On Sun, Mar 1, 2015 at 10:18 PM, Christian Balzer <chibi@xxxxxxx> wrote:
On Sun, 1 Mar 2015 21:26:16 -0600 Tony Harris wrote:
> On Sun, Mar 1, 2015 at 6:32 PM, Christian Balzer <chibi@xxxxxxx> 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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