I have a server with 2 SSDs:  Model Family:     Intel 520 Series SSDs Device Model:     INTEL SSDSC2BW240A3F Firmware Version: 400i User Capacity:    240,057,409,536 bytes [240 GB] Sector Size:      512 bytes logical/physical   On them I have 3 mdraid mirror devices (md0,1,2) formatted with EXT4 filesystem. I'm using mbr (not gpt) partition table. All 3 filesystems are mounted with discard mount option.   /dev/md0 on / type ext4 (rw,discard,errors=remount-ro) /dev/md2 on /vservers type ext4 (rw,discard) /dev/md1 on /var type ext4 (rw,discard)   The PROBLEM is that whenever I reboot the server, fstrim -v /any_mountpoint says it needed to trim ALL of the unused space. Once I do the full fstrim of the filesystems, everything works as expected until the next reboot. Running fstrim after a reboot again trims the whole filesystem.  Could somebody explain to me what I'm doing wrong? I thought ext4 remembered the already trimmed parts of filesystem (on my desktop with 1 ssd, it does). This is on Ubuntu 14.04 with 3.13.0-23-generic kernel.
When I installed my SSD I just mounted with discard and didn't sweat it. However today I was reading about the pros and cons of using fstrim instead and decided to run the program to get an idea of how long it would actually take (still with my partitions mounted with discard). The command took several minutes on both my root and home partitions. For my home partition I used -v and got this:  $ sudo fstrim -v /home /home: 137494052864 bytes were trimmed   This is more than the amount of free space on the partition!  $ df -h /home Filesystem      Size  Used Avail Use% Mounted on /dev/sda2       206G   78G  118G  40% /home   Subsequent runs finish in less than a second, eg:  $ sudo fstrim -v /home /home: 0 bytes were trimmed   Surely if I have always had the partition mounted with discard, fstrim should not trim a large amount of data like that? The discard option is definitely enabled, here are the relevant fstab lines:  UUID=xxxxxxxx...    /          ext4   noatime,discard,errors=remount-ro  0      1 UUID=xxxxxxxx...    /home      ext4   noatime,discard,errors=remount-ro  0      2   And mount output lines:  /dev/disk/by-uuid/xxxxxxxx... on / type ext4 (rw,noatime,discard,errors=remount-ro,stripe=128,data=ordered) /dev/sda2 on /home type ext4 (rw,noatime,discard,errors=remount-ro,stripe=128,data=ordered)   The SSD is a TOSHIBA THNSNS256GMCP. Why does this happen?
Where did the disco repos go, or what is going on? How can I get rid of this black hole in my minecraft world? I have interesting bug that I have experienced before but has gone away on its own. This one is not going away though.  I have a giant stripe or chunks missing from my desert biome, I would say probably 7 chunks long.  I'm guessing the chunks are corrupted or something, what was hoping to figure is whether it can repaired or reverted.  Here is a picture of the problem. What packages do you use and recommend for creating graphics in your LaTeX documents?     As this is a community wiki post, please add your package to the accepted answer (or add a comment, and someone with >100 rep will add it to the CW answer), and include a brief description of what differentiates it from others and how it can be used (GUI drawing tool which generates code, type in raw text, or generates image for inclusion in document).   We'll eventually sort these answers under headings. Is there any way of making a Minecraft server lower than the current version? So me and my friends manged to make a server in Minecraft for us to play on and we would like to add mods. But the mods we want to add are a few versions lower than the updated version. Is there any way of making a server with a lower version of Minecraft that people can still play on? The result of ls * , ls ** and ls *** I know using the command ls will list all the directories. But what does the ls * command do ? I used it and it just lists the directories. Does the star in front of ls mean how deep it will list the directories? Rooks on a 8 by 8 checker board. Probability problem Two rooks are placed on an 8 by 8 chessboard such that they're in different squares. What is the probability they can't attack each other? Rooks can attack each other if and only if they're in the same row or column. I know that there are questions like this but they give the general numbers not the probability I am not sure how to start the questions and I have looked at this questions for hours. Any help would be welcome. Is stopwatch benchmarking acceptable? Does anyone ever use stopwatch benchmarking, or should a performance tool always be used?  Are there any good free tools available for Java?  What tools do you use?  To clarify my concerns, stopwatch benchmarking is subject to error due to operating system scheduling.  On a given run of your program the OS might schedule another process (or several) in the middle of the function you're timing.  In Java, things are even a little bit worse if you're trying to time a threaded application, as the JVM scheduler throws even a little bit more randomness into the mix.  How do you address operating system scheduling when benchmarking? I have an UTF-8, polish text in .tex file. When I open it with my LEd (LaTeX editor), it shows ok (all characters can be seen). But when I try to compile it, I get error:  Package inputenc Error: Keyboard character used is undefined (inputenc) in inputencoding `utf8'.   I have to copy the text, cut it and paste to Notepad++, change (not convert!) encoding from UTF8 to ANSI (the polish characters will be missed and replaces with some random characters). Than copy it again and paste to LEd (in that editor, characters display bad also). But now I can compile my pdf and in it, the encoding is right again.  Is there a way to set encoding in the way I will see characters in LEd propertly and I will be able to compile it and I will get good characters in pdf?  