Re: Files, unloving, access, oh my.
> Why do you feel files are so unloved? :) Why was Ken unliking his files? I just went a step in the wrong direction. :-) It looks like my original reply didn't copy to the list due to me sending from my other Email account. So, one more time: From: Ben Scott > On Tue, Feb 19, 2013 at 2:40 PM, Ken D'Ambrosio wrote: > > If process A is reading from a file, and process B deletes it, process > > A can continue to read from it until... well, until it stops reading > > from it. > Remember, in *nix, one doesn't really delete files (inodes). One > unlinks directory entries. The kernel deletes files once all > references are gone. Well, FS writers generally keep the link count and open count separate entities, largely because they are. Then there's a separate "ref count" for all the kernel threads that are mucking with the kernel data structures for that inode. That's usually incremented when the file is opened so the kernel doesn't have to check the open count. (The process has a file struct for each open file, hence holds a ref for that pointer.) When the ref count is requested to drop to zero then the open count should be zero, and if the link count is zero then the inode is freed. The kernel data structures are freed, and by then there's no ref count left to decrement to zero. > One of the things fsck does is check for inodes with a zero actual > reference count, and link them in "lost+found" by inode number. More precisely, given that the FS is unmounted when fsck is willing to make changes, nothing has the file open, let alone reffed, so the link count is the sole test, well, if there are indeed no directory entries linking to the file. If there are, that means the inode was written before a directory block without the directory entry to the file was written, so fsck will update the directory too. -Ric -- r...@wermenh.comhttp://WermeNH.com/ ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
Re: Files, unloving, access, oh my.
On Wed, Feb 20, 2013 at 8:59 AM, Ric Werme wrote: >> Remember, in *nix, one doesn't really delete files (inodes). One >> unlinks directory entries. The kernel deletes files once all >> references are gone. > > Well, FS writers generally keep the link count and open count separate > entities, largely because they are. Then there's a separate "ref count" > for all the kernel threads ... I was using "references" generically, not to call out a particular data element. I was unaware there was an actual data element in the kernel called "ref count", or I might have made this explict. Why do you feel files are so unloved? :) -- Ben ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
Re: IPMI security article
On Tue, 2013-02-19 at 16:04 -0500, Michael ODonnell wrote: > > IPMI was involved with reestablishing communications with > your Dom-0 ? Interesting. Was that via Serial-Over-LAN? No. Sorry to confuse things. My Dom-0 has its own IP address. I had failed to map a firewall port to the Dom-0 ssh port. It had never been necessary for me to access Dom-0 remotely before. I was totally unaware of IPMI until I encountered that article grumbling about IPMI security. I did not even know that I had IPMI on my server - a fairly low-cost Supermicro box. -- Lloyd Kvam Venix Corp. 1 Court Street, Suite 378 Lebanon, NH 03766-1358 voice: 802-448-0836 fax:320-210-3409 ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
Streaming video from MIT classrooms for BLU meetings?
In the past we've had discussions about providing streaming video of BLU meetings, but none of us were sure how to go about setting it up. However, at last month's BLU meeting, someone pointed out that MIT's classrooms now have built-in cameras which should make the process feasible. I contacted MIT's Sloan School tech support about the classroom's built-in cameras, and they said we could use the self-service IP video conferencing function of the room to provide streaming video via an outside service, but they cannot provide any support for us, so we need to figure out the details on our own. Is anyone familiar with how to use their video conferencing, and what we would need to set up for the outside service? Ideally I'd like to install something on one of the BLU servers using an open-source engine that can both stream the live video and simultaneously capture it to a file that we could later edit and upload to YouTube. Here are the technical details their tech support folks provided: > I'm sorry, but we can’t accomodate your request for video streaming > and recording using the Sloan School’s in-house services. The reason > is partly our service model, and partly technology driven. On the > service side, the recording service is only available to the MITSloan > community for academic uses or for events by official MIT Sloan groups. > On the technical side, the camera and microphone outputs are only > routed into the Sloan School’s classroom recording and video > conferencing systems, so there is no way to direct the output to a > laptop, or even to the in-room computers, for capture in YouTube or > any other software client. > > You are welcome, however, to use the self-service IP video conferencing > function of the room. The rooms use Cisco C-series codecs, which operate > on the h.323 standard, and connect via TCP/IP. If you have access to a > service that you can call and stream to using h.323 you may be able to > provide a live stream to your group. This is a self-service function of the > room however, and we will not be able to provide you with additional > assistance. Simply select the video conferencing function and dial the > IP address or FQDN using the dialer pad. -- John Abreau / Executive Director, Boston Linux & Unix Email j...@blu.org / WWW http://www.abreau.net / PGP-Key-ID 0xD5C7B5D9 PGP-Key-Fingerprint 72 FB 39 4F 3C 3B D6 5B E0 C8 5A 6E F1 2C BE 99 ___ gnhlug-discuss mailing list gnhlug-discuss@mail.gnhlug.org http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
