Re: [CentOS] Not firewall, but what?
On 05/08/2010 11:28 PM, JohnS wrote: > If I were you I would start from scratch and go step by step and set > it up. > > John I'm in agreement with John here. Your set up looks complex and may be starting from scratch is the way to go. Looking back though the thread, your set up might also be unnecessarily complex. I'm not entirely sure why you have two xen bridges and two vlans on the xen host, but that may just be the way the xen setup scripts work, and, well, I've never used xen. (I use libvirt with KVM, plus virtio to give me decent performance, and I hardwire my bridges in my network-scripts so I can ensure they are up and running before anything tries to use them). I think the problem is either ARP or routing (or both) or an overly complex setup (or all three) ;-) Lets start with ARP. ARP is pretty reliable and usually 'just works' on most networks -- so much so that it rarely causes any problems and is easy to forget about. The one situation that is guaranteed to cause a problem is having two host with the same IP address on the same network. (I had a situation once where a technician reset a problematic UPS to its defaults -- giving it the same IP address as one of our core routers and causing us no end of problems till we figured it out). This situation is tricky to troubleshoot because some parts of the network may be quite stable depending on the layout of bridges. (I had another situation once where a wireless router was reset to defaults and took on the IP address of the main gateway -- one bunch of Linux machines behind one switch was stable whereas another bunch of Windows machines behind a different switch was unstable with arp entries flip-flopping every 10 minutes or so). I mention this case in detail because: 1) you're migrating from an existing setup and there is a small chance that the old host is still on the network and has the problematic IP address, or there is some static APR entry lying around somewhere, and double checking may save you some sanity; and 2) you're using virtualization and bridges which means ARP has to flow and (in complex set ups) is why turning on STP can help. For completeness (and the archives) detecting the 'multiple hosts with the same IP' case is pretty easy: just install arpwatch on a host that receives traffic from all hosts on the network (router, dns server, dhcp server). You get a nice little email every time it thinks an IP address is flip-flopping. You also get a nice little email every time someone plugs a new device into your network (say, the cleaner's laptop at 2am). If you don't have arpwatch, then you could try: while true; do arp -n >> arp.log; sleep 5; done for 10-15 minutes (longer on a quiet network) and then do sort -u arp.log If the same IP address pops up twice, you have a problem. Tracking down the culprit is a little harder, but you can use the fact that the leading portion of the HW address is usually the same for the same NIC manufacturer. If the offending HW address is similar to those used by, say, known SUN machines, then that rules out any, say, Dell desktops. The arp.log file you just created can be handy for making these comparisons. The above problem is rare. I've only experienced on 'real' hardware 3 times in the passed 10 years, but I've seen it a lot more since I started playing with virtualization. A more common issue is ARP requests not flowing around your network properly. Bridges allow you to join networks together by passing along ARP queries. If you have multiple bridges, you can get loops, and this can prevent the ARP query reaching the right bridge, so you need STP to ensure bridges cooperate appropriately. (You can get by without STP, but only if you are 100% sure there are no loops). Firewalls can stop ARP flowing as well. On Linux this is arptables and ebtables. I note that your xen startup scripts turn this off, so you should be good, provided turning them off doesn't block ARP forwarding. Not sure about that. (I notice they are on on my systems, but I like to restrict traffic on the bridge, with the iptables/arptable/ebtables configuration managed by shorewall). I troubleshoot the above ARP issue the same way as for routing and firewalls, so lets move onto that. For newbies and the archives, I'll detail my approach. Firstly, you want to map out whether or not traffic can pass between various IP addresses. These flows may or may not be bi-directional (A to B, is not necessarily the same as B to A) depending on stateful firewalls and convoluted routing. If there are more than 2 addresses involved, things can get complicated and its easy miss important clues, so its good to be organised. I usually grab a scrap piece of paper and draw up a NxN matrix of the problematic IP addresses so I can note which flows pass and which flows fail. I also add a few good IP addresses (your desktop, routers, dhcp server, dns server, xen host, other guests, home desktop, are good cand
Re: [CentOS] which gcc package?
