Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 internet speed test! ×

Comment Re:I've noticed that, but something else interesti (Score 1) 154

I found GPS directions were a good way of getting to know my way around when I moved here, but I looked at the planned route before I set off (walking or cycling) and was then able to look more at my surroundings. The phone in my pocket would tell me which turning to take, and so I'd get to know the routes very quickly and not need to look at the map. After a week, I wasn't bothering to set the directions. Having the GPS also gave me more confidence to explore - I could wander around in a random direction and know that I'd never actually get lost. Just like any other tool, the benefits of a satnav depend entirely on how you use it.

Comment Re:Maps technology is lost... (Score 2) 154

We bought a new house last year and it was a few months before it was on most maps[1]. The number of delivery drivers that got lost was incredible. We gave them clear directions from the nearest main road, but most of them couldn't manage to follow them. Our road is just past a large office block and so all they needed to do was get to that office building (been there for decades, on all of the maps) and then follow the road around. We also told them which turning to take off the road that led to that one. It appears that most of them could not read street signs and didn't know whether they were heading towards or away from the city centre.

[1] OpenStreetMap had it before we looked at it, Google still doesn't. I still find the comment that OSM is a parody from the Google Maps lead amusing - apparently looking pretty is far more important than having accurate data.

Comment Re:What I thought (Score 2) 244

A lithium-ion battery is basically a bomb with a small circuit saying 'don't explode, don't explode, don't explode'. They're banned from aircraft holds because the don't-explode circuits turn out not to be as reliable as previously thought. It amazes me that I'm allowed to carry a few of them onto a plane, but not a small bottle of water (though I can buy one at an overprices shop, or I can buy something a lot more flammable in Duty Free).

Comment Re:they forgot the most important one. (Score 2) 71

Google doesn't 'sell' your personal information, because they consider it an asset. They do, however, sell the right to put adverts in front of people matching certain criteria. This has been shown to allow third parties to infer information that Google has about you. The first attack demonstrating this placed adverts for a pizza place with a free pizza code and asked for it to target people in a specific region who identified as gay. Users then went to the pizza company web site, entered their name, address, and coupon, and suddenly someone else had a database of people that Google knew were in a certain area and gay - a very useful took for hate groups. That was years ago and there are now far more subtle attacks that give better information.

Comment Re:SSD as cache (Score 1) 61

You can get 384GB(6x64) of ECC server ram for $5,202 on newegg...

So you can get 384GB of RAM for a bit more than 8TB of NVMe flash (not sure what the XPoint pricing is going to be).

For a 2K to 5K difference...the ram memory beats all...and it is not THAT much more expensive.

It's about 20 times as expensive per GB. You're arguing that the better latency and throughput of the RAM is going to outweigh the increased capacity of the NVRAM. That's by no means clear. If your working set fits entirely into that 384GB RAM cache, then the RAM will definitely be faster, but your working set is 1-4TBs (not that uncommon for a SAN device) then the RAM solution is going to be a lot slower than one with 128GB of RAM and 4TB of NVMe flash. For a smaller array, that $5K price difference is enough to replace all of the spinning rust disks with NVRAM, which will give you even better performance.

If you want under 2K...what about a 2xM.2 pcie card(~$100-$150) with two 1TB Samsung PRO 950 M.2 cards for ~$1400? Run that in raid0 and you would probably be equal or better then the current Xpoint offering spec wise.

Except that the one place that XPoint does seem to do a lot better than flash is in random reads, which is the main performance bottleneck for a cache device.

Comment Re:Cache? (Score 1) 61

The endurance listed is 30 drive writes per day for the 375GB model. That's 11.25TB/day, or about 130MB/s sustained 24/7 writes. A cache device should be spending 90% of its time being read, rather than written (or it's not doing that good a job as a cache[1]), which means that even if you're reading from it at about half of its peak rate every second of every day and getting then it's going to last its rated lifetime. Additionally, for a cache device, we really don't care if it burns out. When it does, we don't lose any data, we just take a performance hit until it can be replaced (we've had flash L2 ARC devices die quite a few times), but we really do care a lot about random read performance from the cache drive while it's working.

[1] I just checked the ARC stats on one of our machines. We're getting over 98% hit rates from the ARC and only about 55% from the L2 ARC, so we'd probably wear out one of these a bit faster. That said, this machine has 256GB of RAM and is only using 320GB of L2 ARC, so it's not too surprising that the L2 ARC is not doing a great job: once the working set goes past about 150-200GB (ARC size), it's going to grow past 500GB (ARC + L2 ARC size) pretty quickly.

Slashdot Top Deals

How can you do 'New Math' problems with an 'Old Math' mind? -- Charles Schulz