Qlogic fibre channel support questions

[Danny Braniss]

> 
> On Mon, 27 Feb 2006, Matthew Jacob wrote:
> 
> > Okay- let me ask why diskless booting doesn't work for you?
> 
>    Because NFS is slow.  A locally disk (or a SAN attached disk, which is 
> essentially the same to FreeBSD) is going to be faster than NFS, no matter what.

don't be too hasty with conclusions :-)
1- diskless: you can always boot diskless, then switch to 'real disk'
   in /etc/fstab:
	/dev/da0a	/	ufs	rw	1 1
    or what we do:
	/dev/da0b	none	swap	sw
	/dev/da0d	/var	ufs	rw	2 2
	/dev/da0h	/home	ufs	rw	2 2

   so you don't have to boot from the SAN, but after loading the kernel
   (via 'slow' NFS) it will use the SAN.

2- as to speed, it all depends, specially on how deep are your pockets.
   i've been running several 'benchmarks' latetly and disk speed is not
   everything.

   sample:
	host is a Sun Fire X4200 (dual dula core Opteron) with SAS disks
	OS is FreeBSD 6.1-PRERELEASE amd64.

	make buildworld:
	diskless: 	40m16.71s real 54m18.55s user 17m54.69s sys
		(using only 1 server*)
	nondiskless:	20m51.58s real 51m13.19s user 12m59.84s sys
	   "  but /usr/obj is iSCSI:
			28m23.29s real 52m17.27s user 14m23.06s sys
	   "  but /usr/src and /usr/obj is iSCSI:
			20m38.20s real 52m10.19s user 14m48.74s sys
	diskless but /usr/src and /usr/obj is iSCSI:
			20m22.66s real 50m56.14s user 13m8.20s sys

*: server in this case is a Xeon running in 64 mode but not very fast
   ethernet - em0 at 1gb but at about 50% efficiency.
   this server will 'make buildworld' in about 40 min. using the onboard
   LSILogic v3 MegaRAID RAID0.

[iSCSI target is a Network Appliance]

sorry for the noise,

	danny