20
votes
1answer
27k views

How to reduce number of sockets in TIME_WAIT?

Ubuntu Server 10.04.1 x86 I've got a machine with a FCGI HTTP service behind nginx, that serves a lot of small HTTP requests to a lot of different clients. (About 230 requests per second in the peak ...
22
votes
5answers
26k views

What is the difference between SAN, NAS and DAS?

What is the difference between SAN, NAS and DAS?
25
votes
13answers
3k views

Server Hosting from your House - $200 to $300 per month range

I'm a developer lacking some infrastructure knowledge. What is the fattest pipe I can get to my house in the $200 to $300 range? I'd like to host a few servers at my house. Then if my company gets ...
18
votes
5answers
2k views

Unix Server Partitioning & Filesystem Layout

There's a lot of contradictory information about Unix server partitioning out on the internet, so I need some advice on how to proceed. So far, on the servers I in our test environment I didn't ...
43
votes
8answers
40k views

Is a wildcard CNAME DNS record valid?

I know it's valid to have a DNS A record that's a wildcard (e.g. *.mysite.com). Is it possible/valid/advised to have a wildcard CNAME record?
23
votes
8answers
23k views

Will disabling hyperthreading improve performance on our SQL Server install

Related to: Current wisdom on SQL Server and Hyperthreading Recently we upgraded our Windows 2008 R2 database server from an X5470 to a X5560. The theory is both CPUs have very similar performance, ...
23
votes
7answers
28k views

Apache Default/Catch-All Virtual Host?

If I have 3 domains, domain1.com, domain2.com, and domain3.com, is it possible to set up a default virtual host to domains not listed? For example, if I would have: <VirtualHost 192.168.1.2 ...
13
votes
10answers
23k views

How do I know if I am running 32 or 64-bit Linux?

what would be a command to run in different distros?
42
votes
6answers
30k views

Is X.Y.Z.0 a valid IP address?

Are IP addresses with a 0 in the last octet valid? 10.6.43.0 In my case, I have the the following netmask 255.255.252.0 What about a 0 for the other octets?
12
votes
5answers
54k views

Huge amount of TIME_WAIT connections says netstat

Okay, this is creeping me out - I see about 1500-2500 of these: root@wherever:# netstat Proto Recv-Q Send-Q Local Address Foreign Address State tcp 0 0 ...
49
votes
10answers
6k views

Why drop caches in Linux?

In our servers we have a habit of dropping caches at midnight. sync; echo 3 > /proc/sys/vm/drop_caches When I run the code it seems to free up lots of RAM, but do I really need to do that. ...
10
votes
2answers
6k views

SSL site not using the correct IP in Apache and Ubuntu

I'm trying to set up an apache-ubuntu-php webserver. My webserver will host multiple SSL sites, each SSL site will have it's own IP address (unless there's a better way to do this). So I suppose the ...
14
votes
7answers
13k views

How to change “From:” field for emails from Cron?

I use remote SMTP via nullmailer and it requires set From field to the specific name, but cron set it as root@my.sweet.server.com. How could I change it to something like me@ya.ru?
4
votes
3answers
4k views

How to diagnose causes of oom-killer killing processes

I have a small virtual private server running CentOS and www/mail/db, which has recently had a couple of incidents where the web server and ssh became unresponsive. Looking at the logs, I saw that ...
2
votes
1answer
1k views

Setting up a Rails 2.3.x app on EC2 for easy scalability

I'm running a simple rails stack on a single dedicated machine. We're reaching our full capacity and have absolutely no setup for scaling, just one app on one machine. I did some research and came up ...
10
votes
9answers
24k views

NRPE unable to read output, but why?

