Storage system using fast storage and log-structured storage

A computer storage apparatus comprising:

• a controller means for performing data operations in a storage array means for storing data;
• a cache means for caching data;
• and
• the storage array means comprises a first sub-array means for storing data using a log-structured algorithm and a fast storage sub-array means for storing data redundant to data stored in the first sub-array means, wherein the fast storage sub-array means includes one or more fast storage devices,
• wherein data is operable to be written from the cache means to the first sub-array means and the fast storage sub-array means.

A method of recovering from a failed device in a storage system having at least one log-structured storage device and at least one fast storage device storing data redundant to data stored in the at least one log-structured storage device, the method comprising steps of:

• determining whether the at least one log-structured storage device failed;
• reading data from the at least one fast storage device in response to the at least one log-structured storage device being failed, the read data including data redundant to the data stored on the at least one failed log-structured storage device;
• and
• writing the redundant data to a log-structured storage device that is operative in the storage system.

In a computer storage system including at least one log-structured storage device and at least one fast storage device storing data redundant to data stored in the at least one log-structured storage device, wherein the at least one log-structured storage device is divided into extents for storing data, a method for cleaning an extent comprises steps of:

• identifying valid data in an extent being cleaned in the log-structured storage device;
• retrieving a copy of the valid data from the at least one fast storage device;
• and
• appending the copy of the valid data to a current extent in the at least one log-structured storage devices,
• wherein the current extent comprises one or more of a current extent in the at least one log-structured storage device, a clean extent nearest to the previous current extent, and an extent with a greatest number of invalid blocks at the time the previous current extent became full.

A method of performing data operations in a storage system comprising at least one log-structured storage device and at least one fast storage device, the method comprising steps of:

• receiving a request to perform a data operation;
• determining whether the request provokes a write operation on the storage system;
• in response to the request provoking a write operation, writing data to the at least one log-structured storage device and writing redundant data to at least one fast storage device;
• determining whether the request provokes a read operation on the storage system;
• determining whether the at least one fast storage device is busy in response to the request provoking a read operation;
• reading data from the at least one fast storage device in response to the at least one fast storage device not being busy;
• and
• reading data from any one of the at least one log-structured storage device and the at least one fast storage device in response to the at least one fast storage device being busy.