Arvados

h1. Untrashing lost blocks

In some cases it is possible to recover data blocks that have been trashed by keep-balance (due to a bug or an install/config error).

If you suspect blocks have been trashed erroneously, you should immediately:

# On all keepstore servers: set EmptyTrashInterval to a long time like 2400h

# On all keepstore servers: restart keepstore

# Stop the keep-balance service

When you think you have corrected the underlying problem, you should:

# Set LostBlocksFile to a suitable value (perhaps "/tmp/keep-balance-lost-blocks.txt") in your keep-balance config

# Start keep-balance

After keep-balance completes its first sweep, inspect /tmp/keep-balance-lost-blocks.txt. If it's not empty, you can request all keepstores to untrash any blocks that are still recoverable with a script like this:

<pre><code class="bash">

#!/bin/bash

set -e

# see Client.AuthToken in /etc/arvados/keep-balance/keep-balance.yml

token=xxxxxxx-your-system-auth-token-xxxxxxx

# all keep server hostnames

hosts=(keep0 keep1 keep2 keep3 keep4 keep5)

while read hash pdhs; do

    echo "${hash}"

    for h in ${hosts[@]}; do

        if curl -fgs -H "Authorization: Bearer $token" -X PUT "http://${h}:25107/untrash/$hash"; then

            echo "${hash} ok ${host}"

        fi

    done

done < /tmp/keep-balance-lost-blocks.txt

</code></pre>