[OpenIndiana-discuss] Opinions on LSI RAID vs. ZFS

[Joshua M. Clulow]

On 10 October 2013 00:18, Laurent Blume <laurent+oi at elanor.org> wrote:
> Solaris and descendants are not hot-swap OS's. If you want to replace a
> drive, you need to tell the system beforehand that you will remove a disk
> with cfgadm, and depending on your HBA/driver combination, tell it again
> after you put in a new disk with a combination of cfgadm/devfsadm.

This is emphatically false.  Though the pestilence of cfgadm(1M) and
the idea that device replacement is somehow advantageously manual had
persisted inside Sun's walls until its untimely demise, SunOS itself
is certainly capable of hot-plugging devices.

If you have a SAS controller attached via the mpt_sas driver, for
instance, you can absolutely expect hot plugged disks to go away and
return automatically.  If not, then you are experiencing bugs in the
system and should report them as such so that we can fix them.

SATA disks attached to SATA controllers supported through the sata
framework are something of a special case.  There is a tuneable that
prevents SATA hot plug from working, which is unfortunately enabled by
default -- again due to history and the misguided manual configuration
crowd.  You can enable it in /etc/system, though.  The variable in
question is "sata_auto_online", visible (with comment) here:

  http://src.illumos.org/source/xref/illumos-gate/usr/src/uts/common/io/sata/impl/sata.c#96

You can see our change (in Joyent's SmartOS) to enable it, here:

  https://github.com/joyent/smartos-live/commit/72e6c91


Cheers.

-- 
Joshua M. Clulow
UNIX Admin/Developer
http://blog.sysmgr.org