I just picked up an HP DL180 G6 like this ( http://r.ebay.com/lHyBzS) but have the 3.06GZ 12MB L3 cache and 96GB RAM. I am trying to figure out the best way to configure my RAID for reliability of the OS, but also to maximize the performance of VOD. I have around 1TB of storage needs and growing and 25X 146GB 15K SAS drives which gives me 3650GB to play with.
Based off what I am reading on Wikipedia (http://en.wikipedia.org/wiki/Standard_RAID_levels) I had considered sectioning it out like this:
HP Smart Array P410 Controller
5 drives in RAID 5 - OS Drive (438GB)
10 drives in RAID 0 - Content disk 1
10 drives in RAID 0 - Content disk 2
I wasn't sure because of the 2nd network port if I should break those last 20 up into separate RAIDs, or maybe you will tell me I should really have 5 separate RAID 0 going on for max performance and divide up my content into multiple applications to point to multiple content folders or I could just put them all on a single RAID 0 if that works out.
I will be connecting to the internet with dual 1GB connections and hope to serve up around 2000-2500 users doing VOD with no transcoding as we already have all qualities encoded already. I also have 6 300GB 10K SAS and 2 450GB 10K I could use, but wasn't sure if there was too big of a performance hit on the 10K drives, but the extra space would be nice for future content.
===== Side track ====
I was running the load testing tool yesterday on an HPDL360 G5 / 32GB RAM 4X72GB 15K SAS in RAID 0 and was able to get about 1100 simultaneous connection with 175 sample files of varying bitrates before the network was saturated so I am hoping to use 2 1GB ports and am currently not sure if that means 2 applications, or if I can just tell it to listen to both IPs in the vhost.xml. Was planning on figuring that out next
One thing I did notice is that when I ran the load testing tool on the last server, the RAM usage kept getting higher and higher each time I ran the tool, but never dropped back down. It didn't seem to impact the performance of the server, but that was just within 1-2 hours of running different tests, not sure what the implications would be for it running 24X7X365. I tried identifying the application using all the RAM using "top" and "ps -aux" but couldn't get it to drop back down below 25GB in use even after restarting all processes like apache, wowza, mysql, memcached. I still need to do all the performance tuning on the real server, this last one was just a test to see what happened with the CPU and Memory with that many users. (if you are wondering, CPU got up to around 75% usage only after 800 users, memory got progressively more filled to 98%). I never could figure out how to determine the load on the hard drives, iotop, and iostat didn't seem to see it at all.