Backup Azure Virtual Machine local folders to blob storage? - azure

I've just setup an extra small VM instance in Windows Azure to run a help console for our company. The help files can be updated and published through a simple .NET interface. Obviously the flat html files are getting deployed to the local drive on the VM and exposed publicly through IIS. I'm just wondering how stable this is? If the VM suffers a hardware failure, presumably there's no automatic failover and any edits we've made to the help system will be lost?
Can anyone recommend a way I can shuttle the source files out of the VM into blob storage? I could write a an application to do this, I'm just wondering if there is an out-of-the-box solution out there?
Additional information:
The VM instance is running Server 2008 R2 SP1 (As a Virtual Machine not a web-role)
A backup needs to be created once every 24 hours
Aged backups (3+ days old) need to be automatically cleared from the blob container
The help system we use is called HelpConsole 2012
New pages are added at a rate of myabe 2-3 per week

The answer depends on how whether you are running this in a Windows Azure Virtual Machine or on a Windows Azure Web role.
If you are running this on a Windows Azure Virtual Machine, then the VHD is stored in BLOB storage and, if the site is running of the C: drive and not on a data Disk, then the system has some Host caching turned on for both reads and writes. In this scenario it is possible (depending on the methods you use to write your files out) that the data is not pushed back to the VHD in BLOB storage before a failure occurs. You can either ensure that your writing methods do a write through operation, or turn off the write caching. Better yet, attach a data disk for your web site files. By default data disks have both read and write caching off (you could turn on read caching). Since the VHD's are persisted you don't have to worry about the concern of the edits getting lost. You can script out taking a snapshot of the files and move them to BLOB storage separately, or even push them somewhere else. Another thing to think about with this option is that you have to care for the VM instances and keep them patched and up to date.
If you are running a Web Role, then yes, if a failure occurs and the VM goes through self healing it will indeed redeploy with the older files. In this case I'd recommend changing the code in the web role that when it writes the updates to the local file it also puts a copy of the local file into BLOB Storage. In addition, in the web role OnStart you could reach out to BLOB storage and pull down all the new content locally. BE VERY CAREFUL with this approach though because it only really works well for ONE instance, not multiple. If you plan on running multiple instances of the server (and you will have to if you want the SLA for uptime) then your code will need to be a little more robust and do writes out to BLOB storage and then alert all instances of the role that there is a new file to pull down locally.
Another option for web roles is to also write a handler for the content so that requests come in and are mapped to a file BLOB Storage directly. Then updates can occur to direct edits to the file in BLOB storage. This offloads the serving of the flat files from your compute nodes to BLOB storage and you could even implement some caching and stream the content back through the handler rather than having them hit BLOB storage directly if you wanted to.
Now, another option, is to use Windows Azure Web Sites for this. The underlying storage of the web site files in Windows Azure Web Sites is a shared location and thus updating the files in it will immediately be reflected for all instances. Also, the content for the site is stored in BLOB storage and can be updated via FTP, source control, or directly from code. Lots of options here. You may end up moving to reserved instances to help keep away from some of the quotas that Web Sites have. Web Sites may not be an option for you currently depending on other requirements (as in how much control do you need over the environment since you don't get a lot of control for Web Sites).

Related

Do I need Azure blob storage or just a simple web server on a VM?

I have a VM on Azure which is my content management system using nodejs and mongodb.
One of things the CMS does is have a social sharing function where html pages are created and users are given the url to this page.
I expect a large volume of users (probably 5000 at a given time) access the http pages. I do not want this load to be on the same server as my CMS.
So I was thinking about moving the html pages to another server. My question is do I need to look at Azure blob storage to do this or should I just use another VM and put files there?
The files are very small and minified. I want to keep my costs down whilst at the same time if I get more than 5000 requests, the server should auto scale.
The question itself is somewhat subjective/opinion-soliciting. And how you solve this problem is really up to you.
But from an objective perspective:
Blobs themselves are not the same as local file storage. If you're going to store content in them, either your CMS needs to support them natively or you're going to need to build that support into it (if that's even possible). Since they have their own REST API (and related SDKs) you cannot simple do file I/O operations against them. They are, however, accessible via URI (which may be made private or public).
Azure VMs store their disks (vhd's) in page blobs (so, you're already using blob storage technically speaking). And each VM may have attached disks (1TB each) also in page blobs, two disks per core (so a dual-core VM supports 4 attached 1TB disks). Just like your OS disk, these attached disks are durable, in blob storage. A CMS may access an attached disk once it's formatted and given a drive letter (Windows) or mounted (Linux). EDIT - forgot to mention: If you go with the attached-disk approach, you need to consider the fact that these disks are per-VM. That is, they are not shared across multiple VM's (in the event you scale your CMS to multiple instances).
Azure File Service is an SMB share sitting atop Azure Blob Storage. Again, durable storage, and drive-mappable. EDIT unlike attached disks, Azure File Service SMB shares are accessible across multiple VM's.

