What does the Monero wallet do during I/O bound initial sync?

Question

Quote from How Long For Initial Sync to Complete

Sync'ing speed really depends on your hardware and Internet connection. The blockchain is 20+ gigs and there's some processing that happens for each block - so it's going to take a while.

SSD drives make a huge difference. Older rotational drives are slow.

There is huge disk traffic on MacBook:

but the blockchain is much smaller:

> pwd
/Users/Fyodor/.bitmonero
> du -sh *
1.6M    bitmonero.log
6.6G    lmdb
132K    p2pstate.bin

What's the exact processing it does? How to move my wallet (official GUI wallet) from MacBook to Raspberry when finished?

Answer 1

It's verifying transactions for blocks past the set of known hashes (past 1.2 million), and storing tx and block data in the database. It can also be serving some blocks to others, but that's typically not much compared to the load from syncing. If you have a wallet connected, the wallet will also compete to get the blockchain lock so it can refresh blocks. It's best to keep the wallet off while syncing.

Monero uses LMDB, a fast key/value database, but writing new data to the database isn't just appending the block blob at the end of the file, as it is structured, with some tables being sorted in a tree.

As for moving the database once done, it's as simple as stopping the dameon and copying the data.mdb file. It's platform independent except for endianness.