Hypertown RedHat RHEL 5.2 Server Has Been Going Down Everyday
Jul 13, 2008
For the past two weeks, our Hypertown RedHat RHEL 5.2 server has been going down everyday because of a wierd Kernel Panic problem.
Attached you can see what was displayed on the console at the time of the panic. This is what SoftLayer tech. support team was able to obtain from the console.
I have a problem with time at one RHEL 4 server, it is a plain box, and from time to time the time (hours) seems to be auto modified, no one is touching the box and then from once it got modified to a few hours less than what we specified, to change time and date we always use:
Code: date --set "2007-10-24 13:35" hwclock --set --date="2007-10-24 13:35"
The only thing that I noted is that ntpd daemon was running, while in the rest of our plain box it is not running, maybe this is the reason the system is auto chaning the time?
has anyone else noticed an unusually high load occurring from 9 till 11 EEST time on their servers?
I've been getting high loads everyday this week at exactly these times.
I'm thinking that this is a crawler/bot that is causing the loads, i've already installed dos deflate and there hasn't been more than 100 connections from the same ip, so I'm ruling out any DOS attack ... besides, what kind of attack only takes place for 2 hours a day at exactly the same time?
I'm on a cpanel system and would like to know which logs to take a look at to determine the cause.
I have a problem with hoster. Purchased virtual hosting. All worked fine for more than a year. I did not make any changes in websites recently. Last several days one issue appears constantly: website starts downloading very slowly (30-60 sec for 20 kb page, or connection timeout). And each day their tech support don't realy want to help me. Only after 3-4 emails they fix the problem, but on the next day the problem arises again. I suppose they just ignore my problem. Possibly server is overloaded by other sites, or software was not tuned correctly, or something like that, and hoster does not want to solve the problem.
I have a dedicated server with many websites on it. The problem is that I got very high load every day in the midnight I checked all "my" crontab and they are all fine. I even stopped them but nothing changed. My backup time is not the midnight, it's about 6 AM.
I tried everything I could but everything still like before high load every night.
We have running exim mail service in cpanel web server. Exim consumed some CPU% memory and lots of threads are opening. More than 2000 mails in queue everyday. How can we optimize the exim mail service?
top - 06:33:12 up 23:12, 1 user, load average: 0.03, 0.08, 0.08
PID USER PR NI %CPU TIME+ %MEM VIRT RES SHR S COMMAND 4777 mailnull 15 0 1 0:00.02 0.2 9324 3936 2680 S exim 1809 mailnull 16 0 0 0:00.09 0.1 8192 1156 808 S exim 1815 mailnull 24 0 0 0:00.00 0.1 8428 1100 764 S exim 4779 mailnull 16 0 0 0:00.00 0.0 8200 684 336 S exim
on installing Mono but havnt found any. Tried their installer and it doesnt work at all.
Does anyone know of a tutorial out there that will help or can anyone provide me with step by step instructions for installing it to REDHAT Enterprise 4 i686
I am using WHM but read a lot of horror stories about installing it via WHM unless thats fixed. If it was fixed, how could i do this instead of a manual install?
Does anyone know how to sign up for the RedHat hosting program where you have to pay monthly for the licenses as opposed to yearly?
I called their support number but that guy asked me to sign up online for the Yearly license. But I know a lot of dedicated server companies have a monthly commitment.
Can anyone recommend their sales rep to me who knows exactly what I'm talking about? You can PM me their details if you want.
Going to order a new server fairly soon, and I'm facing the tough question if I should go with 64-bit or stay with the "classic" 32 bits. My operating system of choice is Red Hat Enterprise 4.
From the research I've done, RHEL 4 (64 bits) should come with dual libraries that would allow running 32 bit and 64 bit applications under the same 64 bit operating system. Sounds great, and if it comes with an overall performance boost I am all for it.
But I've also heard that that's only the theory - in reality, I could end up banging my head against the screen for uncounted hours because compatibility still isn't as good as it's supposed to be. I don't plan to run Plesk or Cpanel, but I still don't want to get into hot water with other applications I've been using on my current 32-bit server.