Backup Microsoft Azure Virtual Machine

I currently have a Rackspace Cloud Server that I'd like to migrate to an Azure Virtual Machine. I recently got an MSDN subscription which gives me a certain level of hosting via Azure at no cost, where I'm currently paying for that level of service with Rackspace.
However, one of the nice things about Rackspace is that I can schedule nightly/weekly backups of the VM image. Is there any mechanism for doing this on Azure? I'm worried about protecting against corruption of the database (i.e. what if someone were to run an UPDATE statement and forget the WHERE clause). Is there a mechanism for this with Azure?
I know the VMs are stored as .VHD files in my local Azure storage, but the VM image is 127 gigs. Downloading that nightly even with FIOS internet isn't really going to fly as a solution.
You can perform an asynchronous blob copy to make a physical copy of a vhd. See here for REST API details. This operation is very fast within the same data center (maybe a few seconds?). You don't need to make raw REST calls though: There's a method already implemented in the Azure cross-platform command line interface, available here. The command is:
azure vm disk upload
You can also take blob snapshots, and return to a previous snapshot later. A snapshot is read-only (which you can copy from later) and takes up no space initially. However, as storage pages are changed, the snapshot grows.
One question though: why such a large VM image? Are you storing OS + data on same vhd? If so, it may make more sense to mount a separate Azure Drive (also stored in VHD in blob storage) to store data, and make independent copies / snapshots.

Azure Architecture Design

I'm new to Azure, and a little confused about blob storage. I have a need for clients to access via FTP / SFTP to push and pull files (XML, CSV, EDI, etc). The pushed files are read in by a .net application and written to a database. As I understand, we would use a VM role to create a FTP / SFTP server, a worker role to execute the .net code, SQL Storage for the DB and Blob storage for the files.
Am I correct in this assumption first, and second can a VM role attach a storage blob for writing and reading files and can a worker role attach to the same storage blob to read and write files as well.
Sample:
client pushed xml file to VM via FTP. VM writes XML file to storage. Worker role reads file, processes it and writes contents to db.
Is my thinking correct or am I missing the boat?
Thanks
Given Azure has an array of services so you have a few options. One important thing to keep in mind with Azure is that your worker roles, which are simply Windows Server 2008 without IIS installed, are very flexible so there is a lot you can do with them – this includes writing your own FTP server and being able to host it via a worker role VMs. The FTP to Azure Blob Storage Bridge (on CodePlex) solution is an example of this.
In addition, you could use a web role (which is the same as a worker role but with IIS enabled) to do the same - so rather than rolling your own FTP server you can use IIS. A visual guide to setting IIS up to run as an FTP server in Azure can be found on ITQ.
I’d recommend doing some further reading to determine which is the better option of the two. Also have a think about you requirements as this may influence your approach, i.e. scaling, bandwidth, costs, your preferred deployment model etc.
As far as storing the files goes you can certainly use Blob Storage. If you have no need for a relational database in your system then you could skip using SQL Azure altogether (in which case the web role solution referenced above won’t be of much use) – but again that comes down to your particular requirements.
The official Windows Azure website is a good source of knowledge, especially if you’re getting started, so do take the time to look through some of the pertinent documentation.

