I would prefer SCSI drives for VPS nodes or DB machines, but otherwise for hosting in general, SATA will be more than enough to get the job done, and it's cheap.

SATA = Cheap SCSI = Good :-)

I perfer SCSI. Reliable and fast. SATA is a decent second choice though if you are looking for a more cost effective solution.

SCSI gives a good RPM around 15-20000 thousand comparing with 8000 of SATA . The speed and reliability of SCSI is more then SATA although the price is a down side when comparing the two . I would go for SCSI if have that much money for performance .

I would choose SCSI my self although the hosting company I worked for had a lot of SATA.

When you select SCSI make sure that it is 15k RAM instead of the more common 10k RPM. MySQL.com especially recommend SCSI with higher RPM for better preformace.

SCSI is dead, buy SAS for super high performance. Expect 4x the price of SATA.

SAS is preferable for databases since writes are performed to the disk in a safer manner than SATA (cache on the drive is smarter and reports written only if it can be safely written with a power loss).

That said, SATA with a 3ware raid controller with an installed battery backup is probably just as reliable in the real world.

In enterprise environments, SAS with battery backups on the controllers is what gets used today. But thats major $$$.

For a 'forum' you just want high performance, losing one post every 100 years won't make a difference. So just use SATA raid 5 with a 3ware controller. Read performance is excellent on Raid 5. Writing is slower but a forum does mostly reads.

I would go for good quality sata with better speeds as i can get more speed for lesser price . and also set up RAID levels for a lower price .