All in all it's intimidated me quite a bit, so I'd probably go with 32 bits this time around, just to be on the safe side. Then again, I'm still having an eye on the possible performance boost, so dunno. Does anyone have an idea what's the latest on this? 64 bit already safe for the non-experimental-minded, or bleeding edge and stay away from?
Is anyone here running GFS? The responsibility of managing a small cluster of them is about to fall into my lap, and the only documentation I can find is on Wikipedia, which is troubling. I've got the man pages, but I was hoping for more of a document outlining how it works.
Why would lock_dlm2 or gfs_scand take up close to 100% CPU with minimal traffic on the machine, for example? What do those do? How can I tune it to not do that?
I'm not so much looking for specific answers here about tuning, but am more curious about where I should be looking for documentation. I find it hard to believe that there is none?
I have a powerful 8 core 8gb ram web server with scsi raid drives running RedHat EL 4. This server handles 2,000 - 3,000 HTTP requests per second via Litespeed httpd without strain (over 60%+ CPU idle time during peak load, under 1% IO wait). As the traffic volume continues to increase I've encountered a strange problem, the symptoms of which are as follows:
- About 1/4 or 1/3 of new connections are not answered by the server - they time out.
- All connections that are answered have exactly 3 seconds added to the time it takes to establish connection with the server (can be seen as "Connecting to ..." phase in FireFox). HTTP response times were tested by Pingdom from multiple locations all over the world.
- The problem is either "on" or "off", it is not gradual.
- Server ping is unaffected during the problem - no delay and no packet drops.
- The problem does not happen during off-peak hours of the day.
If litespeed httpd settings are tweaked to keep as many connections as possible in keepalive state for as long as possible, the problem is avoided, while tens of thousands of connections are kept in keepalive state.
Possible causes that were tested and eliminated: PHP/MySQL load (problem applies to static files exactly the same), CPU / IO / RAM, network uplink, hardware firewall, DNS.
This makes me think that there is some kind of bottleneck of how many NEW connections per second the server can accept. By maxing out keepalive quantity and duration I'm reducing the number of new connections per second. This is a temporary fix that will only work up to a certain point.
After investigation, litespeed staff verified that my litespeed configuration was correct and after some testing said that nothing in litespeed was responsible for this limiting factor. Litespeed process uses relatively little CPU and can definitely handle more volume.
Following sysctl.conf values were increased substantially to see if that will make a difference: tcp_max_syn_backlog, tcp_max_tw_buckets, tcp_max_orphans, netdev_max_backlog, somaxconn, file-max. This didn't produce any results. Disabling syncookies didn't help either. dmesg doesn't have any notices of limits being hit or throttles being applied.
Litespeed staff suggests that likely some limit in linux kernel is being reached. The strange 3 second delay does seem like an "intelligent" DDOS protection strategy of some sort. Perhaps this is some kind of kernel level DDOS protection?
Anyone out there have experience with SuSE over RedHat? RHEL is obviously the generalized Enterprise version used across most commercial hosting companies, but I'm interested in hearing about some SuSE experiences people have had.
It looks like SoftLayer offers SuSE and a couple VPS hosting companies do the same. I'm wondering how many large-scale sites are run on this operating system.
Qmail on Redhat setup for mail relay? (I'm a newbie)
I'm trying to figure out how to enable mail relaying for a specific domain on a Redhat server running Qmail. Can anyone tell me where to look? I searched Google, but am now very confused.
I need to configure multiple Apache Web Servers on redhat server. I have copied and extracted Apache 2.2 into redhat server and extracted but not able to install because I don't understand setting prefix. Please let me explain about prefix configuration and how to set it. At the same time I would like to know is it possible to setup 4 Apache Web Servers on same machine if possible then how to. Can we set up different versions of Apache HTTP Servers?
With Red Hat Enterprise Linux 4 (RHEL 4), are updated packages made available, or are only security patches backported? Specifically I'm interested in vsftpd. Version 2.0.1 is included in the RHEL installation on a server I'm working on, but there is a bug fix in v2.0.4 that I'd like to get access to.
Is there an easy way for me to browse / search what packages are available for RHEL 4, preferably via website?
