Why is ReadyBoost only using 4GB when I have dedicated 32GB?

Readyboost should have no problem allowing 32GB of space on Windows 7, so long as you have formatted the drive using NTFS or exFAT. If you have formatted it as FAT32, though, you'll be limited to 4 GB.

Note that you are unlikely to see significant performance gains on modern hardware, mind you. You'd be better off going for an SSD. Still, Readyboost may provide a small benefit to you, particularly if your existing mechanical drive is old and slow.

ChrisInEdmonton

Posted 2014-07-28T18:17:59.543

Reputation: 8 110

The ReadyBoost cache is stored in a .sfcache file on the target drive, and "[t]he largest possible file for a FAT32 drive is 4 GB minus 2 bytes." (Source) Also, quoting Wikipedia: "In Vista or with FAT32 formatting of the drive, the maximum is 4 GB. In Windows 7 with NTFS or exFAT formatting, the maximum cache size is 32 GB per device. Windows Vista allows only one device to be used, while Windows 7 allows multiple caches, one per device, up to a total of 256 GB." (Source)

– and31415 – 2014-07-28T19:30:17.777

My drive is formatted as FAT32. Can I reformat it to exFAT or NTFS to leverage the full capacity? Is this recommended? – user1477388 – 2014-07-29T13:07:44.277

Yes. So long as you are okay with losing everything on that drive (likely fine, as you plan on using the whole thing for Readyboost), this is indeed the recommended course of action. – ChrisInEdmonton – 2014-07-29T14:06:01.687

You are allowing Windows to determine how much to allocate to ReadyBoost. You can't allocate more then Windows wants, even if you do it manually, there will be a physical limit based on your actual system's need. Your current configuration clearly indicates you have only allocated 4GB to ReadyBoost. – Ramhound – 2014-07-28T18:25:28.050

Why is ReadyBoost only using 4GB when I have dedicated 32GB?

Answers