The begging of my code:  \documentclass[12pt]{report} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage{graphicx} \usepackage{amsmath,amssymb,amsfonts} \usepackage{txfonts} I'm trying to load a field value (machine name: field_theme_image) from a content of node value 3, in "page--front.tpl.php".  &lt;?php   $node=node_load(3);   print $node-&gt;field_theme_image[$node-&gt;language][0]['uri']; ?&gt;   Using the above code I'm not getting full URL value. Please see the image below. I can see the path value in Devel themer. This has happened to me many times in the last 5 years: an upgrade broke my system. Each time I end up with this situation, I have to reinstall the whole system, which is really annoying.  Is there any way to roll back the most recent upgrade to be able to have a functional system without reinstalling? If not, which is the best way to suggest this as a top priority idea?   I read this idea was described in brainstorm.ubuntu.com, but it feels it is dead... and the forums are full of examples of upgrades breaking things, that's why I feel something needs to be done about this topic. Thanks! My book uses the argument that the multiplicities of a few macrostates in a macroscopic object take up an extraordinarily large share of all possible microstates, such that even over the entire lifetime of the universe, if each microstate had an equal chance of being accessed, fluctuations away from equilibrium would never occur.  My question to this statistical proof is this: In the real world, is there really an infinitesimal but nonzero chance that macroscopic systems could access some of the more unlikely macrostates (e.g. heat transfer from a cold object to a hot object)? How do I calculate the challenge rating of monsters that feature abilities that do not directly do damage?  For example, my homebrew monster has the two following abilities:     The target takes a Constitution saving throw. On a failure, it drops to 0   hit points.   This one could be used on a character with 10 hit points, or 100, which creates drastically different damage results depending on character level.     All creatures within 60ft take a Wisdom saving throw. Each target that fails is stunned for 1 round.   This can be extremely dangerous if this monster is paired with monsters that can make use of the stun condition, but it is virtually useless if the monster is alone.  I'm sure there are infinitely more examples of this type of thing.  How do we calculate CR for monsters that do not rely on standard attacks? I'd never heard of anycast until a few seconds ago when I read "".  The wikipedia "" article on it is quite formal and doesn't really evoke a mental picture of how it would be used.  Can someone explain in a few informal sentences what "anycast" is, how you configure it (just in a general sense), and what its benefits are (what does it make easier)? Rotating image / marker image on Google map V3 Previous questions confirmed that Hex can last through multiple encounters (assuming my warlock's concentration doesn't get broken by a club to the head or the like) and at higher levels even through a short rest.   My question is how targeting Hex works when trying to keep it up for extended periods of time.   Can I just cast it on nothing and keep it up until a valid target presents itself or is an initial valid target required?   Then later, does changing the target of the Hex require that the original target is brought to 0 HP?   Once the initial target dies does the spell stay active even if I don't immediately choose a new target?  My suspicion from reading the spell is that it needs an initial target, but then from that point on I can just keep it up after that target dies until it either expires or a new target presents itself. Is this correct? There's already a question like this  so that my question could be considered duplicate, but I'll try to make my point clear that this is a different question.   Is there a way to derive  from the Lorentz' Force law or just from Maxwell's Equations?   The point is that we usually define, based on experiments, that the force felt by a moving charge on the presence of a magnetic field is $\mathbf {F} = q\mathbf{v}\times \mathbf{B}$, but in that case the magnetic field is usually left to be defined later.   Now can that force law be used in some way to obtain Biot-Savart law like we obtain the equation for the electric field directly from Coulomb's Force law?  I wanted to know that because as pointed out in the question I've mentioned, although Maxwell's Equations can be considered more fundamental, those equations are obtained after we know Coulomb's and Biot-Savart's laws, so if we start with Maxwell's Equations to obtain Biot-Savart's having use it to find Maxwell's Equations then I think we'll fall into a circular argument.   In that case, without recoursing to Maxwell's Equations the only way to obtain Biot-Savart's law is through observations or can it be derived somehow? $\Bbb Q$-linear is equivalent to additive Maximum weight an average bicycle can carry? I never really bothered to keep my Hotmail contact information up to date, so now that I connected it to Windows 8, suddenly I see all this outdated contact information or people I've long stopped talking to.    I don't see any buttons or options where I can click to delete someone.  So how do I clean up my Windows 8 People app and remove these contacts? I have noticed that the smackpacks say on the package that the package is meant for a 5 gal. batch and that you should pour the pack directly into the wort.   On the otherhand - nearly everyone tells me to always make a starter.   Is this just because making a starter never hurts or does the package contain wrong instructions?   I would have guessed that the yeast producers would tell you on the package if you should need some extra steps to get a good product.