Recommendations for servers running SATA drives

Miroslav Lachman 000.fbsd at
Mon Sep 29 13:42:56 UTC 2008

Jeremy Chadwick wrote:

> On Sat, Sep 27, 2008 at 03:16:11PM -0400, Charles Sprickman wrote:
>>On Fri, 26 Sep 2008, Jeremy Chadwick wrote:
> This also leads me a little off-topic -- when it comes to disk
> replacements, administrators want to be able to do this without taking
> the system down.  There are problems with this, but it often depends
> greatly on hardware and BIOS configuration.
> I've successfully done a hot-swap (hardware: SATA hot-swap backplane,
> AHCI in use, SATA2 disks), but it required me to issue "atacontrol
> detach" first (I am very curious to know what would've happened had I
> just yanked the disk).  Upon inserting the new disk, one has to be
> *very* careful about the order of atacontrol commands given -- there
> are cases where "attach" will cause the system to panic or SATA bus to
> lock up, but it seems to depend upon what commands were executed
> previously (such as "reinit").
> Sorry if this is off-topic, but I wanted to mention it.

Hot-swapping is totally upredictable on FreeBSD (from my experiences). I 
tried it many times on Asus 1U servers and on Sun Fire X2100 / X2100 M2 
with FreeBSD 6.2 and 7.0 (both i386). It sometimes panics on atacontrol 
detach, but never panics if disk was marked as failed by gmirror and 
detached by system it-self, then just removed from running machine. It 
sometimes panics immediately after the re-insertion of disk, sometimes 
after atacontrol attach. Sometimes it detects and attach disk without my 
intervention, so I can easily insert the disk in to gmirror.
Then I stopped playing with hot-swapping and now always do power off 
before disk swapping.

Miroslav Lachman

More information about the freebsd-stable mailing list