I&#39;m currently designing an architecture for a web-based application that should also provide some kind of image storage. Users will be able to upload photos as one of the key feature of the service. Also viewing these images will be one of the primary usages (via web). 

However, I&#39;m not sure how to realize such a scalable image storage component in my application. I already thought about different solutions but due to missing experiences, I look forward to hear your suggestions. Aside from the images, also meta data must besaved.
Here are my initial thoughts:

1. Use a (distributed) filesystem like HDFS and prepare dedicated webservers as &quot;filesystem clients&quot; in order to save uploaded images and service requests. Image meta data are saved in a additional database including the filepath information for each image. 

2. Use a BigTable-oriented system like HBase on top of HDFS and save images and meta data together. Again, webservers bridge image uploads and requests. 

3. Use a completly schemaless database like CouchDB for storing both images and metadata. Additionally, use the database itself for upload and delievery by using the HTTP-based RESTful API. (Additional question: CouchDB does save blobs via Base64. Can it however return data in form of image/jpeg etc.)?  


Scalable Image Storage

I want to use `.data()` in my application. The [examples][1] are helpful, but I do not understand however where the values are stored.

I inspect the webpage with Firebug and as soon as .data() saves an object to a dom element, I do not see *any* change in Firebug (either HTML or Dom tabs).

I tried to look at jQuery source, but it is very advanced for my Javascript knowledge and I lost myself.

So the question is:

Where do the values stored by jQuery.data() actually go? Can I inspect/locate/list/debug them using a tool?



  [1]: http://api.jquery.com/jQuery.data/

How does jQuery .data() work?

With jQuery you can bind functions to an event triggered on a DOM object using `.bind()` or one of the event handler helper functions.

jQuery have to store this internally somehow and I wonder if is it possible given a DOM object, to find out which events have been bound to the object, and access those functions etc. The desired return result could look something like this:

    {
      click: [function1, function2],
      change: [function3],
      blur: [function4, function5, function6]
    }

Accessing functions bound to event handlers with jQuery

Is there any way to store values other than strings with AsyncStorage? I want to store simple boolean values for example.

    AsyncStorage.setItem(&#39;key&#39;, &#39;ok&#39;);

Is no problem, but:

    AsyncStorage.setItem(&#39;key&#39;, false);

Does not work..

React Native AsyncStorage storing values other than strings

I&#39;m working on a database for a small web app at my school using `SQL Server 2005`.  
I see a couple of schools of thought on the issue of `varchar` vs `nvarchar`:

 1. Use `varchar` unless you deal with a lot of internationalized data, then use `nvarchar`.
 2. Just use `nvarchar` for everything.

I&#39;m beginning to see the merits of view 2.  I know that nvarchar does take up twice as much space, but that isn&#39;t necessarily a huge deal since this is only going to store data for a few hundred students.  To me it seems like it would be easiest not to worry about it and just allow everything to use nvarchar.  Or is there something I&#39;m missing?

What are the main performance differences between varchar and nvarchar SQL Server data types?

Lately I have been using GitHub and I am wondering what is the repository size limit for files hosted on github.com?  I have been wondering this because I was thinking of using GitLab, since it allows 10 GB for each repository.

Repository size limits for GitHub.com

If I want to store the username and password to be used inside an Android application, what is the best way to do it? Is it through the preferences screen (but what if the user misses this?), or pop up a dialog box and ask the user for the credentials? If so, I do have to maintain state for the application. How would I do this?

Android: Storing username and password?

I have two machines, speed and mass. speed has a fast Internet connection and is running a crawler which downloads a lot of files to disk. mass has a lot of disk space. I want to move the files from speed to mass after they&#39;re done downloading. Ideally, I&#39;d just run:

    $ rsync --remove-source-files speed:/var/crawldir .

but I worry that rsync will unlink a source file that hasn&#39;t finished downloading yet. (I looked at the source code and I didn&#39;t see anything protecting against this.) Any suggestions?

keep rsync from removing unfinished source files

I am developing a mobile web application (for iPhone &amp; Android) with a local database (using html5 webstorage) so my app is still usable when the user is offline.

This is working perfectly, but I want to save the local data on a server. So I need to synchronize the local DB with a DB on a server. The synchronisation can only be one way, but in the future, I would like to synchronize it in the both way (server &lt;-&gt; local DB).

This requierement looks very common (or will be common in the future for mobile web app), but I can&#39;t find a library doing that.

I know google is doing that in their mobile web app (ex. gmail), and I found the [WSPL project][2] a google project but without source to download.


