Firefox managed to write 1.1GB to disk with the vast majority of data going into cookie* files.Then I went to Tools->File Summary to get overall stats.Left the three FireFox windows sitting idle for 45 minutes while I was using Chrome instead. I went back to File->Capture Events and re-enabled it.Cleared all events that were currently showing up. I went to File->Capture Events and disabled it.I launched Process Monitor and configured it to track recovery.js and cookie* files:.I opened a 3rd window and created a bunch of tabs showing front pages for various news sites.Simply searched for “samsung 850 pro review” and “samsung galaxy s7 review” and then went down the list of results opening them in new tabs. Next, I opened a bunch of random reviews for Samsung 850 pro and Samsung Galaxy S7 in two separate windows.I started the browser again and on this final restart the recovery.js file was only 5KB in size, down from around 900KB before.I opened a single window with just Google running in it, left it sitting for a couple of minutes, and then closed it.I reset to 15000 and then got rid of all my currently open FF windows.In case someone wants to replicate, here’s what I did this morning: Researching the issue a bit more over the next day, I discovered that things are worse than I originally thought and “recovery.js” isn’t the only file involved. Researching revealed that this is Firefox’s session backup file that is used to restore your browser sessions in case of a browser or an OS crash. That is extremely useful functionality. I was aware of the fact that Firefox had this feature, but I had no idea that session information was so heavy! To find out what’s going on, I fired up Resource Monitor and looked at disk utilization.Īt the very top of the list was Firefox, writing tirelessly at anywhere between 300K and 2MB per second to a file called “recovery.js”. firefox-with-32gb-written-in-a-single-day Even if the workstation was left idle with nothing running on it but a few browser windows, it would invariably write at least 10GB per day to the SSD. I monitored these stats over the next couple of weeks and this behavior stayed consistent. Since I didn’t recall downloading any huge files over the previous day or visiting any new sites that could’ve resulted in bringing down a lot of new content to the cache, this puzzled me. In my case, SSDLife notified me that 12GB was written to the SSD in one day. For those of you unfamiliar with this tool, it simply reports estimated lifetime for the attached SSD and it also shows the amount of data read and written. Purely by chance, I fired up a free copy of SSDLife on two consecutive days where I haven’t really used my workstation for anything other than email and browsing. Observing the Issue: Heavy SSD Writes from Firefox This issue is being discussed in a STH forum thread where you can follow the discussion. This can have an unintended effect for those SSDs as session store data can write data constantly to NAND.

Today’s modern multi-core processor systems and higher quantities of RAM allow users to open multiple Firefox tabs and windows simultaneously. If you are a user of Firefox we have a must-change setting.

Firefox sessionrestore