23 January 2007

Half Terabyte server update

I downloaded best performance meter available -- Iometer. As the Iometer User's Guide says, Iometer is an I/O subsystem measurement and characterization tool for single and clustered systems. It was originally developed by the Intel Corporation and announced at the Intel Developers Forum (IDF) on February 17, 1998 - since then it got wide spread within the industry. Look more: www.iometer.org

So, I played in my home network, particularly with my HTMS (Half Terabyte Media Server) RAID subsystem.

My HTBMS server config:

So, test data:
Maximum read throughput: 100 MB/s (with >1Mb packets)
Maximum write throughput: 10 MB/s
Maximum I/O ops/s: 10 000 ops/s (with 512 Kb packets)
I am not happy with write performance. Read performance is very good, also through gigabit NIC and my home lab, all gigabit. Problem for low write performance is parity calculation during write in RAID5 model. Option is to go for RAID 0 or 1, but I'd like to stay in RAID5, because of reliability and space. Buying model 1640 I didn't have any idea, that parity is calculated by computers CPU. So, processor load is 100% during large writes. I found that RocketRaid 1810a has hardware XOR parity module, so CPU is not overloaded. Have to swap RAID controller, or I'm not satified.
I found extremely interesting forum thread about buidling cheap and powerful RAID5. Must reading for everybody, who are trying it at home.

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