justin
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| reply to fcisler
Re: Benchmarking? I think not.
Yeah I know there are instances of upgrades killing features that optimize for speed. Happens all the more often when there are layers involved for instance for a while LVM killed performance that you got out of the underlying devices. I tend not to automatically upgrade critical production stuff that works unless I need a new feature, for that very reason.
Not concerned here because the dots are all joined up. The spec published by IBM (but not Dell) matches the throughput test I've done, which matches the benchmarks done on the all.thingsit blog, give or take 20%. lower level benchmarks match higher level ones. Stuff like that.
As for RAID5 I've not tested it yet but that is very clearly what the IBM manual says vs RAID10. Something about the firmware in the controllers optimized for RAID5 LUNs  It may not really be worth it because if the whole shabang is capped at around 400mb/sec or so then there isn't a lot of point increasing sequential read throughput from 200mb/sec to perhaps 300mb/sec with the potential to slightly decrease write speed unless you really need the extra space RAID5 provides. There is also the issue that if all the drives are the same age they may start failing in batches and in that case you probably want RAID10 not RAID5 as it can suffer more drive failures!
The MD3000 stores the firmware on the pluggable controllers (I think). Anyway, it stores nothing on the drives thats for sure. The firmware isn't very large, or complex. It does support some basic performance collection so you can check if you have drive hot spots but the management interface does not give you any tools to review this info - you're on your own sucking that data out and plotting it or whatever. There are also those two "unlockable" features at ridiculous cost to look at (LUN copy and LUN snapshot). I'm not bothering with them because LVM2 gives the same thing for free. |
