My problem is the following:
I usually backup files (e.g. pictures) on external harddisc drives and the store them away in safe places. In the meantime also on NAS. But I don't want to have them connected and online all the time, for power and security reasons.
If I'm now looking for an old file (e.g. a special jpg from the holiday in April 2004) I would have to connect a few discs and search them for the needed file.
To overcome this problem I usually create a recursive dir-dump into a textfile for the whole disc after backup.
This way I can search the filename in the text-file.
But there still is a problem if I don't exactly know the file name that I am looking for. I know the Year and month and maybe the camera I was using then, but there must be hundreds of files in this month.
Therefore I would like to create a "dummy"-backup-filesystem with all the filesnames on the harddisc but without the actual data behind it. This way I could click through the folders and see the foldernames and filenames and easily find the respective file.
The question is: How do I create such a filesystem copy with the complete folderstructures but only the filenames and not the data?
I'm working on Linux, Opensuse, but I guess this is not a linux specific question.
In the meantime I found the solution I was looking for:
Virtual Volume View:
http://vvvapp.sourceforge.net/
Works with Linux, MacOS and Windows!
Related
Our current system database system is a clipper DOS application. The database inside its folder is fragmented/divided into many parts. I want to decrypt the database so that I will have only one database in all and avoid reshuffling of data. I'll attached the file folder Screenshot.. the database is on .DBF format
VScreenshot of files
Often you can decompile the CLIPPER exe file to source code and work from the .prg I've done it many times. The program to use is called WALKYRIE.
In Clipper and Fox Pro for DOS .dbf file is a simple table file.
If You want to use as data base with many tables in one unit.
You can import these tables in MS SQL data base and/or part of a MS Access database.
I see that you got several answers. Most are partially right. Let's address these one at a time:
All those files essentially comprise the "database" for the application you're using. They could be used by other applications as well. Besides having a lot of files, what is the problem you're trying to solve?
People mentioned indexes. You can generally ignore these. There are there primarily to make access to the data files faster. Any properly written clipper application will recreate these if they're missing or corrupted. You could test this by renaming one, running the app, and seeing what happens. If it doesn't recreate it you can name it back. Not replacing missing index files would be unusual behavior.
The DBF file format is binary, but barely. Most of what's in a DBF is text and is readable with an editor. But there's no reason to do so - I'm sure there are several free DBF utilities out there to to read DBF files. Getting the structure of the files could be very helpful.
Getting the data out of the files would also be fairly simple with a utility. If you look up the DBF format you could even write one fairly easily in Clipper, any other language that uses DBF files, or in something like Python. Any language that can open and write files, really. It's not hard - any competent developer could do this in a matter of hours. Must less if you're using Clipper or another language that natively reads DBX files.
Most people create dBase/Clipper programs with relational data, like SQL Server. Where SQL Server has tables that relate to each other dBase/Clipper has a file for each "table." This isn't a requirement, but it was almost certainly done this way.
Given that, if you get the table structures through a utility or by reading the headers in an editor (don't save them from an editor!) you could quite likely recreate the database schema (i.e. the map of the data). Once you have that it's fairly trivial to get the data into another type of database (SQL Sever, Access, or whatever you like to use.) If non of the files are too large it's conceivable to put all the files into Excel sheets. It really depends on what you want to do with it.
As others have said, you may be able to get the code by Valkyrie. Some people have used it very successfully. I don't know where you get it and I've never used it. Why do you not have the code? If this is a commercial application you likely should not have it. If it's a custom app who ever wrote it or paid to have it written should have the code.
Again, it's not clear to me what problem you're trying to solve. But there are many options for doing something with those DBF files. Fortunately they are one of the easier to read data formats you could be working with.
Let me know if you have any questions. Apologies for the typos that are no doubt scattered throughout this reply.
You sort of can get an idea of how they relate to each other by opening the index files they use (.NTX files). If you have the DBU utility (executable) around, you can open the DBF and load the index (NTX). LibreOffice Calc is also able to open DBFs (haven't tested .NTX).
If you open the .NTX on a text editor you will see the indexes in the beginning.
I open with Access, but I can save the data using a PrintFill Program.
I'm developing a change tracking software to monitor files of a specific volume. I tried FileSystemWatcher (.NET) and AlternateDataStreams but they all have some limitations (ie. the change tracking software has to be on 24/7, alternate data streams to not work for ReadOnly files, etc.).
After some investigations I thought that I could directly read the NTFS change journal. This works great if the file is moved/renamed, etc. on the same volume. For identifying the file I'm using the File Reference Number.
But if the file is moved to another volume, the File Reference Number naturally changes.
My question:
Is there a unique ID (GUID or something else) that doesn't change even if the file is moved to another volume?
Well...there can be a file GUID, but it's not there by default.
If you have the necessary permissions, you can race through the files and assign a GUID which will be preserved across NTFS volume moves. Your stated goal is exactly why the feature exists. It uses a somewhat unwieldy API called DeviceIOControl...which is used for a gazillion purposes...but one of it's control codes is FSCTL_CREATE_OR_GET_OBJECT_ID. Check here for details.
It only creates the GUID if one hasn't already been assigned...which is just how you want it to work. Of course, if the file moves to a non-NTFS volume, you're still outta luck.
This question has been asked around several time. Many programs like Dropbox make use of some form of file system api interaction to instantaneously keep track of changes that take place within a monitored folder.
As far as my understanding goes, however, this requires some daemon to be online at all times to wait for callbacks from the file system api. However, I can shut Dropbox down, update files and folders, and when I launch it again it still gets to know what the changes that I did to my folder were. How is this possible? Does it exhaustively search the whole tree in search for updates?
Short answer is YES.
