I need to setup RHEL 6.5 64 bit on a setup where i have 2 app servers connected to a SAN. The servers are HP DL380 G8 and connects to a HP SAN P2000 G3 using FC. The servers connects directly from the HBA to the SAN (no SAN switch). the 2 servers works in active/standby mode, so only one server will read/write to the SAN at a time. I require a basic setup where the /var directory (containing the database) will sit on the SAN. And all other directories on the local drives of the server. I will also be using device mapper and multipathing for failover between the servers. Questions are:
1. What file system should be installed on the SAN? can i use ext4 (as the local drives) or there is a specific file system for SAN?
2. When i install the RHEL OS, there is an option which says 'specialized storage devices'. so i need to select that option right?
3. I also read about shared file system for SAN, can it be used in my setup here? If yes, then i don't need device mapper and multipathing?


Thakn you.
Navin

1. You use whatever file system on the SAN drive as you'd like. SAN is just another disk, so if you want to use EXT4, then feel free.
2. Maybe, maybe not. You might just be able to perform a standard load, and the installer may pick up your HBA as just another SCSI disk.
3. Which shared file system? There are many options.

Since you're using RHEL with HP hardware, that means you are paying for support from both Red Hat and HP...you really should contact them for assistance, and they can probably walk you through what you need to know. That's why you pay for support.

Use of a SAN does not typically require any special filesystem as it is just presenting storage much like you'd see from internal drives on the system itself. Here we've used vxfs (Veritas Filesystem), ext3, ext4 and Windows native filesystems all on the same disk arrays (from EMC and Hitachi).

While some things like MySQL might default to having database under /var you can and probably should modify that to be somewhere else (e.g. /database).

Even if you have your data subdirectory under /var you might want to consider having /var itself on the local disks and only make the data subdirectory on the SAN (e.g. /var/mqysql/data). Much of what is in /var is required during boot and you're not doing yourself any favors by putting all of /var on SAN if you're not also putting your /boot and / (root) there.

Typically during installation we do NOT configure the SAN storage - we only use the internal drives then configure the SAN storage after the fact. (Typically in different filesystems as noted above and usually in separate LVM Volume Groups to avoid mixing the internal and external storagge in a single VG.)

We've not done the direct to disk array setup for storage like you're attempting so I'm not sure what other considerations you might need to consider. If you have at least 2 fibre ports from each host to the disk array you do want to use multipath and insure whatever storage you configure (VG, ASM, partition) for your database is pointing to the multipath device rather than directly to one of the /dev/sd* devices.