Some of the popular organizations that hold Big Data are as follows:
- Facebook: It has 40 PB of data and captures 100 TB/day
- Yahoo!: It has 60 PB of data
- Twitter: It captures 8 TB/day
- EBay: It has 40 PB of data and captures 50 TB/day
How much data is considered as Big Data differs from company to company. Though true that one company's Big Data is another's small, there is something common: doesn't fit in memory, nor disk, has rapid influx of data that needs to be processed and would benefit from distributed software stacks. For some companies, 10 TB of data would be considered Big Data and for others 1 PB would be Big Data. So only you can determine whether the data is really Big Data. It is sufficient to say that it would start in the low terabyte range.
Also, a question well worth asking is, as you are not capturing and retaining enough of your data do you think you do not have a Big Data problem now? In some scenarios, companies literally discard data, because there wasn't a cost effective way to store and process it. With platforms as Hadoop, it is possible to start capturing and storing all that data.