As part of my reinstall effort, I'm trying to keep everything nice and tidy. To that end, I'm putting virtually every resource from every mod into a BSA archive - that way the mod is easy to remove if necessary!

I know that this will work for mods that come with ESP files that need to be activated in my load order. But, what about graphics/sound/etc. replacers that don't use ESP files? Will, for example, the game access and use files within my "Bomret's Enhanced Normal Textures.bsa"? Do I need to add them to Oblivion.ini? Or, should I just leave those files loose in the data directory?

Additionally: In cases of conflicts - where more than one version of the same file exists in different BSAs--which file will "win"? Is it the BSA whose ESP loads last, the BSA with the latest date, or the file within the BSA with the latest date?

(If there's some place I can read up more on these, let me know.)

1. Installing with BAIN will make it easy to remove a mod, regardless if it's resources are in a bsa or not.

2. You can add the bsa to the Oblivion.ini manually, or create a dummy .esp file that will load it. Personally, I keep just texture files loose.

3. This is where "install order" is key. Last load will win. Unless there are loose files and they will win.

A couple of concerns to keep in mind.

#1: BSA files count toward the file limit. The game has a hard limit of 400 files, be they ESP, ESM, or BSA files. Exceeding this will cause the game to CTD at random times with no real pattern.

#2: BSA files cannot contain overlapping content. At best, you'll get the game randomly choosing a file from a different BSA and this can happen within the same play session. At worst, you'll crash the game doing this. So for that reason replacers cannot be in a BSA unless you overwrite the originals.

Thanks for the input! Sounds like it's unwise to put everything in BSAs. I'll limit to those that have accompanying ESP files.

What I have done in the past is to take my texture and meshes replacers (without esp files) and overwrite the vanilla meshes and textures BSA files (had to create multiple ones because of size). Worked pretty well but then I did not expand on the game too much as it had all I wanted to play. No difference in performance that I noticed. Not sure why I bothered at all, other than I could With BAIN it is better to do loose files as I can easily remove files or change load order to have the file I want in game. a zip is easier to modify than a bsa.

The main reason for going with BSAs is because they can improve disk performance over loose files. Though that is probably only the case if your drive is properly defragged.

I took all the graphics replacers I use and incorporated them into the vanilla files. There otta be a guide to this. Maybe I'll write up a proper one, but for quickie purposes:

1. Unpack vanilla files. Do this one set at a time.
2. Gather up mods you want to include.
3. Copy the files from the mods you have and overwrite the unpacked vanilla files with them.
4. Grab PyFFI (make sure it's the very latest) and let it process the mesh folder. Go watch a movie or something - this will take hours.
5. Repackage the BSA files making sure none exceed 2.00GB. Split things up as needed. Uncompressed files perform slightly better.
6. Update your ini file with a proper list of the filenames you've got now.
7. Defrag your poor drive, it'll need it!

It seems to have worked wonders for me. Disk stutter is down, although not eliminated. There's no overlaps, so you see what is intended without the possible crashes or random picks.

Or, get an SSD. Disk stutter begone!

Solid State Drives are awesome! Unfortunately, also expensive.
Thanks Arthmoor for the advice. *goes back to installing*

Two follow-up BSA questions:


(1) Assuming that one avoids the 2GB file size limit that Arthmoor mentions, is there any advantage, or disadvantage, to collapsing BSAs together?
For example, Reclaiming Sancre Tor comes with separate Meshes, Textures, and Sounds BSAs. All three together are only about 750 MB. I'd like to collapse them together to subtract 2 files from that 400 file limit!

(2) I typically use the maximum available compression on BSAs, since I have limited disk space. I know this will increase stuttering just a bit. Are there any other disadvantage to max compression?

There shouldn't be an issue. It also would help keep all the files in the same place on the drive, improving performance.

Regarding compression, I'm unsure if there's anything else

The biggest advantage of collapsing BSAs together is for what you mentioned. To relieve the file count. Otherwise there's probably not a significant difference between leaving them as they are and combining them.

BFG I dont know if you have seen this but the 2gb BSA size limit (at least on vanilla Oblivion, DLC and Shivering Isles BSAs) can be helped a lot with http://www.tesnexus.com/downloads/file.php?id=41042

Extracting and re-packing BSAs is now available in one nice little utility (and its portable, installation is just a case of extracting it and running from wherever you put it (with enough space for extracted BSAs ofc)).

You can extract BSAs to the default 'out' folder (located in the folder you extract BSAOpt to), or you can paste the name of the BSA into the out path and it will re-pack the source BSA with the compression level you choose to the destination filename.

It retains filenames with leading spaces (for Pyffi fans, those meshes which dont work if the leading space of the filename is removed ... not a problem), and the optimization part of the name really is not BS, it has a new trick up its sleeve. I have repacked ALL of my Oblivion BSA's, with 0 (no) compression, and not one of them exceeds the 2gb limit

If you get any hash check errors with individual files from the source BSA then the utility you packed the source BSA with was at fault - There's a Skip Hash Check option which you can enable for a problem BSA which successfully copies the problem file across to your new BSA and then you have no further problems.
A note from the author ....

I found a couple of hash error files in BSAs which I had packed a while ago with OBMMex.

Ethatron has done a really good job of this, supports Skyrim too, read the comments while its no so big (no gamesas topic)
Windows XP not supported, only runs on Vista or 7.
The speed of this thing is stunning.

Edit: Tip from Lojack - If using Wrye Bash you can launch it as an App. The only part of BSA manipulation Wrye Bash could not do is now easily integrated.

WUH oh... so if I am using mesh replacers for clothing and armor to make them compatible with Robert's male body and Exnem's female body, I can't put them in a BSA file??? Is there no way to tell the game to just use whichever BSA is newer when there's a conflict?

You can, but you would have to recreate the original Oblivion Vanilla BSAs using your replaced content.

But...... but.... it really seems like there should be SOME way to just get Oblivion to use whichever is the newest! I mean, I just recently made a BSA that combined all the necessary files from the "Main Quest Delayed with Alive Kvatch" mod, and it seems to be working absolutely perfectly (which swaps out the LOD textures with new ones to make Kvatch look un-damaged)......

Ah, but you see, you are working under a fundamentally flawed assumption. You are assuming that this is a well designed engine.

Yea... I also found this thread which is pretty informative too on the same subject: http://www.thenexusforums.com/index.php?/topic/44672-bsa-behavior-question/
This is heart-breaking to me... I've been working on a huge project for the last 4 years that includes a few replacement files mixed in with tons of new content, and I wanted to pack it all up nice and neat into a bsa file, but now it seems like those plans are borked.

Yep, those plans are borked. I hate to bear bad news, but that's just the reality of it. The BSA system does not invalidate by date against other BSAs. Any files which are in another BSA need to be overridden as loose files. There's no other way around this.

Now to start sorting through all the BSAs I've completed so far with BSAOpt...if there exists a QUICK way to determine whether you have duplicate files spread across BSAs using BSAOpt, I haven't found it yet. But then again I've only been using the tool for a half day or so.

BSAopt doesn't have it. NIFopt has the possibility, but is has no front-end yet. It can built a database of the "Data"-folder with BSAs, but the lack of a front-end would require you to use SQL-queries to get that information out.