If I can&#39;t find a solution, I will create a library to do that, as one way sync doesn&#39;t look difficult, but I wonder if there are other solutions.


  [2]: http://ajaxian.com/archives/web-storage-portability-layer-abstract-on-top-of-html5-and-gears-storage

Best way to synchronize local HTML5 DB (WebSQL Storage, SQLite) with a server (2 way sync)

I would like to know how much space does my MySQL database use, in order to select a web host.
I found the command `SHOW TABLE STATUS LIKE &#39;table_name&#39;` so when I do the query, I get something like this:

    Name       | Rows | Avg. Row Length | Data_Length | Index Length
    ----------   ----   ---------------   -----------   ------------
    table_name   400          55            362000        66560

* numbers are rounded.

So do I have **362000**  or 400*362000 = **144800000** bytes of data for this table?
And what does Index Length mean?
Thanks !

How to Get True Size of MySQL Database?

Can someone explain what the `transient` and `volatile` modifiers mean in Java?


What are Transient and Volatile Modifiers?

What is the difference between persistent volume (PV) and persistent volume claim (PVC) in Kubernetes/ Openshift by referring to documentation?

What is the difference between both in simple terms?


What is the difference between persistent volume (PV) and persistent volume claim (PVC) in simple terms?

1. What is the key difference between IOPS and Throughput in large data storage?
2. Does file size have an effect on IOPS? Why?

IOPS versus Throughput

I&#39;m looking for the amount of storage in bytes (MB, GB, TB, etc.) required to store a single human genome. I read a few articles on Wikipedia about DNA, chromosomes, base pairs, genes, and have some rough guess, but before disclosing anything I&#39;d like to see how others would approach this issue.

An alternative question would be how many atoms are there in human DNA, but that would be off topic for this site.

I understand that this will be an approximation, so I&#39;m looking for the minimal value that would be able to store DNA of any human.

How much storage would be required to store a human genome?

I am using 1.2.5 with a standard ImageField and using the built-in storage backend. Files upload fine but when I remove an entry from admin the actual file on the server does not delete.

How do I get Django Admin to delete files when I remove an object from the database/model?

I have a little issue with creating a directory and saving a file to it on my android application. I&#39;m using this piece of code to do this :

	String filename = &quot;MyApp/MediaTag/MediaTag-&quot;+objectId+&quot;.png&quot;;
	File file = new File(Environment.getExternalStorageDirectory(), filename);
	FileOutputStream fos;
	
	fos = new FileOutputStream(file);
	fos.write(mediaTagBuffer);
	fos.flush();
	fos.close();

But it&#39;s throwing an exception :

&gt; java.io.FileNotFoundException: /mnt/sdcard/MyApp/MediaCard/MediaCard-0.png (No such file or directory)

on that line : `fos = new FileOutputStream(file);`
 
If I set the filename to : `&quot;MyApp/MediaTag-&quot;+objectId+&quot;` it&#39;s working, but If I try to create and save the file to an another directory it&#39;s throwing the exception. So any ideas what I&#39;m doing wrong?

And another question: Is there any way to make my files private in external storage so user can&#39;t see them in gallery, only if he connect his device as `Disk Drive`?

Android saving file to external storage

Generally, how bad of a performance hit is storing a file in a database (specifically mssql) as opposed to the file system?  I can&#39;t come up with a reason outside of application portability that I would want to store my files as varbinaries in SQL Server.

Storing a file in a database as opposed to the file system?

I am creating an app using the Bespin editor and HTML5&#39;s localStorage. It stores all files locally and helps with grammar, uses JSLint and some other parsers for CSS and HTML to aid the user.

I want to calculate how much of the localStorage limit has been used and how much there actually is. **Is this possible today?** I was thinking for not to simply calculate the bits that are stored. But then again I&#39;m not sure what more is there that I can&#39;t measure myself.

Calculating usage of localStorage space

I have a table in pg like so:

    CREATE TABLE t (
        a BIGSERIAL NOT NULL,               -- 8 b
        b SMALLINT,                         -- 2 b
        c SMALLINT,                         -- 2 b
        d REAL,                             -- 4 b
        e REAL,                             -- 4 b
        f REAL,                             -- 4 b
        g INTEGER,                          -- 4 b
        h REAL,                             -- 4 b
        i REAL,                             -- 4 b
        j SMALLINT,                         -- 2 b
        k INTEGER,                          -- 4 b
        l INTEGER,                          -- 4 b
        m REAL,                             -- 4 b
        CONSTRAINT a_pkey PRIMARY KEY (a)
    );
    
The above adds up to 50 bytes per row. My experience is that I need another 40% to 50% for system overhead, without even any user-created indexes to the above. So, about 75 bytes per row. I will have many, many rows in the table, potentially upward of 145 billion rows, so the table is going to be pushing 13-14 terabytes. What tricks, if any, could I use to compact this table? My possible ideas below ...