Robert Heller wrote: > You just need to do 'yum install gcc gcc-c++ binutils glibc-devel'. That seems to have done the trick. I do get compile errors, but I think there's a problem with the code. Thank you. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
On 9 May 2010 12:57, Michael Klinosky wrote: > Robert Heller wrote: >> You just need to do 'yum install gcc gcc-c++ binutils glibc-devel'. > That seems to have done the trick. I do get compile errors, but I think > there's a problem with the code. Depending on the requirements of the source code you are trying to compile you might have to fetch some development packages for various libraries, for example if it uses ncurses, you will want ncurses-devel package. -- Hakan (m1fcj) - http://www.hititgunesi.org ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] disable autofs timeout
aurfal...@gmail.com wrote: > Hi, > > Does setting the autofs timeout=0 create a permanent mount? > > What I'm trying to do is get the best of both world; > > 1) Have a persistent mount so that users can use autocompletion. > 2) utilize the benefits of autofs so that when an NFS resource becomes > unavailable, the system doesn't hang. > > I've tried a timeout of 0 but it doesn't seem to work. I can't see that making an autofs mount permanent will help ... If the NFS server goes away and it is mounted on your client (via the automounter or statically), the client will still hang on accessing the mount point. If you want to 'see' all the automount mount points, then start the automounter with BROWSE_MODE="yes" (in /etc/sysconfig/autofs) James Pearson ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] disable autofs timeout
On May 9, 2010, at 9:49 AM, James Pearson wrote: > aurfal...@gmail.com wrote: >> Hi, >> >> Does setting the autofs timeout=0 create a permanent mount? >> >> What I'm trying to do is get the best of both world; >> >> 1) Have a persistent mount so that users can use autocompletion. >> 2) utilize the benefits of autofs so that when an NFS resource >> becomes >> unavailable, the system doesn't hang. >> >> I've tried a timeout of 0 but it doesn't seem to work. > > I can't see that making an autofs mount permanent will help ... > > If the NFS server goes away and it is mounted on your client (via the > automounter or statically), the client will still hang on accessing > the > mount point. I see, I was hoping to test and find out exactly what would happen. Brian Mathis had a great suggestion so I went with it (crontab ls). ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Broken upgrade to memcached
Am 08.05.10 17:25, schrieb Axel Thimm: > In a nutshell: ATrpms does try hard to keep CentOS users happy. :) And thank you for that >:) Cheers, Ralph ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] measuring kernel speed
This is an interesting topic. So, how does one compare the kernel "speed" from RT and Stock kernel? Is there a benchmark I can use? For example (I know this is wrong): can I look at /proc/cpuinfo and look at the bogmips and compare and contrast? On Sat, May 8, 2010 at 7:38 PM, JohnS wrote: > > On Sat, 2010-05-08 at 16:17 -0400, Ross Walker wrote: >> On May 8, 2010, at 8:35 AM, Mag Gam wrote: >> >> > At our Physics research labs we do a lot with low latency networks. We >> > have been using Centos for over 3 years now and its been great! We >> > would like to tune and optimize our setup by removing unneeded >> > packages -- kernel modules to be specific. I was wondering, how does >> > one measure the speed of the kernel. Is that even possible? >> >> Use oprofile. >> >> -Ross > --- > Ross, never mind I just yummed it onto a machine there faq is inheritly > wrong. > > John > > ___ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos > ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Hakan Koseoglu wrote: > Depending on the requirements of the source code you are trying to > compile you might have to fetch some development packages for various > libraries, for example if it uses ncurses, you will want ncurses-devel > package. This problem seems (to my semi-newby brain) to be related to X -- [r...@sr1220 plugger-5.1.3]# make gcc -c -O2 -Ipluginsdk/include -INONE -DXP_UNIX -DVERSION=\"5.1.3\" -fPIC -o plugger.o plugger.c In file included from plugger.c:43: pluginsdk/include/npapi.h:129:22: error: X11/Xlib.h: No such file or directory In file included from plugger.c:43: pluginsdk/include/npapi.h:148: error: expected specifier-qualifier-list before ‘Display’ plugger.c:48:19: error: X11/X.h: No such file or directory plugger.c:49:21: error: X11/Xos.h: No such file or directory plugger.c:50:27: error: X11/Intrinsic.h: No such file or directory plugger.c:51:23: error: X11/Xatom.h: No such file or directory plugger.c:76: error: expected specifier-qualifier-list before ‘Display’ plugger.c: In function ‘my_fork’: plugger.c:231: error: ‘struct data’ has no member named ‘flags’ plugger.c:232: error: ‘struct data’ has no member named ‘display’ ... and a bunch more errors (which are probably due to these). I emailed the coder yesterday - still waiting for a reply. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Am 09.05.2010 17:48, schrieb Michael Klinosky: > Hakan Koseoglu wrote: >> Depending on the requirements of the source code you are trying to >> compile you might have to fetch some development packages for various >> libraries, for example if it uses ncurses, you will want ncurses-devel >> package. > > This problem seems (to my semi-newby brain) to be related to X -- > > [r...