Is there any way to run an NBD (Network Block Device) client and server on the same machine without deadlocking the system?
I am very exhausted looking to find an answer for this. I appreciate if anyone can help.
UPDATE:
I'm writing an NBD server that talks to Google Storage system. I want to mount a file system on the NBD and backup my files. I will be hugely disappointed if I have to end up running the server on another machine. Few ideas I already had seem to lead nowhere:
telling the file system to open the block device using O_DIRECT flag to bypass the linux buffer cache
using a raw device (unfortunately, raw devices are character devices and FSes refuse to use them as underlying device)
Just for the record, having the NBD client and server on the same machine has been possible since 2008.
Use a virtual machine (not a container) - you need two kernels, but you don't need two physical machines.
Since the front page of the Sourceforge project for NBD say that a deadlock will happen "within seconds" in this scenario, I'm guessing the answer is a big "No."
Try to write a more complete question of what actual goal you're trying to accomplish. There's some times that you need to bang away at a little problem, and some times that you need to look at the big picture.
Related
I am working for a company that is providing File-Share-Software for all sorts of Protocols such as FTP, SFTP, FTPS and so on. One of our customers is facing an issue with Key-Auth and spontaneously login-problems.
Going trough the code I am pretty certain that the server collapses with too many requests at the same time. What I need right now is a simple tool to test a situation just like this. I need a simple SFTP-Fuzzer or Stresser, sending invalid or broken Auth-Attempts to the SFTP-Server.
I am not a developer but a technician and instead of writing something myself (which would take forever) I would love to have a simple script or toolset to go...if there is one.
Ok, found one faster than I thought.
Steps:
Download Kali Linux (or any Distro that contains Metasploit)
Fire up Kali Linux and put it in the same subnet as your SFTP-Server
Start Metasploit and use the SSH-Fuzzer /auxiliary/fuzzer/ssh/ssh_version_2
Set RHOST and RPORT to the relevant IP and port your server is listening to
Exploit and see what will happen
By reading documents on MSDN, I realized that it is recommended to create separate hosts by functionality (Sending hosts, Receiving hosts and Processing hosts). And if there is only one host in this bizTalk server, this host can perform all receiving, sending, and processing messages functionality.
My question is: Is it possible to have multiple hosts that each host can perform its own sending, receiving and processing function , and not affect each other?
This is for multiple developers working on the same project, because our current situation doesn't allow us to have a full set of SQL Server Database and SQL server for each developer or using VM.
Thanks a lot!
Multiple hosts is not a solution for letting multiple developers work on a single server. A single send/receive adapter can only be assigned to one host.
You will also run into other problems, as all the configuration settings are shared in a single database, a change from 1 developer will effect the others.
This same question was asked and answered at MSDN. What you are trying to do is not supported and will not work. There is no way around this.
You must deploy the same application code to each computer in a BizTalk Group.
Sharing a BizTalk computer for development work is not a workable or productive solution and will have a definite negative affect on productivity.
You are correct, the best way to handle DEV is a VM with the entire stack. This is the issue you must address in your environment.
Hi Guys I'm debugging some CS program and to view the performance of the application in slow internet I tried many different ways. However the best would be the Server and the client be in the same PC ---- my debugging environments for both the server side and the client is setup in one PC.
So I'm wondering is there anyway to limit the speed? I'm using TCP but I don't know too much in-depth knowledge of it.
Thank you
There are two important factors regarding a "slow" internet connection that you need to test out since they have different implications for your application: bandwidth and latency.
If you provide some more details about what os you are running your tests on, it would be easier to recommend a way to limit the network performance.
On a related side note, it's generally a bad idea to performance test any kind of networking using the loopback device on your machine, since many aspects of this will perform very different than the regular network device on your machine.
You mention in the comments this needs to be done on windows, while the Network Emulators I know of (e.g. netem, TCN, other variants) all require Linux. So one thing you could do is create a virtual machine (VirtualBox is fine, I did similar things with it), install linux on it, configure 2 network interfaces, emulate the slow/long/lossy/jittery network between them, and route the test traffic through it from windows.
Finally I found this does what I need.
http://www.nirsoft.net/utils/socket_sniffer.html
Captures Windows Socket traffic, no matter it's local or not.
I have a content management system running on a web server, that among others allows the user to upload assets like images, files, etc to the server.
The problem i have is that there will be 2 servers running behind a load balancer and i am trying to find an efficient way to handle the assets management.
The question i have is:
Will the assets be uploaded to one server every time? Or is there a chance that the images/files will end up into server1 or server2 depending on the load?
How to i serve the images if i don't know on which server they end up in? Will i have to keep the directories of these assets (images/files) synchronized between the two servers?
Thanks,
Synchronization is a tough problem to crack. You can do ad-hoc synchronization using Couchdb but that requires good knowledge of the low-level issues. Therefore you need to choose a write master.
DRDB
You could look at DRDB :D Use one server as the write-master and the other as the slave. Then you can server content from both. This approach is amazing for database-pairs.
Note: seperating your code and URL's for write-master and serve-only will be anoying
Couchdb
You could use couchdb but I think that might be overkill. This is for the LARGE amounts of data and high-levels of fault tolerance.
NFS
You could export the asset directory on the write-master as an nfs drive and import it from the other computer. But in this case it wouldn't be load-balanced in all cases -- i.e., only if the files are cached by the slave. You could use a third computer as an NFS server -- this would allow you to scale to more web-servers.
A central NFS server might just be your best solution as you can do without a write-master as every front-end server can perform writes. This is the approach I would use unless I am thinking of going past the peta-byte range :P
I'm bored cause my development server is down and I'm running the command prompt to ping the server indefinitely so that I'll see when they stop timing out and know that I can work again. In the meantime I wanted to make an Air app that will do this for me, so I can have it chirp or alarm or do something when it starts to be able to connect to the server.
So I need to start with having AIR do the ping, does anyone know how to do this? I can't find any help on it. I can't use the HTTPService because whatever it is that is broken (think it's the VPN), our dev web site is still up.
Thanks
Otherwise you can use the NativeProcess class of the AIR 2.0 beta, and use the ping command of your operating system.
You can find informations on how to use it here.
According to the docs, SocketMonitor, descending from ServiceMonitor will check basic availability, but not a true ping. If you want to truly "ping" the server, you would need to use a socket an implement the protocol, This link to the Wikipedia article might help.
The AIR SDK offers some classes (URLMonitor, SocketMonitor) to handle this:
http://livedocs.adobe.com/flex/3/html/help.html?content=network_connectivity_1.html