Dropbox users are being urged not to rely on the cloud storage service as their sole means of backing up data, after a system glitch resulted in one man losing more than 8,000 photos.
Jan Čurn, CTO of CGI effects software maker VirtualRig Studio, claims a bug in Dropbox’s Selective Sync function caused 8,343 files to be permanently deleted from the cloud storage site.
In a comprehensive blog post, charting the event, he explains how he tried to use Selective Sync to free up space on his hard drive by moving a large number of photo-containing folders to Dropbox.
The Selective Sync feature is designed for this purpose, by allowing users to stipulate individual folders they may or may not want to sync to their computers.
However, shortly after Čurn authorised the sync event to go ahead on 29 April 2014, he claims the Dropbox client froze, prompting him to restart it.
“These directories are large and they might be too big of a bite for Dropbox, I thought, and unsycned them one by one instead,” he explained.
“Everything worked well, the directories disappeared from the local hard drive, but they were still available on Dropbox’s website. All good.”
Except, when Čurn came to need the files some time later, he discovered the directories stored on Dropbox were empty, as the result of a “delete event” that culled 8,343 files on 29 April 2014.
“I was devastated. All those memories and the effort with collecting and organising the photos... gone,” he wrote.
“Because there was never any problem with the service and also because it’s already the year 2014, I thought it might be about time that one can trust a cloud-based storage service and use them as a sole backup of [your] files. Boy, I was wrong,” he notes elsewhere on the blog.
He’s used the sequence of events to piece together a theory that Dropbox deletes the files people earmark for Selective Sync locally before its settings kick in.
“Consequently, if the client crashes or is killed before the server is contacted, the files remain deleted without any trace,” he continues.
“After the client restarts again, it only sees there are some files missing and syncs this new state with the server.
“Unfortunately for me, Dropbox only keeps a copy of [the] deleted files for 30 days and I found out about this event after two months,” he adds.
Dropbox has since been able to reinstate 1,463 of his deleted files, and given him credit that he can spend on other services the firm provides.
However, he’s made a series of recommendations to Dropbox about how they can improve their service, and prevent similar incidents affecting other users.
They include making improvements to Selective Sync that mean if the process fails at any point users’ data isn’t jeopardised. He'd also like to see Dropbox keep a history of people’s deleted files for as long as their storage quota allows.
He also advocates the use of machine learning techniques to monitor strange activity on people’s accounts.
“Most of my activity over the years consists of adding [a] large number of new files and changing/deleting a small number of files from time to time. A sudden deletion of 8,343 files is surely a strange activity in this context,” he added.
Cloud Pro approached Dropbox for comment on this story, but had not received a response at the time of publication
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