On Sun, Mar 1, 2015 at 11:19 PM, Christian Balzer <[email protected]> wrote:
> > > > > > 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 :( > > > > > Using the google shopping (which isn't ideal, but for simplicities sake) > search I see the 100GB DC S3700 from 170USD and the 160GB DC S3500 from > 150USD, which are a pretty good match to the OEM price on the Intel site > of 180 and 160 respectively. > > If I have to buy them personally, that'll work well. If I can get work to get them, then I kinda have to limit myself to whom we have marked as suppliers as it's a pain to get a new company in the mix. > > > 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? > > No, because they start from 200GB and with a 300USD price tag. The 3710s > do not replace the 3700s, they extend the selection upwards (in size > mostly). > I thought I had corrected that - I was thinking the 3700's and typed 3710 :) > > >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... > > > See above, google shopping. The lowballer is Walmart, of all places: > > http://www.walmart.com/ip/26972768?wmlspartner=wlpa&selectedSellerId=0 > > > > > > > > > > > > > > > > > > > > > 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. > > > > If you have existing servers that run linux and have been up for > reasonably long time (months), iostat will give you a very good idea. > No ideas about Windows, but I bet those stats exist someplace, too. > I can't say months, but at least a month, maybe two - trying to remember when our last extended power outage was - I can find out later. > > For example a Ceph storage node, up 74 days with OS and journals on the > first 4 drives and OSD HDDs on the other 8: > > Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn > sda 9.82 29.88 187.87 191341125 1203171718 > sdb 9.79 29.57 194.22 189367432 1243850846 > sdc 9.77 29.83 188.89 191061000 1209676622 > sdd 8.77 29.57 175.40 189399240 1123294410 > sde 5.24 354.19 55.68 2268306443 356604748 > sdi 5.02 335.61 63.60 2149338787 407307544 > sdj 4.96 350.33 52.43 2243590803 335751320 > sdl 5.04 374.62 48.49 2399170183 310559488 > sdf 4.85 354.52 50.43 2270401571 322947192 > sdh 4.77 332.38 50.60 2128622471 324065888 > sdg 6.26 403.97 65.42 2587109283 418931316 > sdk 5.86 385.36 55.61 2467921295 356120140 > I do have some linux vms that have been up for a while, can't say how many months since the last extended power outage off hand (granted I know once I look at the uptime), but hopefully it will at least give me an idea. > > > > > > > > > > > > > > > So it's 2x1Gb/s then? > > > > > > > client side 2x1, cluster side, 3x1. > > > So 500MB/s with trailing wind on a sunny day. > > Meaning that something that can do about 400MB/s will do nicely, as you're > only even going to get near that when doing massive backfilling AND client > writes. > Yeah. Eventually one day I'll get them to get 10Gig, but it won't be until it comes way down in price. > > > > > > > > > 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. > > > Yup, 2 is clearly better, I'd go with 2 100GB DC S3700s. > > I'll have to see what I can get done this week. Thanks for the input - it's really clarified the SSD usage a lot! -Tony
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