I have this problem with NRPE, all the stuff I've found so far on the net seems to point me at things I've already tried. # /usr/local/nagios/plugins/check_nrpe -H nrpeclient gives NRPE v2.12 as ...
8
votes
2answers
4k views

Third-party SSD solutions in ProLiant Gen8 servers

I was wondering if anyone had any specific experience using Intel DC3700 SSDs (or similar) in the HP (DL380p) Gen8 servers? I'm upgrading a set of database servers that use direct-attached storage. ...
5
votes
6answers
24k views

Windows Event Log - email notification

Is there an easy way to send an email when a particular severity of event from a particular service hits the Windows server event log? This is on Windows Server 2003, if it makes a difference. n.b. ...
4
votes
5answers
2k views

Deep Format of a Harddrive on a Linux System

I've got an original Asus Eee PC Netbook that I'd like to sell. When I've sold old computers in the past, I've typically done a deep/secure/zeroing out style format. How can I do this on a Linux ...
3
votes
4answers
4k views

HP D2700 enclosure and SSDs. Will any SSD work?

I've got an HP D2700 enclosure that I'm looking to shove some 2.5" SSD drives in. Looking at the prices of HP's SSD drives vs something like an Intel 710 and even something less 'enterprisey', there's ...
3
votes
3answers
3k views

simple rsync in crontab without password

I would like to run the following: (Centos 5.4) rsync -avz /source_folder 192.168.1.1:/destination_folder right now I'm running it from CLI but eventually I would like to run it from crontab ...
6
votes
2answers
1k views

SQL Server memory constantly going up, from 1GB RAM used to 7GB in a week

I have a ~45GB database that increases rapidly (~1GB every week). So it's doing a lot of inserts; the web app doesn't have many users so reads are low right now. But I'm noticing that the RAM sql ...
3
votes
3answers
26k views

chmod -R 777 / on ubuntu - numerous problems

A client has accidentally given the entire filesystem full permissions on their ubuntu 10.04 box. chmod -R 777 httpdocs/cd / As you can see they attempted to cd to the root, and instead gave chmod ...
2
votes
1answer
633 views

Server refuses to use swap partition

We are running a server with 23 cores (cpuinfo shows 22 as the highest process number) and 66 Gig RAM. The development team here is running some apps, which hogs memory. I have observered that: 1. ...
4
votes
2answers
282 views

Accidential CHMOD 755

Alright, I accidentially chomdded everything to 755, which isn't as terrible as chowning everything to the local user. How insecure is this and how would I restore it easily, without reinstalling?
3
votes
3answers
3k views

How do I find out what is using up all the space on my / partition?

I am on a large instance on Amazon's EC2 servers. I run the df command and get: root@db:~# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda1 9.9G 9.1G 284M 98% / ...
2
votes
2answers
769 views

What do I need to parse incoming emails?

My intention is to parse incoming emails with PHP. What would be the simplest way to set this up? Would it suffice to rely on Postfix for this, or is there a better alternative? The purpose of the ...
1
vote
2answers
596 views

revert chmod 777 / -R

while executing a command i made a mistake and executed (ubuntu 10) sudo chmod 777 / -R # okay you may laugh now all my filesystem has 777 permitions , obviously i dont know which ...
0
votes
0answers
3k views

Aftermath of Hack

We recently faced a full scale attack on one of our servers running Open SUSE 11.0; the intruder deleted a lot of files necessary for day to day operation. Although the backups came in handy but for a ...
-1
votes
1answer
1k views

How do I open custom ports in my iptables firewall? [closed]

I need IPTables, like everyone else, but I don't use it enough to really keep my knowledge complete and fresh. The setup utility in CentOS is too basic. It doesn't seem to allow me to open up custom ...
140
votes
39answers
37k views

What useful things can one add to one's .bashrc? [closed]

Is there anything that you can't live without and will make my life SO much easier? Here are some that I use ('diskspace' & 'folders' are particularly handy). # some more ls aliases alias ll='ls ...
46
votes
9answers
60k views

What's the best way to move c:\users to d:\users under vista/W7 [closed]

I just installed Windows 7 RC1 and want to move c:\users to d:\users. What's the best way to do this? Due to the fact that Windows 7 creates a reserved partition that is mounted as C: in the ...
54
votes
5answers
14k views

Active Directory explained

If you had to explain Active Directory to someone how would you explain it?
46
votes
3answers
10k views

How does IPv6 subnetting work and how does it differ from IPv4 subnetting?

