks for providing feedback, as usual!  :-)
>
> Unfortunately there is one problem - I see a lot of interrupts after  
> disk swapping (about 193k of atapci1)
>
> Interrupts
> 197k total
>      ohci0 21
>      ehci0 22
> 193k atapci1 23
> 2001 cpu0: time
>    1 bge1 273
> 2001 cpu1: time

Okay, so it looks like the interrupt rate on atapci1 after swapping is
going crazy.  What you're showing there looks like heavily modified
vmstat -i output.

> Full output of systat -vm 2 is attached.
>
> It is shown in top as 50% interrupt (CPU state) and load 1 until I  
> rebooted the machine (I can provide MRTG graphs). The system was not in  
> production load, but almost idle. (I will put it in production tomorrow).
> After reboot, everything is OK.

And this box is running the ATA patch Andrey provided, yes?

> Can somebody test hot-swapping with SATA drives and confirm this  
> behavior? (I can't test it now, because machine is in datacenter)

I can test it on my P4SCE box.

I'll check the interrupt rates after each step of the hot-swap to see
if/when the problem starts.

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |