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Comment Re: Data integrity (Score 1) 297

SHA256 is not an error correcting code. It can not correct even single-bit flips. If it could, it would be useless as a cryptographic hash. If you could take a hash and some data that was close to the data for which the hash was computed, and find the single-bit flip that would allow the data to match the hash, then you'd have a very easy way of creating SHA256 collisions. And if you had such an algorithm, you wouldn't use it in a filesystem, you'd use it to break all of the systems that rely on SHA256 collisions being difficult to create. If you want error correcting codes in a filesystem, then you'd use an error correcting code, not a cryptographic hash.

Comment Re:Good intentions but potentially harmful (Score 1) 82

I'm sure that venture capitalists would love to fund someone with a new idea and a business model, knowing that they have no recourse when one of the existing players in the market sitting on a large war chest decides to throw ten times the engineering resources at the same problem. First mover advantage only goes so far...

Comment Re: Data integrity (Score 1) 297

My memory is slightly fuzzy, since it's over ten years since I studied this, but here goes:

Single-bit errors in DRAM are caused by the capacitor that stores the data being discharged. This means that the transitions happen in one direction: from charged to discharged. With parity RAM, you can tell that an error has occurred, but you can't tell what the error is. The parity and ECC checks happen in the the digital circuitry and so have no knowledge of the analogue state. Since ECC uses Hamming codes, it can detect more than single-bit errors, but it can only fix one bit flip (the bias isn't actually required, but it does make the code shorter).

Comment Re:Doesn't matter (Score 1) 378

No it isn't. Read the post I replied to:

In the good ol' US of A if you bring your phone to another company, you pay the same thing everyone else is paying. No discount for not getting a new shiney through the new company.

If you bring your phone to another company, you are not going to get a contract with a phone, you're going to get a SIM-only plan.

Comment Re:all i want is BP-rewrite (Score 1) 297

If I have two files, with block IDs ABCDE and EFCGH, how would I place them on disk in such a way that a single sequential read would allow me to read either file? Without dedup, it's easy: ABCDEEFCGH, for example. With partial dedup, you could write them as ABCDEFCGH, eliminating the duplication of the E, but you've still got two copies of C. With full deduplication, if you write the first file contiguously, then you are going to need at least two seeks while reading the second - EF{seek}C{seek}GH.

Comment Re:Oh wow Forbes defends trolls what a surprise (Score 1) 191

The obvious distinction is whether they invest a engineering effort in developing things. Most patent trolls just buy up patents and then try to turn them into money. Companies like ARM also don't make things, but the stuff that they license has obvious value: creating it independently from scratch would require a lot of time and money. Typically, these companies don't just license patents, they also provide detailed designs, engineering support, and so on.

Comment Re:Doesn't matter (Score 2) 378

I only spent a few minutes looking last time I was in the US, but I found lots of mobile phone shops that were willing to give cheaper SIM-only deals and even more such deals were available online. Eventually I decided that since my phone had OSMAnd for offline maps and I had WiFi in the hotel (and a lot of coffee shops and so on), I didn't need to bother with mobile coverage.

Comment Re: Topology (Score 2) 378

When people say GSM, they mean the ETSI standards, including UMTS, HSPA and LTE. Most vaguely recent 'GSM' phones speak at least GSM and UMTS, many also do HSPA and the latest ones do LTE as well. All of the newer standards are also patented, but they're RAND licensed and so there's lots of competition among device makers.

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