Krishna Ganugapati’s Weblog

Short post: I was recently interviewed by http://www.HowSoftwareisBuilt.com.

This one is another short post. Here are our highlights

1) Share management is fully operational: This means you can launch MMC from your Windows client; load up the share management snapin and point to Linux box running the lwio SMB file server and srvsvc daemon. The result is that you can browse shares from a Windows client; you can create a new share on your Linux server as well and do all of the file share operations. We have yet to complete the “open files” and “open sessions” functionality. But we’re so pleased with seamless management that we’ve punted on this for now.
2) Our Likewise FuSE driver is fully operational: This means that a Linux client joined to Active Directory can easily mount SMB shares on a Windows/Samba/Likewise SMB file server. Here is the cool part: you login on your Linux machine using your Active Directory credentials and single sign-on mount your SMB file share. If your machine is multi-user and simultaneously your buddy logs on to the same machine and mounts his SMB file share using our FuSE driver; he connects seamlessly with his credentials to the SMB server. This is a really elegant piece of work. Brian tells me that OpenOffice running on a Linux client can save files to a Likewise/Samba/Windows SMB File Server through our SMB redirector. As you can notice, I am getting a kick out of saying Likewise/Samba/Windows SMB File Server. The cool thing here is not the file server, it is our FuSe driver that calls our SMB redirector (file client) within the LWIO Framework.

3) A ton of other coolness; I thought I’d just copy Jerry’s mail to me

“What works:

* User profiles load from the network
* Home directories mount properly at login time.
* My Documents redirection to %HOMESHARE%\%HOMEPATH%\Documents
works fine.

Also ran some tests with iTunes and was able to successfully import and existing library XML file and 4k mp3s from a network share to my current iTunes library. So now all my music is being served (and playing 24×7) from our server. Also editing mp3 song properties (artist, genre, etc…) works properly.

What is not working:

* Take ownership of files fails
* Roaming profiles are not saving

I believe that both of these are due to the lack of properly support partial security descriptor set operations (based on the SECURITY_INFORMATION flags) which I will implement today.”

I’ll post some screenshots once I get some cycles…

Thanks for reading!

This is a really short post, but I hope people get a kick out of it. Here is the current set of applications that the SMB server supports. This means an Windows XP client can run the applications below, read files from and write files to a file share on Linux machine running the Likewise SMB Server!

1) Word
2) Excel
3) Powerpoint
4) Explorer
5) IE
6) cmd shell
7) Tortoise SVN for checkouts
Visio
9) Project
10) Wireshark
11) Notepad
12) Outlook
13) Firefox
14) Safari
15) iTunes
16) Adobe Reader
17) Publisher
18) OpenOffice.org
19) QuickTime
20) Software Extraction and Installation/.MSI files all work
21) Image Previews and Thumbnails

Thanks for reading!

One of the more painful things about using Linux as a client in a Windows corporate intranet is the clunkiness of integration. The most basic requirement is that you be able to bring up the Nautilus or your favorite graphical file browser and browse through files that live on a Windows (Samba) file server. I’ll reiterate: this is one of the most basic requirements.

Now most affficianados will be up in arms when I say this. Of course, Linux does this and Ubuntu does this out of the box. But here is the rub: Ubuntu’s Nautilus file browser will does this fine. But now I want to go to my bash command shell and I want it to also be able to browse to my Windows file shares. This does not happen out of the box.

Now even if you get all of the pieces to work, the credentials are messed up. The single-sign-on experience needs to immediately transfer itself to all client applications. Even though you can sign in with your AD credentials, if I have to re-enter my credentials, it adds to the clunkiness of the experience.

Introducing the SMB redirector in lwio.

Our SMB redirector driver provides all of the semantics necessary for a file client API. The obvious next step was to pick up FUSE and begin work on a FUSE driver that would call our lwio APIs – NtCreateFile, NtReadFile, NtWriteFile, NtClose. Once you provide a FUSE driver to our SMB client, automatically, a client can mount smb shares without reentering his/her credentials. Once the client mounts a share, he can browse the directory space, copy files, move files, create directories, delete files and perform every UNIX file system operation against the SMB volume. Even better, Nautilus and the Gnome shell work without any additional work.

We’ve started construction of this FUSE driver and its is amazing how fast we’re putting together the pieces. Our Posix Virtual File System (which is the most complete lwio driver) is proxying for the SMB Redirector File System (we’ve implemented enough for the named pipe interface and its missing some of the QueryInfo and SetInfo semantics)

Now here is the even more interesting part: FUSE driver run as a daemon themselves, so a client (like the shell) has to communicate to the FUSE daemon which in turn communicates to the lwio daemon. That’s a transition of 2 processes which means at least 4 context switches to service a call. But lwio can implement a FUSE driver as another lwio driver. Just like the SMB server driver calls the IO Manager to route requests to the Posix Virtual File System, the FUSE lwio driver calls the IO Manager to route requests to the SMB Redirector File System. This implies we reduce the number of context switches between processes to half what we would have if we ran FUSE independently as a separate daemon. This was Brian Koropoff’s epiphany over the weekend. We’re still going to do this first as a separate daemon, iron out the end-to-end scenario, but then placing it into the lwio kernel is a natural optimization.

Well, I thought we’d be doing three key scenarios by April 15th. It looks like we’re going to go for a fourth scenario.

Thanks for reading!

In the course of building a new software system, there are these inflection points when everything comes together. Last week was one such inflection point. Here are the highlights
- Windows explorer, dir, Acrobat reader, thumbnails views on explorer all work
- copying files, deleting files, drag and drop, xcopies are all smooth and seamless
- Word now works – we can click on a Word document on a share and we can open the document and edit it
- Multiple connections and multiple large file downloads work smoothly
- We’ve set up an internal file server that hosts over half a terrabyte of data (with full iso OS images and VMs) and are using this as our internal dog food server.
- The MMC share management snapin and wizard works smoothly; we can point MMC at our Linux server create, delete and manage shares on the server.
- The installation is very simple. There is next to nothing to configure and setup. Install the bits and you have a file server available.

The month of March promises to be very interesting for us. I’ll write another post on what we plan on accomplishing by end of March.

Thanks for reading