On Sun, Mar 1, 2015 at 10:18 PM, Christian Balzer <ch...@gol.com> wrote:
> On Sun, 1 Mar 2015 21:26:16 -0600 Tony Harris wrote: > > > On Sun, Mar 1, 2015 at 6:32 PM, Christian Balzer <ch...@gol.com> wrote: > > > > > > > > Again, penultimately you will need to sit down, compile and compare the > > > numbers. > > > > > > Start with this: > > > http://ark.intel.com/products/family/83425/Data-Center-SSDs > > > > > > Pay close attention to the 3610 SSDs, while slightly more expensive > > > they offer 10 times the endurance. > > > > > > > Unfortunately, $300 vs $100 isn't really slightly more expensive ;) > > Although I did notice that the 3710's can be gotten for ~210. > > > > > I'm not sure where you get those prices from or what you're comparing with > what but if you look at the OEM prices in the URL up there (which compare > quite closely to what you can find when looking at shopping prices) a > comparison with closely matched capabilities goes like this: > > http://ark.intel.com/compare/71913,86640,75680,75679 > > I'll be honest, the pricing on Intel's website is far from reality. I haven't been able to find any OEMs, and retail pricing on the 200GB 3610 is ~231 (the $300 must have been a different model in the line). Although $231 does add up real quick if I need to get 6 of them :( > You really wouldn't want less than 200MB/s, even in your setup which I > take to be 2Gb/s from what you wrote below. > Note that the 100GB 3700 is going to perform way better and last immensely > longer than the 160GB 3500 while being moderately more expensive, while > the the 200GB 3610 is faster (IOPS), lasting 10 times long AND cheaper than > the 240GB 3500. > > It is pretty much those numbers that made me use 4 100GB 3700s instead of > 3500s (240GB), much more bang for the buck and it still did fit my budget > and could deal with 80% of the network bandwidth. > So the 3710's would be an ok solution? I have seen the 3700s for right about $200, which although doesn't seem a lot cheaper, when getting 6, that does shave about $200 after shipping costs as well... > > > > > > > > > Guestimate the amount of data written to your cluster per day, break > > > that down to the load a journal SSD will see and then multiply by at > > > least 5 to be on the safe side. Then see which SSD will fit your > > > expected usage pattern. > > > > > > > Luckily I don't think there will be a ton of data per day written. The > > majority of servers whose VHDs will be stored in our cluster don't have a > > lot of frequent activity - aside from a few windows servers that have DBs > > servers in them (and even they don't write a ton of data per day really). > > > > Being able to put even a coarse number on this will tell you if you can > skim on the endurance and have your cluster last like 5 years or if > getting a higher endurance SSD is going to be cheaper. > Any suggestions on how I can get a really accurate number on this? I mean, I could probably get some good numbers from the database servers in terms of their writes in a given day, but when it comes to other processes running in the background I'm not sure how much these might really affect this number. > > > > > So it's 2x1Gb/s then? > client side 2x1, cluster side, 3x1. > > At that speed a single SSD from the list above would do, if you're > a) aware of the risk that this SSD failing will kill all OSDs on that node > and > b) don't expect your cluster to be upgraded > I'd really prefer 2 per node from our discussions so far - it's all a matter of cost, but I also don't want to jump to a poor decision just because it can't be afforded immediately. I'd rather gradually upgrade nodes as can be afforded then jump into cheap now only to have to pay a bigger price later. > > > Well, I'd like to steer away from the consumer models if possible since > > they (AFAIK) don't contain caps to finish writes should a power loss > > occur, unless there is one that does? > > > Not that I'm aware of. > > Also note that while Andrei is happy with his 520s (especially compared to > the Samsungs) I have various 5x0 Intel SSDs in use as well and while they > are quite nice the 3700s are so much faster (consistently) in comparison > that one can't believe it ain't butter. ^o^ > I'll have to see if I can get funding, I've already donated enough to get the (albeit used) servers and nic cards, I just can't personally afford to donate another 1K-1200, but hopefully I'll soon have it nailed down what exact model I would like to have and maybe I can get them to pay for at least 1/2 of them... God working for a school can be taxing at times. -Tony > > Christian > >
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