The maximum size of a BLOB field is limited to 4GB, regardless of whether the server is 32-bit or 64-bit. (The internal structures related to BLOBs maintain their own 4-byte counters.) For a page size of 4 KB (4096 bytes) the maximum size is lower — slightly less than 2GB.
However, blobs can be a lot larger than 4GB, but with restricted functionality (e.g. OCTET_LENGTH reports incorrect length, seeks don't work beyond 4GB - 1, etc). In addition the maximum size of a blob on page size 4KB is slightly less than 4GB (exact size depends on stream blob or the segment sized used), not slightly less than 2GB.
The language references on blobs currently say:
However, blobs can be a lot larger than 4GB, but with restricted functionality (e.g.
OCTET_LENGTH
reports incorrect length, seeks don't work beyond 4GB - 1, etc). In addition the maximum size of a blob on page size 4KB is slightly less than 4GB (exact size depends on stream blob or the segment sized used), not slightly less than 2GB.