Jake, Most of thenumbers you are showing are just the clocked speeds on busses and cables. Certainly the components can clock at those speeds, but the biggest issue with lower-end components is whether they can actually feed and sustain data at that rate, and how well they handle contention for resources. Generally this comes down to size of buffers, and whether have fast or wide enough processors at those interface points.
But it sounds like for the business Backblaze is in they are building something that is big rather than fast (or at least something that is fast enough). And certainly if you can parallelize the system enough (and maintain reliablity) then you probably even achieve cheap and fast. Regards, Martin martinvisse...@gmail.com On Thu, Sep 3, 2009 at 12:40 PM, Jake Anderson <ya...@vapourforge.com>wrote: > On 03/09/09 10:37, Mark Walkom wrote: > >> I was thinking the same, but I reckon because they are just backing >> up/archiving data it wouldn't be too bad. >> ie They aren't looking for huge performance, just huge, cheap storage. >> >> >> 2009/9/3 Morgan Storey<m...@morganstorey.com> >> >> >> >>> I know I am a geek but that is hot. >>> I am wondering if they see any throughput issues with the sata backplanes >>> and pci sata cards. >>> >>> >> The backplanes are probably fine, each sata cable is good for > ~300mbytes/sec most physical disks couldn't hope to hit that. > lesse what their maximum xfer rate is. > each drive can hit 103mb/sec average (better than I thought) > each sata channel will max out at 250mbyte/sec > > so they are going to be loosing some bandwidth there. > their backplanes take 5 disks, so a potential bandwidth of well call it > 500mbyte/second > so 50% is out the window there actual bandwidth per 5 disks is going to be > 250mbyte > > they have 9 of these channels for a total bandwith available of > 2250mbyte/sec (2 gigabytes a second, that'll rip some dvds fast) > > standard PCI tops out at 133mbyte/sec so thats out ;-> > > it looks like they are using PCI-E SATA cards > the mbo they have and the cards they are using indicate they have 3x of > something like this > http://www.syba.com/index.php?controller=Product&action=Info&Id=861 > which maxes out at 250mbyte/sec per (1x PCI-E 1x lane) > and one 4 port card which if it comes from that mob must be a PCI by the > look of things. > but I'll assume that its PCI-E and at least 4 lanes. > > so the total xfer rate is 1750mbyte/sec > (or 883 if they are using the PCI card) > > Vs the total possible xfer rate of 4500 > they aren't doing *too* badly > > given that on a gigabit ethernet connection you are lucky to push > 30mbyte/sec (or 60 if you tweak it), I think its not going to be a big issue > ;-> > > > If they wanted more oomph their best bet would be to put 2x 16 port PCI-E > 16x cards into a motherboard that supported it (most decent SLI motherboards > will do that) > > better still one with 4x pci-E 16 slots so that you can put some 10gigE > cards in as well something like > > http://www.aria.co.uk/Products/Components/Motherboards/Socket+AM3+(AMD)/MSI+790FX-GD70+AM3+Motherboard+with+4+x+PCIe+x+16+?productId=36604<http://www.aria.co.uk/Products/Components/Motherboards/Socket+AM3+%28AMD%29/MSI+790FX-GD70+AM3+Motherboard+with+4+x+PCIe+x+16+?productId=36604> > say (but with intel of course ;->) > > That should net you (assuming you use dual port 10gig-E nics) an xfer rate > out of the box of around 2400mbytes/sec > almost fast enough to spy on teh entirez intarwebz!! > > -- > SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ > Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html > -- SLUG - Sydney Linux User's Group Mailing List - http://slug.org.au/ Subscription info and FAQs: http://slug.org.au/faq/mailinglists.html
