You have 6Gb RAM and a terabyte HDD. I'll assume you have allocated some swap drive to expand your total memory to more than 6Gb.
The current rounds of attacks on the Ethereum network started on the morning of the Devcon2 conference.
This first attack targeted a
geth memory bug - see Security alert – All geth nodes crash due to an out of memory bug.
The second round of attacks targeted a "cheap" method of using a lot of hard disk resources - see The Ethereum network is currently undergoing a DoS attack and Transaction spam attack: Next Steps.
The result of the attacks above is to slow down the Ethereum network clients by requiring more memory to process the spam transactions, more disk accesses to retrieve the data required to process the spam transactions and more CPU usage to process the spam transactions.
My virtual server is constantly dropping out due to an out-of-memory error - it only has 4Gb RAM + 4 GB swap drive, but it runs on SSD drives. Both
geth and Parity run out of memory. With Parity, I've just restarted it and have not encountered the IncompleteDatabase error you experienced (which requires a clean out and full sync again).
My solo mining node has 8Gb RAM + 8 Gb swap drive and runs on 250 Gb SSD on a low spec Intel(R) Core(TM) i3-6100 CPU @ 3.70GHz and it has been keeping up with the syncing (except for the first memory bug attack).
- If possible, switch from your 1 Tb HDD to a SSD. Otherwise just put up with the processing speed due to the second round of attacks.
- Before restarting a sync, remove your old chain data and if you are using
geth, sync with the command
geth --cache=1024 --fast console. You can try a smaller cache size, but if you have 6Gb RAM + 6Gb swap drive,
--cache=1024 should be good.
- Update all your software - see HARD FORK IN LESS THAN 24 HOURS. UPGRADE YOUR CLIENT [OFFICIAL ETHEREUM UPDATE LINKS] for the most recent executables.
If you are using
geth on Linux, use the command
geth removedb, or delete
~/.ethereum/chaindata to clear your chain data. On Windows, search this site for the appropriate directory to clear.
From past experience, if
geth crashes while processing the fast and non-fast sync, the chain data does not get corrupted (unlike the particular bug in Parity that you encountered).
See Ethereum mining after fast sync about fast sync restarting. Your fast sync has to complete a certain stage otherwise it will have to restart syncing from the beginning.
Just persist, it will eventually work. Good luck.