Recommendations for servers running SATA drives [hot-swap]

[Miroslav Lachman]

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

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.

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

Miroslav Lachman
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    2 users    Load  1.00  1.00  0.99                  Oct 17 00:25

Mem:KB    REAL            VIRTUAL                       VN PAGER   SWAP PAGER
        Tot   Share      Tot    Share    Free           in   out     in   out
Act   40032    6212   118412     9352  509928  count
All   70200    7884  4370000    16700          pages
Proc:                                                            Interrupts
  r   p   d   s   w   Csw  Trp  Sys  Int  Sof  Flt        cow    197k total
          3  45      387k    6   75 193k  187             zfod        ohci0 21
                                                          ozfod       ehci0 22
 0.7%Sys  45.9%Intr  0.0%User  0.0%Nice 53.4%Idle        %ozfod  193k atapci1 23
|    |    |    |    |    |    |    |    |    |    |       daefr  2001 cpu0: time
+++++++++++++++++++++++                                   prcfr     1 bge1 273
                                        10 dtbuf          totfr  2001 cpu1: time
Namei     Name-cache   Dir-cache     68955 desvn          react
   Calls    hits   %    hits   %     58041 numvn          pdwak
                                     17234 frevn          pdpgs
                                                          intrn
Disks   ad4   ad6                                  191128 wire
KB/t   0.00  0.00                                   59664 act
tps       0     0                                  242588 inact
MB/s   0.00  0.00                                   46108 cache
%busy     0     0                                  463820 free
                                                   113488 buf