The claim is that someone stole 10PB of data from a Chinese Supercomputer Center.
I have some, ahem, small, experience with large data storage ( first person to build a multi-PB file system for NASA in the 1990s, first person to move one TB/sec while at Seagate over 12 years ago, etc ).
10PB of data is 11,258,999,068,426,240 8bit bytes... or 90,071,992,547,409,920 bits ( not including any message encapsulation via TCP/IP ).
Let's assume the hacker had access to a 100 Gbit link to this supercomputer site AND that no one would notice 100Gbit/sec transfer from this site to someplace remote. Dividing it out it would take almost 10 full days pulling data at 100Gbit/sec to capture all of the data, not to mention you would need a 10 PB data store to save it for later ( while possible these days with cheaper storage, it would still cost a lot of $$$ ).
Entirely possible if everyone was asleep at the wheel in the Chinese supercomputer center... but very unlikely. Not to mention at 100 Gbit/sec links and 10PB data stores are expensive.
I would rate this as very unlikely.
Of course, they might hide the transfer by using much smaller transfer rates, but then the opportunity for the operations staff to notice the transfer over 100 days or longer would be much higher.
Not to mention that that IF this data was detailed records of every person on earth right now ( 8.3 billion of us ) that this would represent over a megabyte of data, addresses, DOB, phone numbers, photos, etc on each and every person. You can capture a lot about someone with 1MB of storage... so this will more likely be raw data from instruments like particle accelerators, satellite images, etc. Most of which is not very useful to hackers.
Makes for a good headline and Petabyte is so large that it is hard for people to imagine what that really means.