Let's use Google Drive as an example, since its local database is not encrypted, and it's easy to see what's going on.
Basically it keeps a snapshot of the Google Drive folder.
You can browse the snapshot.db (typically under %USER%\AppData\Local\Google\Drive\user_default) using DB browser for SQLite.
Here's a sample from my computer:
You see that it tracks (among other stuff):
Last write time (looks like Unix time).
checksum.
Size - in bytes.
Whenever Google Drive starts up, it queries all the files and folders that are under your "Google Drive" folder (you can see that using Procmon)
Note that changes can also sync down from the server
There's also Change Journals, but I don't think that Dropbox or GDrive use it:
To avoid these disadvantages, the NTFS file system maintains an update sequence number (USN) change journal. When any change is made to a file or directory in a volume, the USN change journal for that volume is updated with a description of the change and the name of the file or directory.
Before I begin, I would like to express my appreciation for all of the insight I've gained on stackoverflow and everyone who contributes. I have a general question about managing large numbers of files. I'm trying to determine my options, if any. Here it goes.
Currently, I have a large number of files and I'm on Windows 7. What I've been doing is categorizing the files by copying them into folders based on what needs to be processed together. So, I have one set that contains the files by date (for long term storage) and another that contains the copies by category (for processing and calculations). Of course this doubles my data each time. Now I'm having to create more than one set of categories; 3 copies to be exact. This is quadrupling my data.
For the processing side of things, the data ends up in excel. Originally, all the data was brough into excel. Then all organization and filtering was performed in excel. This was time consuming and not easily maintainable over the long term. Later the work load was shifted to the file system itself, which lightened the work in excel.
The long and short of it is that this is an extremely inefficient use of disk space. What would be a better way of handling this?
Things that have come to mind:
Overlapping Folders
Is there a way to create a folder that only holds the addresses of a file, rather than copying the file. This way I could have two folders reference the same file.
To my understanding, a folder is a file listing the memory addresses of the files inside of it, but on Windows a file can only be contained in one folder.
Microsoft SQL Server
Not sure what could be done here.
Symbolic Links
I'm not an administrator, so I cannot execute the mklink command.
Also, I'm uncertain about any performance issues with this.
A Junction
Apparently not allowed for individual files, only folders in windows.
Search folders (*.search-ms)
Maybe I'm missing something, but to my knowledge there is no way to specify individual files to be listed.
Hashing the files
Creating hash tags for all the files, would allow for the files to be stored once. But then I have no idea how I would handle the hash tags.
XML
Maybe I could use xml files to attach meta data to the files and somehow search using them.
Database File System
I recently came across this concept in my search. Not sure how it would apply Windows.
I have found a partial solution. First, I discovered that the laptop I'm using is actually logged in as Administrator. As an alternative to options 3 and 4, I have decided to use hard-links, which are part of the NTFS file system. However, due to the large number of files, this is unmanageable using the following command from an elevated command prompt:
mklink /h <source\file> <target\file>
Luckily, Hermann Schinagl has created the Link Shell Extension application for Windows Explorer and a very insightful reading of how Junctions, Symbolic Links, and Hard Links work. The only reason that this is currently a partial solution, is due to a separate problem with Windows Explorer, which I intend to post as a separate question. Thank you Hermann.
While building web applications often we have files associated with database entries, eg: we have a user table and each category has a avatar field, which holds the path to associated image.
To make sure there are no conflicts in filenames we can either:
rename files upon upload to ID.jpg; the path would be then /user-avatars/ID.jpg
or create a sub-directory for each entity, and leave the original filename intact; the path would be then /user-avatars/ID/original_filename.jpg
where ID is users's unique ID number
Both perfectly valid from application logic's point of view.
But which one would be better from filesystem performance point of view? We have to keep in mind that the number of category entries can be very high (milions).
Is there any limit to a number of sub-directories a directory can hold?
It's going to depend on your file system, but I'm going to assume you're talking about something simple like ext3, and you're not running a distributed file system (some of which are quite good at this). In general, file systems perform poorly over a certain number of entries in a single directory, regardless of whether those entries are directories or files. So no matter whether if you're creating one directory per image or one image in the root directory, you will run into scaling problems. If you look at this answer:
How many files in a directory is too many (on Windows and Linux)?
You'll see that ext3 runs into limits at about 32K entries in a directory, far fewer than you're proposing.
Off the top of my head, I'd suggest doing some rudimentary sharding into a multilevel directory tree, something like /user-avatars/1/2/12345/original_filename.jpg. (Or something appropriate for your type of ID, but I am interpreting your question to be about numeric IDs.) Doing that will also make your life easier later when you decide you want to distribute across a storage cluster, since you can spread the directories around.
Millions of entries (either files or directories) in one parent directory would be hard to deal with for any filesystem. While modern filesystems use sorting and various tree algorithms for quick search for the needed files, even navigating to the folder with Windows Explorer or Midnight Commander or any other file manager will be complicated as the file manager would have to read contents of the directory. The same applies to file search. So subdirectories are preferred for this.
Yet I need to notice that access to particular file would be a bit faster when all files are in one directory than when they are separated into subdirectories at least on NTFS (measured this myself several times with 400K files).
I've been having a very similar issue with html files not images. Trying to store millions of them in a Ubuntu server in ext4. Ended running my own benchmarks. Found out that flat directory performs way better while being way simpler to use:
Reference: article
If you really want to use files, maybe your best bet is to partition the files off into several subdirectories so that you don't hit a limit. For example, if you have an ID 123456, you can put it in /12/34/56.jpg.
However, I would recommend just using the database to store this data since you are already using one. You can store the image data and ID in the same table, and you don't have to worry about some of the pesky business of dealing with files like making sure the permissions are set right, etc.