Nov18th2007

Drive Roaming. DELL PERC4 Controllers

During a recent test run to see if a new PostgreSQL back end server would hasten things up in a main cluster – that has now become CPU bound and NOT IO…… the wizardry of that I will blog about later.

In any case, the short of it is, that we were juggling PERC4 cards around servers (PCI-X here, PCIe there..) and also complete raid 1 and raid 10 arrays too. The cards are supposed to “detect” the correct array type from the drives if the firmware was missing. Anyway, through a comedy of errors, it worked exactly 1/3 times. The other times we had to remember the exact settings of our arrays (stripe, etc) and how it was structured. So we could clear PERC cards and then recreate the arrays – taking special care to not initalise the new arrays.

So in the end, you can move arrays and channels about. And with LVM, even designations like /sda /sdb reording is also not an issue. However you should rely on good old fashioned hand held way of doing things. Before you start write down all the salient details of your arrays first.