the first command reads the entore disk (make sure you specify the right value, sda for the first disk, sdb for the second) and ignores the results. The second command is usueful for recovering data from a failing drive and will not abort when it runs into an error
basically, you have a bunch of 'maybe-error' sectors, that might be revealed to be fine or might be triggered into full 'definitely-error's (which could potentially lose data - often, a failing drive can only be read once if at all and it's stupid to waste that single read on error detection when you could have recovered data with it)
this will happen on the next read (hence surface scan)
@Overflowh I generally recommend crashplan these days. You can use their software for free if you have your own place to store the data, or they provide a very reasonable online server to store stuff offsite
I think I'm paying $4/month for 15-minute incremental backups of my linux media server, windows desktop, mac laptop, my mother's desktop and laptop, sister's laptop, dad's laptop, and other sister's laptop. About 10TB worth of data currently.
As the tech guy that gets the call when stuff doesn't work in my family, it's so very satisfying to know that even my sisters can't screw something up where they lose data.
@Overflowh Yeah, the upload can bite you, but with my parents I just capped it at a % of their total upload and then just let it run for... 4 months is it now?
took forever, but it eventually got all their photos and movies backed up
@DarthAndroid Well, I think it's impossible. My upload is, officially, 386kbps, but really it rarely pass the 35kbps.. At that speed, it makes my connection useless.. and taking just a % of it, it would require years to upload everything..
E.g. dells website told me it needed to contain a number. They mean "We only check the first 8 chars of your password for numbers. Yours are past char 9"
@Bob @Overflowh Well, Crash plan's software can still be of use. It also supports backing up to local LAN boxes, and removable harddrives. My desktop actually backs up to both CrashPlan's off-site servers and my local media server
@DarthAndroid This is the think that captured my attention earlier.. I will surely give a try to this crashplan software.. Actually, I back up things on my external hard drive, but I'm quite messy
@Overflowh It's open source, and I haven't personally checked, but it's popular enough that I feel comfortable that enough people that have the free time have looked over it.
I still just stick with my PwdHash stuff though :)
Anyway, I think I will use my brain until it will collaborate :P when it will start giving me problems like the hard disk of my laptop, I will use keepass :P
@DarthAndroid No well, not the best speed. If I lived at 34 kilometers from here, I could access the optical fiber, and they say that can be 100 MB in download and 10 in upload.
@Bob @JourneymanGeek @DarthAndroid this looks cool osv.io
> OSv runs off-the-shelve JVM today. We plan to change the JVM by exposing OS internals and direct access for page tables, scheduling decisions and the raw IO layer
sounds like it's 100% secure... I mean, JVMs never have vulnerabilities that allow users to inject code, right? imagine the havoc they could wreak with kernel access directly :D
fact: Oracle's Java HotSpot JVM has an extremely performant, stable, scalable multithreaded garbage collector and an extremely optimized JIT for bytecode, both of which are years more mature than the JIT in web browsers' JavaScript engines
now... take Java Script and run it through that JIT and clean up behind it using Java's GC
There aren't solid benchmarks yet, but the few preliminary reports are very, very exciting in terms of what the JVM is capable of with compiled javascript.
There's a reason that JPython was several orders of magnitude faster than the C implementation of python for a while.
in about 2010 one of my professors told me we have 30 years of theoretical computer science research left to do before we've discovered most of the significant, relevant and useful optimizations that can be done in an efficient manner for JIT runtimes of this sort
there's a lot of upside left
and that's taking into account what Java, LLVM, etc. can do today
there are also some theoretically known, discovered techniques that can be done in JIT optimization passes, but which are not normally done today because, on modern CPUs with typical code sizes, it would delay program startup by too long, so we either have to wait until CPUs get faster, or figure out how to work in those optimizations while the app is running without disturbing it
or someone needs to come out with a sort of "compile-time JIT" that will run the program with typical workloads, profile it, determine all possible optimizations (even the very very slow to produce / expensive ones), optimize it all to hell, then save the machine code binaries out to disk
static compilers don't actually run your code so they're very limited in what they can do
@allquixotic That's part of the goal of the -server flag. Doesn't save anything for later, but "I want you to not worry about startup time and do in-depth analysis of this code before running it."
Profile-guided optimization (PGO, sometimes pronounced as “pogo”) is a compiler optimization technique in computer programming to improve program runtime performance. In contrast to traditional optimization techniques that solely use the source code, PGO uses the results of test runs of the instrumented program to optimize the final generated code. The compiler is used to access data from a sample run of the program across a representative input set. The data indicates which areas of the program are executed more frequently, and which areas are executed less frequently. All optimizations be...
Intel's freeware, proprietary x86/x86_64 compiler does PGO for C/C++
that's the closest that non-VM languages come to the types of optimizations that JIT does
@DarthAndroid Puts far too much trust in the user. "Hey, the first time you run this, pretend you're running everything in the average case so we can optimise it."