&quot;It Depends.&quot; If youre doing &quot;random&quot; writes down to the block dev, like updating a filesystem, it can be very bad. You&#x27;ll end up hitting the read&#x2F;update&#x2F;write cell issues and block other concurrent access. In general I&#x27;d worry (expect total throughput to go down, and tail latency way up) around a 10-20% write:read ratio. Conversely if youre doing sane sequential writes, say log structure merges with a 64-256KB chunk size, Id expect much less impact to your read latencies.