This is a Canonical Question about IPv6 Subnetting. Related: How does IPv4 Subnetting Work? I know a lot about IPv4 Subnetting, and as I prepare to (deploy|work on) an IPv6 ...
114
votes
12answers
9k views

Should servers be turned off at night?

There is a server that is used from 4:30 am in the morning until ~ 22:00. Should it be turned off? I think that it is a server and that it won't have a problem to stay on, but serious professors are ...
29
votes
6answers
4k views

Automatically Configure New Computers

My company is in the process of upgrading all of our users from old Windows XP computers to newer quad-core Win7 computers. This is a good thing - it's long overdue that we upgrade our workstations - ...
22
votes
7answers
20k views

how can I limit per user bandwidth?

To summarise: I have a dedicated server with a few friends running a torrent client with web gui. Each user is running a client under their username on the server so downloads go in their user dir, ...
32
votes
3answers
50k views

Can IIS be configure to forward request to another web server?

I have several web site set up on one IIS 6 server distinguished by Host Header. However, I wish to have one of the sites served by a Linux / Apache server on my network. Do I need to use a reverse ...
19
votes
9answers
5k views

Your troubleshooting rules, approach to troubleshooting?

Do you have any general rules that you fall back on when you troubleshoot a difficult network/hardware/software problem? Eg: "I isolate the source of the problem by testing a peripheral with a second ...
42
votes
10answers
6k views

RAID - software vs. hardware

I have always used hardware based raid because it (IMHO) it's on the right level (feel free to dispute this) and that OS failures are more common to me than hardware issues. Thus if the OS fails the ...
72
votes
7answers
27k views

Heartbleed: how to reliably and portably check the OpenSSL version?

I was looking at a reliable and portable way to check the OpenSSL version on GNU/Linux and other systems, so users can easily discover if they should upgrade their SSL because of the Heartbleed bug. ...
47
votes
15answers
43k views

Is FreeNAS reliable?

FreeNAS seems like a great product with a full checklist of features, even iSCSI. But how reliable is it? There are a few scary stories about lost data, for example here. Here is another example. If ...
29
votes
1answer
5k views

Why are my XFS filesystems suddenly consuming more space and full of sparse files?

I've run XFS filesystems as data/growth partitions for nearly 10 years across various Linux servers. I've noticed a strange phenomenon with recent CentOS/RHEL servers running version 6.2+. Stable ...
27
votes
6answers
33k views

Mac OS X multi-user thin client server (terminal server)?

Is there any solution out there to turn a Mac into a true multi-user thin client server? I'd like to set up a few cheap PCs with access to a couple accounts using something like VNC, but it isn't ...
14
votes
8answers
3k views

How many and which partitions should I create for a linux server?

Partitions are very important on Linux server because it give you a lot of flexibility, for example when upgrading to a bigger hard drive. But, how many partitions should I create when building a ...
23
votes
5answers
64k views

What is a system state backup for?

The windows backup utility comes with an option to backup the system-state. What is this for? Has it a real utility? Can I recover that windows on another machine?
9
votes
3answers
3k views

Secure LAMP server for production use

What is the procedure for securing a Linux, Apache, MySQL, PHP Server (or even Perl) for production use? Other than setting the MySQL password and the root password for Linux what other (maybe not so ...
7
votes
4answers
538 views

Steps to take to improve email deliverability

Successfully delivering email to my clients is a pretty high priority at my company. We are of course fully opt-in, paid clients, no possibility of spam, the whole thing. The information we email is ...
13
votes
4answers
4k views

Managing an application across multiple servers, or PXE vs cfEngine/Chef/Puppet

We have an application that is running on a few (5 or so and will grow) boxes. The hardware is identical in all the machines, and ideally the software would be as well. I have been managing them by ...
12
votes
9answers
2k views

Good low-cost SSL certificate providers

We need an SSL certificate to facilitate remote access and administration by a small number of employees. I don't want to have to train a bunch of non-technical users to install a self-published cert ...

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