There are several layers at which a disk error can be simulated. If you are testing a single user-space program, probably the simplest approach is to interpose the appropriate calls (e.g. write()) and have them sometimes return an error. The libfiu fault-injection library can do this using its fiu-run tool. Another approach is to use … Read more
Say you have a file with many empty bytes \x00. These many empty bytes \x00 are called holes. Storing empty bytes is just not efficient, we know there are many of them in the file, so why store them on the storage device? We could instead store metadata describing those zeros. When a process reads … Read more
https://web.archive.org/web/20161221112438/http://www.toadworld.com/platforms/oracle/w/wiki/11001.oracle-b-tree-index-from-the-concept-to-internals Notes: Databases do not directly implement indexes based on B-tree but on a variant called B+ tree. Which according to wikipedia: A B+ tree can be viewed as a B-tree in which each node contains only keys (not key-value pairs), and to which an additional level is added at the bottom with linked leaves. … Read more
Finally a reliable solution! Two of them, actually! Check /sys/block/sdX/queue/rotational, where sdX is the drive name. If it’s 0, you’re dealing with an SSD, and 1 means plain old HDD. I can’t put my finger on the Linux version where it was introduced, but it’s present in Ubuntu’s Linux 3.2 and in vanilla Linux 3.6 … Read more
(Comment for others landing here as @Marta explains that the problem no longer persists on their machine.) In general, any performance issue in Visual Studio should be reported to Microsoft. It’s easy to do this directly from VS using the Report a Problem tool. That feature will automatically attach logs/traces which are shared privately with … Read more
Example: Getting human readable size like 1 Gb String memory = bytesToHuman(totalMemory()) /************************************************************************************************* Returns size in bytes. If you need calculate external memory, change this: StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath()); to this: StatFs statFs = new StatFs(Environment.getExternalStorageDirectory().getAbsolutePath()); **************************************************************************************************/ public long totalMemory() { StatFs statFs = new StatFs(Environment.getRootDirectory().getAbsolutePath()); long total = (statFs.getBlockCount() * statFs.getBlockSize()); return total; … Read more
For most information, you can use the DriveInfo class. using System; using System.IO; class Info { public static void Main() { DriveInfo[] drives = DriveInfo.GetDrives(); foreach (DriveInfo drive in drives) { //There are more attributes you can use. //Check the MSDN link for a complete example. Console.WriteLine(drive.Name); if (drive.IsReady) Console.WriteLine(drive.TotalSize); } } }
I’m surprised: Figure 3 in the middle of this article, The Pathologies of Big Data, says that memory is only about 6 times faster when you’re doing sequential access (350 Mvalues/sec for memory compared with 58 Mvalues/sec for disk); but it’s about 100,000 times faster when you’re doing random access.