CX300 attach question

There are a few things you'd have to check, but you may be able to connect another server (model doesn't really matter).

1. Does your current server use just 2 of the 4 fibre channel ports on the CX300? If so, the 2nd server can connect to the other 2 ports. If the current server is using all 4 ports already, could you (afford to) disconnect this server with 1 link from each storage processor to free up the ports to connect the other server?

2. In Navisphere, right click the CX300, go to Properties, select the software tab and look for the flare code version (if you're buying new enclosures they'll have to be DAE2P's (assuming you're going FC drives), which require a flare code of 02.19 as a minimum, but depending on the drives (size) you're buying you may even need a newer flare version). To upgrade the flare from below 19 to 19 or higher isn't considered customer-doable, so you may need to purchase the service to upgrade this on your system (here in the US you have the choice to have Dell do this over the phone and Internet (if you're at least on release 16), or come onsite (there is a difference in price and leadtime).

3. While on the software tab, verify you have the 60 drive option installed. I believe it should be there automatically with modern flare codes, but older flare codes didn't always have this.

4. Also while in the software tab, check to see if you have Accesslogix. If so, go to the access control tab and verify access control is enabled. If you don't have this software, and you're not planning to cluster the 2 servers (e.g. Microsoft Cluster Services, Red Hat GFS cluster, Oracle cluster, etc), you'll need to purchase this also when you're talking to your salesrep.

Note: Unless you're going to cluster (or are using a cluster aware filesystem like VMFS, OFS2, or GFS), 2 servers cannot share SAN disks (LUNs). If you do 'force' this, you'll run into filesystem and data corruption (may start as soon as a few seconds after the 2nd server can see the LUNs, or could take a few days (before you notice it), but it will happen. With linux you could opt to only mount as read-write on one server, and just read-only on the other, but the read-only server will not see any data changes on the lun till it unmounts the lun and then remounts it again.

Thanks for the good info. It looks like we're in good shape to connect a second server. 

Concerning your very last paragraph I do have another question.  Our short term plan would be to have the second server using separate LUN's and doing a separate job completely, which should be simple and safe enough..  But in the long run we may want something different, and in an MSDN article (http://msdn.microsoft.com/en-us/library/aa479364.aspx#scaloutsql_topic4 Figure 1) I was reading they show in the diagram having a number of sql servers all reading from the same database on a disk array and the database is set to 'read only' of course... So in that case wouldn't that require 2 different Windows servers to share SAN disks?  Wouldn't it be safe in that case if all the data is read only on the disk?  I just wanted to clarify since it sounded as if Windows was incapable of doing this from your last statement.

You'd have to check with Microsoft on how to implement that, as Windows cannot mount a disk as 'read-only' as such.

The EMC SAN cannot set the LUN to be read-only, but you might be able to change the security to where nobody (no users or system services) have write permission on the NTFS filesystem. This would be very tricky though, as 1 person making a mistake and trying to make the filesystem writable to do any kind of update to the data (write even just a single record to the database would require this), and you've opened an opportunity to corrupt the filesystem if more than 1 system is up and running and able to access that LUN (as permissions aren't done on a physical system level, but on a user account level).