How to write to a tmp/temp directory in Windows Azure website

How would I write to a tmp/temp directory in windows azure website? I can write to a blob, but i'm using an NPM that requires me to give it file names so that it can directly write to those filenames.
Are you using Cloud Services (PaaS) or Virtual Machines (IaaS).
If PaaS, look at Windows Azure Local Storage. This option gives you up to 250gb of disk space per core. Its a great location for temporary storage of information in a way that traditional apps will be familiar with. However, its not persistent so if you put anything there you need to make sure will be available if the VM instance gets repaved, then copy it to Blob storage. Also, this storage is specific to a given role instance. So if you have two instances of the same role, they each have their own local storage buckets.
Alternatively, you can use Azure Drive, which allows you to keep the information persisted, but still doesn't allow multiple parallel writes.
If IaaS, then you can just mount a data disk to the VM and write to it directly. Data disks are already persisted to blob storage so there's little risk of data loss.
Just from my understanding and please correct me if anything wrong.
In Windows Azure Web Site, the content of your website will be stored in blob storage and mounted as a drive, which will be used for all instances your web site is using. And since it's in blob storage it's persistent. So if you need the local file system I think you can use the folders under your web site root path. But I don't think you can use the system tmp or temp folder.

Azure WCF accessing disk files

I have a WCF service hosted on Windows Azure as a "cloud service." When the service starts, it needs to populate data from files/disk to its memory so it is accessed fast (cached in other words). Right now I'm using like C:\Documents\Filestoprocess folder so that the WCF calls the folder and populates data data in that folder in its memory. I have like 5,000 small files. How do I do this in Azure? Is there a folder path that I can call within the WCF so that the WCF calls these files and opens each files and saves each data in the files? I'm not really looking for complicated Blob access through network using bandwidth. I'm looking for simple disk I/O access to these files from the WCF "cloud service" that is running on its own public web address.
You should try to use a cloud storage service to store data, as if you write to the local file system it can get destroyed on a restart of the service or recycling of the service.
You can look into using the azure drive service, which is like creating a disk dive. It is on top of blob storage.
But if you really want to write and read data on the local file system check out this blog post http://blog.codingoutloud.com/2011/06/12/azure-faq-can-i-write-to-the-file-system-on-windows-azure/
It talks about setting up your service definition to allow writing to the local file system.
Depending on the size of your instances you'll get a non-presistent disk where you can store this kind of temporary data. The minimum is 20GB for an extra small instance. You shouldn't access the disk directly, but you need to use a local resource instead which you can configure in your service definition file or in Visual Studio (double click your Web / Worker Role).
This storage is non-persistent, this means if you delete your deployment, if you decrease the number of instances, in case of hardware problems, ... you loose all data saved here. If you want to persist your files you should use blob storage instead. But in your case, where you need the files as some kind of caching mechanism, local resources are perfect.
And if your goal is to cache data you might want to take a look at the caching features included in Windows Azure: Caching in Windows Azure
Blob access is not complex. In fact, you could do a single download of a zip file from blob storage to local disk, unzip it, then prime your wcf service from those 5,000 small files.
Check out this msdn page documenting DownloadBlobToFile(). The essential parts:
CloudBlobClient blobClient =
new CloudBlobClient(blobEndpoint, new StorageCredentialsAccountAndKey(accountName, accountKey));
// Return a reference to the blob.
CloudBlob blob = blobClient.GetBlobReference("mycontainer/myblob.txt");
// Download the blob to a local file.
blob.DownloadToFile("c:\\mylocalblob.txt");
Now: I don't agree with saving to the root folder on C:. Rather, you should grab some local storage (easily configurable). Once you configure local storage in your role configuration, just ask the role environment for it, and ask for root path:
var localResource = RoleEnvironment.GetLocalResource("mylocalstorage");
var rootPath = localResource.RootPath;
Note: As #KingPancake mentioned, you could use an Azure drive. However: remember that an Azure drive can only be writeable by one instance. You'd need to make additional snapshots for your other instances. I think it's much simpler for you to go with a simple blob, copy your files down (either as single zip or individual files), and go from there.
You mentioned concern with network+bandwidth. You don't pay for bandwidth within the same data center. Also: It's extremely fast: 100Mbps per core. So even with a Small instance, you'll have your files copied down very quickly, moreso when you go to larger instance sizes.
One last thought: The only other ways to gain access to your 5,000 files, without using blob storage or Azure Drives (which are mounted as vhd's in blob storage) would be to either download the files from an external source or bundle them with your Windows Azure package (and then they'd show up in your app's folder, under whatever subfolder you stuck them in). Bundling has two downsides:
Longer time to upload your deployment package due to added size
Inability to change any of the individual files without redeploying the package.
By storing in a blob, you can easily change one (or all) of your small files without redeploying your code - you'd just need to signal it to either re-read from blob storage or restart the instances so they automatically download the new files.

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