TLDR:
I don’t use windows, but I found the folder—it’s located by default under the config folder, wherever that folder may be. Perhaps the docker container puts it to the share along with the data folder (I don’t use docker either, as you might have guessed. 
Details:
I’ve setup that node like so (those are the only flags I provided to setup command):
storagenode setup \
--storage.path "${STORAGE_PATH}" \
--config-dir "${CONFIG_DIR}" \
--identity-dir "${IDENTITY_DIR}" \
--operator.email "${OPERATOR_EMAIL}" \
--console.address "${CONSOLE_ADDRESS}" \
--operator.wallet "${OPERATOR_WALLET}" \
--operator.wallet-features "${OPERATOR_WALLET_FEATURES}" \
--contact.external-address "${CONTACT_EXTERNAL_ADDRESS}" \
--storage.allocated-disk-space "${STORAGE_ALLOCATED_DISK_SPACE}"
Looking at the generated configuration file in the CONFIG_DIR, I see this: (note, it’s commented out, I never edited the config file manually)
# path to store order limit files in
# storage2.orders.path: /mnt/storj-two/config/orders
The value is defined but commented out, apparently to indicate the default. So, while it can be overridden, by default orders folder is placed under the config folder. On my other node, I did not put it under the data folder, and that’s why I was unable to find it. For my second node, I put the config folder along with identity folder into the data folder, and it’s of course there.
Thank you all for clarification.
The db file on my node has a modification time of Dec 27, last year, so it was being used at least up until two weeks ago:
% ls -alt /mnt/storj-two/orders.db
-rw-r--r-- 1 storj storj 32768 Dec 27 18:13 /mnt/storj-two/orders.db
So was it two weeks ago when the .db stopped being used, and storage node now relies purely on the file system to track orders?
perhaps the “fix” should be another sheduled job to do something like find /.../orders -mtime +4 --delete to nuke stale old files?