Direct Attached Storage with eight 146GB SAS 15k drives. With the RAID card we own if we create a RAID 5 partition for all or some of these drives we can let the RAID card set up virtual disks splitting up the RAID 5 space, e.g. if we have 438GB usable space we could have 4 virtual disks each 109GB; each for a storage group. With our RAID card if we set up a RAID 10 array we cannot set up multiple virtual disks. The RAID 10 array would present the entire space from an array. If we set up six drives in RAID 10 (3 for the data, 3 for the mirroring) we would need to use Windows Server 2008 (which we own for this machine) to partition the space to present it for the storage groups for Exchange. Each storage group would have 109GB. EHLO and elsewhere seems to advise letting the hardware (or NAS; which we do not own) partition the space. I am confused by LUN if we had a SAN the SAN OS might take a RAID 10 array and divide the usable space and present it as separate partitions (LUNS?). Is it silly to consider using Server 2008 to partition a RAID 10 array or should I stick with RAID 5 and let the RAID card set up virtual disks? Would it be better to obtain 450GB or 300GB 15k SAS drives (which would be possible in our organization) and give each storage group its own RAID 1 array? When we backup from a storage group, I assume it would be faster to pull from a Server 2008 created partition of a RAID 10 array than from aRAID 1 array. If we run eseutil or otherwise hammer a storage group in off hours, wouldnt a RAID 10 array be faster? Everything on EHLO and elsewhere points to RAID 10 but since we do not have a SAN if I use RAID 10 we must let Server 2008 partition that RAID 10 array into separate spaces for our storage groups. Is it acceptable to let Server 2008 partition the space presented by a RAID 10 array? We have the same issue for log files. I know RAID 10 is recommended and RAID 1 is OK. If we have six drives available (with another as a spare), and three storage groups, hence three sets of log files, (once again SAS 15k hard drives) would it be best to give each storage group its own RAID 1 array or have one big RAID 10 array and let Windows Server 2008 partition that space? Is it acceptable to consider RAID 10, letting Server 2008 partition the presented space for each set of log files? The log files would be on their own RAID array and their own RAID channel(separate from the storage group array). With all of the talk on Microsoft's web site about direct attached storage and Exchange 2007 but no examples of how to set up the partitions given the RAID cards sold by the top five server manufacturers and what "LUN" means for businesses with that type of hardware, anyone who provides some actual examples and useful information will be a hero to many of us.

I'll be honest, and admit I didn't read your whole post (long and big font!), but Storage recommendations for Exchange can be found here: http://technet.microsoft.com/en-us/library/bb124518.aspx If you don't feel like reading it you can also use the Exchange Storage Calculator which will give you your requirements based on your userbase. The latest version of the calculator also includes RAID levels and recommendations for such http://msexchangeteam.com/archive/2007/01/15/432207.aspx