rytis's questions

What would be the best approach for CouchDB replication in the following setup:

A1 and A2 are two CouchDB servers in one DC. They both pull data from each other, although only one is actively used, the other is just a stand by in case of a failure of the first one.

B1 and B2 are similarly set up in terms of replication and are located in a different DC.

What's the best way of achieving A <-> B replication?

I see two options here:

Option 1:

• A1 pulls from B1 and B2
• A2 pulls from B1 and B2
• B1 pulls from A1 and A2

• B2 pulls from A1 and A2

• A1 pulls from A2

• A2 pulls from A1
• B1 pulls from B2
• B2 pulls from B1

Option 2:

• A1 pulls from B1
• A2 pulls from B2
• B1 pulls from A1

• B2 pulls from A2

• A1 pulls from A2

• A2 pulls from A1
• B1 pulls from B2
• B2 pulls from B1

IMHO Option 2 is sufficient and covers all bases for the HA setup, ie one way or the other no singe failure would prevent data from being replicated to all 4 DB instances.

There's not much data in there, we're talking about 50-100MB of data max.

Comments welcome. Thanks!

I have a site with only 3 URLs that need to be accessed via HTTPS. So I have 2 VirtualHost sections, one for HTTP (port 80) and the other for HTTPS (port 443).

Redirecting from HTTP to HTTPS is easy, I basically have this in the HTTP section:

RewriteEngine on
RewriteRule ^/wp-admin/(.*)$ https://%{SERVER_NAME}/wp-admin/$1 [R=permanent,L]
RewriteRule ^/wp-login.php$ https://%{SERVER_NAME}/wp-login.php [R=permanent,L]
RewriteRule ^/wp-register.php$ https://%{SERVER_NAME}/wp-register.php [R=permanent,L]

So whenever user wants to log in or register he will be redirected to a secure site. However, once the user has logged on, I don't want him to stay on HTTPS. Obviously, I could change WP code to redirect back to HTTP, but unfortunately that's not an option.

So the question is, how do I define RewriteRules in the HTTPS so that all requests will be redirected to HTTP only if they are not the following URLs:

/wp-admin/(.*)$
/wp-login.php$
/wp-register.php$

I hope that makes sense...

I'm trying to install the Base group on a mounted volume.

Here's the custom yum.conf that I'm using:

[main]
cachedir=/var/cache/yum/
debuglevel=2
logfile=/var/log/yum.log
exclude=*-debuginfo
obsoletes=1
gpgcheck=0
reposdir=/dev/null


[base]
name=Fedora 13 - i386
baseurl=file:///media/Fedora\ 13\ i386\ DVD/
enabled=1

[updates]
name=Fedora 13 - i386 - Updates
baseurl=http://mirror.sov.uk.goscomb.net/fedora/linux/updates/13/i386/
enabled=1

When I run

# yum -c yum.conf --installroot=mnt groupinstall Base

I would expect yum to install everything under mnt

But it keeps on saying:

[...]
Package irda-utils-0.9.18-10.fc12.i686 already installed and latest version
Package time-1.7-37.fc12.i686 already installed and latest version
Package man-pages-3.23-6.fc13.noarch already installed and latest version
Package talk-0.17-33.2.4.i686 already installed and latest version
Package pam_passwdqc-1.0.5-6.fc13.i686 already installed and latest version
[...]

I tried

rpm --base=mnt --initdb

and then use rpm to install fedora-release (which worked and installed the package under /mnt)

But yum keeps on saying that all packages are installed.

Any ideas?...

This is bit of a theological question, but nonetheless...

So, a server has a hostname, let's say the fqdn is hostname.example.com (to be really precise about what I mean, this is the name that is set in /etc/sysconfig/network).

The very same server has multiple interfaces on different subnets. Let's say the IPs are 10.0.0.1 and 10.0.1.1.

Now the question is, is it theoretically (mind you, this is important, I know that practically it works, but I'm interested in purely academic answer) allowed to have the following setup:

interface1.example.com. IN A 10.0.0.1
interface2.example.com. IN A 10.0.1.1
hostname.example.com. IN CNAME interface1.example.com.

OR should it rather be:

hostname.example.com. IN A 10.0.0.1
interface2.example.com. IN A 10.0.1.1
interface1.example.com. IN CNAME hostname.example.com.

I guess it's obvious which one is making more sense from the management/administration POV, but is it technically correct?

The argument against the first setup is that a reverse lookup to 10.0.0.1 returns interface1.example.com and not what one might expect (ie the hostname: hostname.example.com), so the forward request and then sub sequential reverse lookups would return different results.

Now, as I said, I want a theoretical answer. Links to RFC sections etc, that explicitly allows or disallows use of CNAME name as a hostname. If there's none, that's fine too, I just need to confirm. I failed to find any explicit statements so far, bar this book, where this situation is given as an example and implies that it can be done as one of the ways to avoid MX records pointing to a CNAME.

UPDATE: Multiple interfaces are not for redundancy (they're bonds anyway) but to achieve a logical separation in traffic. For example all DB traffic is on subnet A, services traffic is on subnet B and public access is on subnet C.

UPDATE2: Looks like this is not regulated by RFCs/other rules and is a matter of preference. Therefore I'll mark @Vatine answer as the workable answer for now which implies that there are no regulations. Also many thanks to @Alnitak for suggestions and discussion!