On Jan 25, 2012, at 4:50 PM, John R Pierce wrote:
> On 01/25/12 4:27 PM, Jason T. Slack-Moehrle wrote:
>> can you explain to the calculation to determine that 300gb is 2mbps?
>
> 300GB (big B for byte) / 30 days / 24 hours/day / 3600 seconds/hour,
> and
> I get 0.12MB/second, so multiplying by 10 to get bits allowing for
> basic
> protocol overhead, I come up with 1.2Mbit/sec sustained average.
>
>
> racking 2 PiB (or 2048TiB) of nearline grade storage will require
> about
> 1000 3.5" 3TB drives, allowing for a reasonable raid level and
> suitable
> number of hotspares. If its frequently updated transactional
> database
> storage, I'd want to use raid10. Using somethign like the Supermicro
> 847 chassis, you can get 36 drives plus a server in 4U, and draw about
> 700 watts actual in use.... I estimate you'll want about 28 of these
> servers, which will take two full racks and draw about 20KW, or 180
> amps
> off 120V household circuits (realistically, you'll need 208V for this
> many servers). You'll also need about 10-15KW worth of air
> conditioning equipment to deal with the generated 68000 BTUs of heat.
> HVAC will push your power usage up to the 30-40kW range, or 2500
> KWH/month, at $0.20/KWH typical residential power usage, you're
> looking
> at a $5000/month power bill, give or take.
>
> those 28 SuperMicro servers will cost about $200,000 for the 1000 3TB
> enterprise nearline disks, plus another $200,000 or so for reasonably
> well configured servers. 20KVA of redundant UPS and 70000 BTU worth
> of
> computer room A/C will add a good chunk more $$$$ to this.
>
> are you serious?
Nice analysis.
Yea the heat footprint alone will require some good AC. I'm open
minded and am intrigued on who this will be pulled off but still,
sounds crazy and not too well thought out.
I do like the not for profit spin which helps the cause out.
A quick search found this;
http://bioteam.net/2011/08/why-you-should-never-build-a-backblaze-pod/
Basically its a sort of why not to use a backBlaze but we sort did ...
- aurf
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