@sr1220 plugger-5.1.3]# make > gcc -c -O2 -Ipluginsdk/include -INONE -DXP_UNIX -DVERSION=\"5.1.3\" > -fPIC -o plugger.o plugger.c > In file included from plugger.c:43: > pluginsdk/include/npapi.h:129:22: error: X11/Xlib.h: No such file or > directory > In file included from plugger.c:43: > pluginsdk/include/npapi.h:148: error: expected specifier-qualifier-list > before ‘Display’ > plugger.c:48:19: error: X11/X.h: No such file or directory > plugger.c:49:21: error: X11/Xos.h: No such file or directory > plugger.c:50:27: error: X11/Intrinsic.h: No such file or directory > plugger.c:51:23: error: X11/Xatom.h: No such file or directory > plugger.c:76: error: expected specifier-qualifier-list before ‘Display’ > plugger.c: In function ‘my_fork’: > plugger.c:231: error: ‘struct data’ has no member named ‘flags’ > plugger.c:232: error: ‘struct data’ has no member named ‘display’ > ... and a bunch more errors (which are probably due to these). > > I emailed the coder yesterday - still waiting for a reply. You need to install an additional -devel packages. yum provides */Xlib.h libX11-devel-1.0.3-11.el5.x86_64 : X.Org X11 libX11 Entwicklungspaket Repo: base Matched from: Filename: /usr/include/X11/Xlib.h Same result for all the other missinge includes. Alexander ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Alexander Dalloz wrote: > You need to install an additional -devel packages. Given a list of 10 choices, that would've been at the bottom. I _never_ would have guessed! > yum provides */Xlib.h Thank you for today's linux lesson. I'm just delving into compiling programs. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Michael, On 9 May 2010 16:48, Michael Klinosky wrote: > Hakan Koseoglu wrote: >> Depending on the requirements of the source code you are trying to >> compile you might have to fetch some development packages for various >> libraries, for example if it uses ncurses, you will want ncurses-devel >> package. > This problem seems (to my semi-newby brain) to be related to X -- > > [r...@sr1220 plugger-5.1.3]# make > gcc -c -O2 -Ipluginsdk/include -INONE -DXP_UNIX -DVERSION=\"5.1.3\" > -fPIC -o plugger.o plugger.c > In file included from plugger.c:43: > pluginsdk/include/npapi.h:129:22: error: X11/Xlib.h: No such file or > directory You need to get familiar with how C libraries work. You are trying to compile a package which calls the Xlib library. The definitions for the library (i.e., what methods and functions are available to programmer) is stored in a file called header file which ends with the extension h. In most distributions, these are stored separately to the libraries (i.e., runtime only dependencies). If you do a search for your missing header file with the command yum provides *X11/Xlib.h you will see that this is provided with the libX11-devel package. Then you can install this package with the command yum install libX11-devel and so on for all of your missing dependencies. > I emailed the coder yesterday - still waiting for a reply. This is nothing to do with the coder. I think you will wait for a while for the reply. :) -- Hakan (m1fcj) - http://www.hititgunesi.org ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Michael Klinosky wrote: > Alexander Dalloz wrote: >> You need to install an additional -devel packages. > > Given a list of 10 choices, that would've been at the bottom. I _never_ > would have guessed! > >> yum provides */Xlib.h > > Thank you for today's linux lesson. I'm just delving into compiling > programs. This isn't really 'linux' specific. It relates to the way distributions are packaged. If you don't compile things locally, you don't need all the .h header files so they are split into separate package-devel packages. You can get a bunch of them at once if you pick the development-related groups during an install or you can do a 'yum grouplist', then 'yum groupinstall ...' for the ones you are likely to need. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
At Sun, 09 May 2010 11:48:53 -0400 CentOS mailing list wrote: > > Hakan Koseoglu wrote: > > Depending on the requirements of the source code you are trying to > > compile you might have to fetch some development packages for various > > libraries, for example if it uses ncurses, you will want ncurses-devel > > package. > > This problem seems (to my semi-newby brain) to be related to X -- > > [r...@sr1220 plugger-5.1.3]# make > gcc -c -O2 -Ipluginsdk/include -INONE -DXP_UNIX -DVERSION=\"5.1.3\" > -fPIC -o plugger.o plugger.c > In file included from plugger.c:43: > pluginsdk/include/npapi.h:129:22: error: X11/Xlib.h: No such file or > directory > In file included from plugger.c:43: > pluginsdk/include/npapi.h:148: error: expected specifier-qualifier-list > before Ã`Display´ > plugger.c:48:19: error: X11/X.h: No such file or directory > plugger.c:49:21: error: X11/Xos.h: No such file or directory > plugger.c:50:27: error: X11/Intrinsic.h: No such file or directory > plugger.c:51:23: error: X11/Xatom.h: No such file or directory > plugger.c:76: error: expected specifier-qualifier-list before Ã`Display´ > plugger.c: In function Ã`my_fork´: > plugger.c:231: error: Ã`struct data´ has no member named Ã`flags´ > plugger.c:232: error: Ã`struct data´ has no member named Ã`display´ > ... and a bunch more errors (which are probably due to these). > > I emailed the coder yesterday - still waiting for a reply. This should get you all of the X11 header files and link libraries (probably more than you need): yum install libX11-devel xorg-x11-proto-devel libXau-devel libXdmcp-devel > > ___ > CentOS mailing list > CentOS@centos.org > http://lists.centos.org/mailman/listinfo/centos > > > -- Robert Heller -- Get the Deepwoods Software FireFox Toolbar! Deepwoods Software-- Linux Installation and Administration http://www.deepsoft.com/ -- Web Hosting, with CGI and Database hel...@deepsoft.com -- Contract Programming: C/C++, Tcl/Tk ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] which gcc package?
