Techniques for extending a write cache

One or more non-transitory computer readable media comprising code stored thereon that, when executed, performs a method comprising:

• receiving a first set of write operations;
• persistently recording, in a write cache or log, the first set of write operations, wherein said recording each write operation of the first set includes persistently recording information describing said each write operation in a corresponding page descriptor (PDESC) of a PDESC pool and persistently storing a corresponding write data page written by said each write operation in a corresponding page buffer (PB) of a PB pool;
• selecting, in accordance with one or more criteria, a first plurality of write data pages stored in a first plurality of PBs of the PB pool for demotion to a first physical large block (PLB) of a PLB pool of non-volatile storage included in a storage tier of backend (BE) non-volatile storage, wherein each of the write data pages of the first plurality of write data pages selected denotes content written by a corresponding one of a first plurality of write operations of the first set;
• responsive to said selecting, persistently storing the first plurality of write data pages from the first plurality of PBs of the PB pool in the first PLB;
• and
• updating a first plurality of PDESCs associated with the first plurality of write data pages of the first plurality of write operations to reference corresponding storage locations in the first PLB rather than the first plurality of PBs.

A system comprising:

• one or more processors;
• and
• one or more memories comprising code stored thereon that, when executed, performs a method comprising:
• receiving a first set of write operations;
• persistently recording, in a write cache or log, the first set of write operations, wherein said recording each write operation of the first set includes persistently recording information describing said each write operation in a corresponding page descriptor (PDESC) of a PDESC pool and persistently storing a corresponding write data page written by said each write operation in a corresponding page buffer (PB) of a PB pool;
• selecting, in accordance with one or more criteria, a first plurality of write data pages stored in a first plurality of PBs of the PB pool for demotion to a first physical large block (PLB) of a PLB pool of non-volatile storage included in a storage tier of backend (BE) non-volatile storage, wherein each of the write data pages of the first plurality of write data pages selected denotes content written by a corresponding one of a first plurality of write operations of the first set;
• responsive to said selecting, persistently storing the first plurality of write data pages from the first plurality of PBs of the PB pool in the first PLB;
• and
• updating a first plurality of PDESCs associated with the first plurality of write data pages of the first plurality of write operations to reference corresponding storage locations in the first PLB rather than the first plurality of PBs.