Systems and methods for compression, formatting, and migration of data for data storage systems are disclosed. In some embodiments, data repacking can be used in any situation where embedded metadata needs to be accessed, such as during data migration, and where the underlying data is encrypted. In some embodiments, performance is increased because encrypted data is repacked without first performing decryption. In addition, data may also be compressed and repacking can be performed without performing decompression. Advantageously, there is no need to retrieve or wait for the availability of encryption key (or keys) or expand resources in decrypting (and decompressing) data before repacking it and encrypting repacked data. Available capacity for storing user data, reliability, and performance of the data storage system can be increased.