One or more techniques and/or systems are provided for performing host side deduplication. Host side deduplication may be performed upon writeable data within a write request received at a host computing device configured to access data stored by a storage server. The host side deduplication may be performed at the host computing device to determine whether the writeable data is already stored by the storage server based upon querying a host side cache comprising data stored by a storage server and/or a data structure comprising unique signatures of data stored by the storage server. If the writeable data is stored by the storage server, then a deduplication notification excluding the writeable data may be sent to the storage server, otherwise a write command comprising the writeable data may be sent. Accordingly, unnecessary network traffic of redundant data already stored by the storage server may be reduced.