Date: Wed, 9 Apr 2008 12:38:03 -0700 From: Josef Grosch <jgrosch@juniper.net> To: Damian McGuckin <damianm@esi.com.au> Cc: freebsd-scsi@freebsd.org Subject: Re: SAS Drive Numbering inside the MPT driver Message-ID: <20080409193803.GB48274@juniper.net> In-Reply-To: <Pine.LNX.4.64.0804091019540.9605@key0.esi.com.au> References: <Pine.LNX.4.64.0804071345420.18981@key0.esi.com.au> <20080407165601.GB34852@juniper.net> <Pine.LNX.4.64.0804091019540.9605@key0.esi.com.au>
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On Wed, Apr 09, 2008 at 10:23:07AM +1000, Damian McGuckin wrote: > On Mon, 7 Apr 2008, Josef Grosch wrote: > > > I really can't answer your question. We tried the LSI controller and had > > a couple of problems. I think this was one of them. We have settled on > > the Adaptec 3805 which is an 8 port controller. We are very happy with > > this controller. It's fast, stable and well supported in FreeBSD. > > With this, if you want to use it JBOD, don't you have to create fake RAID > volumes on each drive. Initially this is > > Drive0 Volume0 > Drive1 Volume1 > > etc. Does FreeBSD use the Volume numbers at all when assigning drive IDs > > /dev/da0 > /dev/da1 > .... > /dev/daN > > or does it work purely from the slot position? > > Many Thanks - Damian We have not used JBOD as such. We mostly use RAID 0, 1, 5, 10. I fooled around with JBOD with each disk being stand alone. The controller presented each disk as a separate device ie. da0, da1 ... daN. So, no, you do not have to RAID a disk if you want stand alone. I did this when testing ZFS on 7.0. The controller labels the disk with something the controller sees but the OS does not. I know this because I moved, these are hot swap units, a disk from one slot to another and the controller told me that the label did not match the slot number. I assume the controller relabeled the disk or more correctly updated it's internal map because it never complained again. That being said, the controller presents the OS with a device and hides the details from the OS. I have had a number of situations where I have 6 drives in a RAID 10 and had to move disks around from their original slot. The controller bitched once but the OS, FreeBSD 6.2, 6.3, 7.0 saw the RAID as one disk with one device. It never knew that the disks had been moved around. We at Juniper have a long history of using Adaptec controllers. I have about 200 servers using the 3805 and, except for outdated firmeware, have never had a problem with them. I think if you start using the 3805 it will be one less thing to think about and you can go back to putting out all the other fires you are fighting ;-) Josef -- FreeBSD 6.3 | Josef Grosch | You can't expect to wield supreme executive power jgrosch@juniper.net | just 'cause some watery tart threw a sword at you!
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