From MacBook to MacBook Air

Give me hints, please! :bulb:
I just switched from an old MacBook with 500 GB HD to a MacBook Air with 124 GB SSD. All is well, but I wonder which is the better strategy for the new organization of my huge DataBases.
I have many thousands of PDF linked to a more than 20.000 entry Bookends database. I have had also a huge DataBase of DEVONThink Office Pro 1 with all my documents and with a smart folder which automatically indexed the content of the folder containing the attachment of my Bookends library. All was well. Then, after the number of my BE database and PDFs increased, I was obliged to remove the smart folder (too slow for my old processor), and then, with DEVONThink Office Pro 2, I divided my huge database into some different “specialized” databases.
Now for the first time for me the HD capacity is crucial. Is it possible to put on the SSD the huge database, the result of a reunification of the “specialized” databases, and link with some folders on an external drive containing all the PDFs and so on? Which is the most attentive mode to store in a database a large amount of PDF files?
Thank you very much
TG :question:

There are two issues to consider:

  1. It’s very important to keep a reasonable percentage (at least 15% - and more is better) of your SSD capacity available, to leave room for temporary files used by the operating system (e.g., Virtual Memory swap files) and applications. Running out of free drive space is an invitation to disaster, as the operating system may overwrite data files.

From that perspective, you can save SSD drive space by placing your large collection of PDFs on an external drive, and Index-capturing them into your DEVONthink databases. The downside, of course, is that an external USB drive hooked to the MB Air will have much slower access speeds than does the SSD - and of course, the externally stored files won’t be available to view/edit/print unless the external drive is mounted.

  1. I don’t know the total word count of your databases. My own rule of thumb, given the maximum 4 GB RAM available in a MB Air, is to keep the total word count of either a single database or of a set of open databases less than 40 million total words in order to leave some free RAM headroom available. Otherwise, Apple’s Virtual Memory will start swapping data back and forth between RAM and disk, resulting in growing Virtual Memory swap files and a performance slowdown.

Although I’ve got an iMac with lots more RAM and drive space, I do most of my work on my Air, with 251 GB SSD, i7 CPU and 4 GB RAM. I can’t fit all my databases on the Air. I ‘cheat’ by hooking up via Thunderbolt to a Pegasus RAID drive with 3 TB formatted capacity, and of course very fast access speeds. That’s fine, so long as I don’t need to be on the move. The Pegasus unit weighs many times more than the Air, and is definitely not portable. :slight_smile:

When I launch DEVONthink Pro Office with my normal set of open databases, I’ll see about 1500 MB to 2000 MB free RAM space remains available, so that database work moves along at full speed. But over time, especially if other apps such as a Web browser are also open, the amount of free RAM will gradually decrease. To keep the Air running fast, I monitor free RAM. When it drops so that pageouts start happening, I will use C0cktail’s Memory Purge feature to reduce the amount of inactive RAM and increase free RAM headroom.

Thank you for your kind answer, Bill. For me the speed is less crucial than the DB dimension.