Les Mikesell wrote: > You can get a > bunch of them at once if you pick the development-related groups during an > install or you can do a 'yum grouplist', then 'yum groupinstall ...' for the > ones you are likely to need. Benjamin suggested that also. But, I don't really want tons of extra stuff on my machine. And, I think that it actually worked out better; I now know the underlying problem, and how to solve it. If I would've used 'groupinstall', it would have worked, but I wouldn't have known about the missing library. So, the next time I compile a program, I'll think back to this and realize that, most likely, I'm missing a library or somesuch. I installed libX11-devel, then tried again to make - failed, but for a different library. I found it, installed it, 'make', and it succeeded. Basically, I want to know how these things work. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] measuring kernel speed
On Sat, May 8, 2010 at 7:38 PM, JohnS wrote: > > On Sat, 2010-05-08 at 16:17 -0400, Ross Walker wrote: >> On May 8, 2010, at 8:35 AM, Mag Gam wrote: >> >> > At our Physics research labs we do a lot with low latency networks. We >> > have been using Centos for over 3 years now and its been great! We >> > would like to tune and optimize our setup by removing unneeded >> > packages -- kernel modules to be specific. I was wondering, how does >> > one measure the speed of the kernel. Is that even possible? >> >> Use oprofile. >> >> -Ross > --- > Ross, never mind I just yummed it onto a machine there faq is inheritly > wrong. The FAQ is only correct in respect to the project's view. Redhat has a custom oprofile that works with their custom kernels, so stock oprofile from the project's site IS incompatible, but that's OK cause RH provides one that works with their distro. -Ross ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] measuring kernel speed
On Sun, May 9, 2010 at 11:38 AM, Mag Gam wrote: > > On Sat, May 8, 2010 at 7:38 PM, JohnS wrote: >> >> On Sat, 2010-05-08 at 16:17 -0400, Ross Walker wrote: >>> On May 8, 2010, at 8:35 AM, Mag Gam wrote: >>> >>> > At our Physics research labs we do a lot with low latency networks. We >>> > have been using Centos for over 3 years now and its been great! We >>> > would like to tune and optimize our setup by removing unneeded >>> > packages -- kernel modules to be specific. I was wondering, how does >>> > one measure the speed of the kernel. Is that even possible? >>> >>> Use oprofile. >>> >>> -Ross >> --- >> Ross, never mind I just yummed it onto a machine there faq is inheritly >> wrong. >> >> John >> > This is an interesting topic. > > So, how does one compare the kernel "speed" from RT and Stock kernel? > > Is there a benchmark I can use? For example (I know this is wrong): > can I look at /proc/cpuinfo and look at the bogmips and compare and > contrast? I think there are numerous ways, but of the top of my head, oprofile the application on the stock kernel, then oprofile the application on the RT kernel and compare the results. -Ross ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] Formatting file system too slow on CentOS
Dear All, I've a new server HP DL 180 G6 with quad core processor, ram 4 GB, hdd (WDC) 1x750GB Sata. I was confused when installing CentOS 5 64bit on that server, I take about two hours to format the ext3 file system. is this normal? Because when I compare with other sata hard drive in another computer file system format is not too long like that. And when I copy the file on the local hard drive for longer time when compared with the copy of the file on another server. How to debug on this issue? -- Best regards, David http://blog.pnyet.web.id ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Formatting file system too slow on CentOS
2010/5/10 David Suhendrik : > Dear All, > I've a new server HP DL 180 G6 with quad core processor, ram 4 GB, hdd > (WDC) 1x750GB Sata. > I was confused when installing CentOS 5 64bit on that server, I take > about two hours to format the ext3 file system. is this normal? well, that size of ext3 usually takes lot of time. use xfs, if you want fast format.. -- Eero ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