Convert the `real` values to `integer`. If they can stored as `smallint`, that is a saving of 2 bytes per field.

Convert the columns b .. m into an array. I don&#39;t need to search on those columns, but I do need to be able to return one column&#39;s value at a time. So, if I need column g, I could do something like

    SELECT a, arr[5] FROM t;
    
Would I save space with the array option? Would there be a speed penalty?

Any other ideas?

Calculating and saving space in PostgreSQL

So I&#39;m using an app that stores images heavily in the DB. What&#39;s your outlook on this? I&#39;m more of a type to store the location in the filesystem, than store it directly in the DB.

What do you think are the pros/cons?          

Storing Images in DB - Yea or Nay?

I looked around and found some of the MySQL engines are innodb and MyISAM. Perhaps there are few more. My question is what are these database engines?

What are the differences between different MySQL engines? And more importantly, How do I decide which one to use?

What are MySQL database engines?

The [documentation][1] says that `CharField()` should be used for smaller strings and `TextField()` should be used for larger strings.  

Okay, but where is the line drawn between &quot;small&quot; and &quot;large&quot;?  What&#39;s going on under the hood here that makes this the case?


  [1]: https://docs.djangoproject.com/en/1.10/ref/models/fields/#django.db.models.CharField

What&#39;s the difference between CharField and TextField in Django?

As per the title of this question, what are the practical differences between AWS EFS, EBS and S3?

My understanding of each:

- S3 is a storage facility accessible any where
- EBS is a device you can mount onto EC2
- EFS is a file system you can mount onto EC2

So why would I use EBS over EFS? Seem like they have the same use cases but minor semantic differences? Although EFS is replicated across AZs where as EBS is just a mounted device. I guess my understanding of EBS is lacking hence I&#39;m unable to distinguish. 

Why choose S3 over EFS? They both store files, scale and are replicated. I guess with S3 you have to use the SDK where as with EFS being a file system you can you standard I/O methods from your programming language of choice to create files. But is that the only real difference?

AWS EFS vs EBS vs S3 (differences &amp; when to use?)

When I installed Windows XP on a **VirtualBox** machine, I made the hard drive only **10 GB** since and assumed it would **expand** in size (as do hard drives in **VMWare** as far as I can remember, isn&#39;t this true?).

In any case, I&#39;m trying to install Visual Studio 2010 beta on this Virtual Box XP image and it has **run out** of disk space.

Googling for an answer, I&#39;m finding **complicated [tutorials like this][1]** which show you how to increase the size of a VirtualBox hard drive &quot;in just a **couple hours**&quot;. 

But I can&#39;t imagine it would be that hard to either:

- **increase the size** of a virtual disk (after all, it *is* virtual)
- **create** a new hard drive of, say, 20 GB and just **attach** it in the virtual machine as the D: or E: drive

**How can I easily add storage space to a VirtualBox machine with XP installed?**



  [1]: http://www.giannistsakiris.com/index.php/2007/11/25/how-to-enlarge-a-virtualbox-disk/

How can I easily add storage to a VirtualBox machine with XP installed?

I have a simple Xamarin Forms app. I&#39;ve now got a simple POCO object (eg. `User` instance or an list of the most recent tweets or orders or whatever).

How can I store this object locally to the device? Lets imagine I serialize it as JSON.

Also, how secure is this data? Is it part of Keychains, etc? Auto backed up? 

cheers!

How can I save some user data locally on my Xamarin Forms app?

I want to store a hashed password (using BCrypt) in a database. What would be a good type for this, and which would be the correct length? Are passwords hashed with BCrypt always of same length?

**EDIT**

Example hash:

`$2a$10$KssILxWNR6k62B7yiX0GAe2Q7wwHlrzhF3LqtVvpyvHZf0MwvNfVu`

After hashing some passwords, it seems that BCrypt always generates 60 character hashes.

**EDIT 2**

Sorry for not mentioning the implementation. I am using [jBCrypt][1].


  [1]: http://www.mindrot.org/projects/jBCrypt/

What column type/length should I use for storing a Bcrypt hashed password in a Database?

I am building a form in which I have to store the data in HTML5&#39;s `sessionStorage` I don&#39;t know when the `sessionStorage` expires. Can anyone tell me about the expiration time of the `sessionStorage`?

All Storage Solutions on Gang of Coders

Total of 27 Storage Solutions