Can anyone please tell me, from experience, if it's possible to upgrade the hard drives in a RAID 10 system from 250GB HDD's to 500GB / 750GB HDD's, while the server is running? The server runs CentOS 5.5 x64.
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So, I'm wondering, is it possible (and safe) to upgrade the existing drives to larger drives in a running server?
Assuming we're discussing hardware RAID then the answer is *maybe*. Some raid cards support array expansion through disk replacement and some don't. Your vendor may be correct in saying the systems doesn't, they may not. Only way to know for sure is to reviews the spec sheet of the raid controller you use and look for something along the lines of "Online Capacity Expansion" (IBM's term for the capability) or the like.
I went through this exercise recently with some older IBM server's I inherited in my department. We wanted to upgrade the disk's in one server from 36's to 74's and after consulting with my vendor, and my own digging, it was determined to be impossible. The new controllers being shipped otoh do come with the capability and I've made a point of only ordering cards with the feature.