Multisite

I hope someone has run into something like this before... I'm using a group who's form duplicates nodes and automatically associates them to the new group. So you create a group, select a book in the system and it will grab the book, duplicate it and set the og node settings to the new group. Then it performs a node_save after removing the nid so it's a "new node" with the old content / hierarchy.

Sorry if this is a silly question - I've just started using Drupal last year and this is my first major upgrade.

I've got all my sites in one multi-site setup.

A couple of them are very simple, and basically good to go.

Can I upgrade just one of two of them at a time?

e.g. Could I create a new dir for drupal 7 and copy the sites over into it one at a time? (To eventually migrate all of them as the modules I need become available?)

FYI:

http://lx1.co.nz
http://nzmagic.co.nz

vs

http://amdramreview.co.nz
http://skeptember.com

I'm a noob here and I've run into a problem setting up multisites as subdirectories. I think I have it all done correctly except for this one error when Drupal is trying to access each site's 'files' folder. This is the way the error appears when I look at 'File system' page under 'Site configuration':

warning: fopen(sites/mulfordfam.dlinkddns.com.parisumc/files/.htaccess): failed to open stream: Permission denied in /usr/share/drupal6/includes/file.inc on line 129.

I've been trying to come up with a solid plan for moving forward with this file sharing portal for the company I work for.

I already have a skeleton in place that we use for sharing files with product dealers and collaborators, as well as receiving files from those with permission to upload to us. The site works rather well and I have permissions broken down into roles and specific users per file group.

While planning the migration of a large website to Drupal, a key architectural question emerged: one large "MegaSite" versus numerous "ManySites". The oragnization is large association with many divisions and groups with different levels of autonomy to manage their own sub-site. Why not go with many Drupal sites, one for each organizational unit, and use Aegir to manage the sites?

Would the simplicity and reduced number of contributed modules in the individual sites outweigh the additional burden of maintaining 15 – 20 individual sites with Aegir?

I'm on my first Multisite install after using Drupal for several years. I have set up my sites but I'm having trouble with one thing and I've scoured the discussions and tried several things I thought were the solution but no luck. I'm having trouble linking to image files, When I put a file in
/sites/example.com/files/artwerk/image.jpg
and link to it with example.com/artwerk/image.jpg
my site can't read it but if I put the same file in the root folder
/artwerk/image.jpg

I'm using a WAMP stack and the most recent Acquia Drupal 6.19 distribution.
In my Apache instance, I've setup multiple alias' for subdirectories that are part of my Drupal multi-site instance.

What I can't seem to figure out, is why I can't login to one of the added sites and enable modules specifically placed in that instance!

For instance, in "drupal/sites/all/modules", I have Rules and Workflow.
In "drupal/sites/webserver.jobs/modules", I have Job_Posting.

I am wondering whether multisite provides the solution I am looking for.

Here is my dilemma.

I have a website which is fairly established (over 3 years old) and was built by developers before I got involved myself. Recently I discovered drupal which looks like it provides all of the answers to my prayers with regards to this site, however as the bulk of the site is already coded I was wondering whether multisite would be a good solution prior to a full site migration.