Index: lsm-test/lsmtest_main.c
==================================================================
--- lsm-test/lsmtest_main.c
+++ lsm-test/lsmtest_main.c
@@ -1331,29 +1331,33 @@
 
   return rc;
 }
 
 static int do_insert(int nArg, char **azArg){
-  const char *zConfig = 0;
   const char *zDb = "lsm";
   TestDb *pDb = 0;
   int i;
   int rc;
   const int nRow = 1 * 1000 * 1000;
 
   DatasourceDefn defn = { TEST_DATASOURCE_RANDOM, 8, 15, 80, 150 };
   Datasource *pData = 0;
 
-  if( nArg>2 ){
-    testPrintError("Usage: insert ?DATABASE? ?LSM-CONFIG?\n");
+  if( nArg>1 ){
+    testPrintError("Usage: insert ?DATABASE?\n");
     return 1;
   }
   if( nArg==1 ){ zDb = azArg[0]; }
-  if( nArg==2 ){ zConfig = azArg[1]; }
 
   testMallocUninstall(tdb_lsm_env());
-  rc = tdb_open(zDb, 0, 1, &pDb);
+  for(i=0; zDb[i] && zDb[i]!='='; i++);
+  if( zDb[i] ){
+    rc = tdb_lsm_open(zDb, "testdb.lsm", 1, &pDb);
+  }else{
+    rc = tdb_open(zDb, 0, 1, &pDb);
+  }
+
   if( rc!=0 ){
     testPrintError("Error opening db \"%s\": %d\n", zDb, rc);
   }else{
     InsertWriteHook hook;
     memset(&hook, 0, sizeof(hook));
@@ -1360,13 +1364,10 @@
     hook.pOut = fopen("writelog.txt", "w");
 
     pData = testDatasourceNew(&defn);
     tdb_lsm_config_work_hook(pDb, do_insert_work_hook, 0);
     tdb_lsm_write_hook(pDb, do_insert_write_hook, (void *)&hook);
-    if( zConfig ){
-      rc = tdb_lsm_config_str(pDb, zConfig);
-    }
 
     if( rc==0 ){
       for(i=0; i<nRow; i++){
         void *pKey; int nKey;     /* Database key to insert */
         void *pVal; int nVal;     /* Database value to insert */

Index: src/lsm_file.c
==================================================================
--- src/lsm_file.c
+++ src/lsm_file.c
@@ -98,17 +98,29 @@
 ** is different from the uncompressed format where the first and last pages
 ** on each block are 4 bytes smaller than the others.
 **
 ** Pages are stored in variable length compressed form, as follows:
 **
-**     * Number of bytes in compressed page image, as a 3-byte big-endian
-**       integer.
+**     * 3-byte size field containing the size of the compressed page image
+**       in bytes. The most significant bit of each byte of the size field
+**       is always set. The remaining 7 bits are used to store a 21-bit
+**       integer value (in big-endian order - the first byte in the field
+**       contains the most significant 7 bits). Since the maximum allowed 
+**       size of a compressed page image is (2^17 - 1) bytes, there are
+**       actually 4 unused bits in the size field.
+**
+**       In other words, if the size of the compressed page image is nSz,
+**       the header can be serialized as follows:
+**
+**         u8 aHdr[3]
+**         aHdr[0] = 0x80 | (u8)(nSz >> 14);
+**         aHdr[1] = 0x80 | (u8)(nSz >>  7);
+**         aHdr[2] = 0x80 | (u8)(nSz >>  0);
 **
 **     * Compressed page image.
 **
-**     * The number of bytes in the compressed page image, again as a 3-byte
-**       big-endian integer.
+**     * A second copy of the 3-byte record header.
 **
 ** A page number is a byte offset into the database file. So the smallest
 ** possible page number is 8192 (immediately after the two meta-pages).
 ** The first and root page of a segment are identified by a page number
 ** corresponding to the byte offset of the first byte in the corresponding
@@ -115,22 +127,21 @@
 ** page record. The last page of a segment is identified by the byte offset
 ** of the last byte in its record.
 **
 ** Unlike uncompressed pages, compressed page records may span blocks.
 **
-** TODO:
-**
 ** Sometimes, in order to avoid touching sectors that contain synced data
 ** when writing, it is necessary to insert unused space between compressed
 ** page records. This can be done as follows:
 **
-**     * For less than 4 bytes of empty space, a series of 0x00 bytes.
+**     * For less than 6 bytes of empty space, a series of 0x00 bytes.
 **
-**     * For 4 or more bytes, the block of free space begins with an 
-**       0x01 byte, followed by a varint containing the total size of the 
-**       free space. Similarly, it ends with an (ABCD -> BCDA) transformed
-**       varint an a final 0x01 byte.
+**     * For 6 or more bytes of empty space, a record similar to a 
+**       compressed page record is added to the segment. A padding record
+**       is distinguished from a compressed page record by the most 
+**       significant bit of the second byte of the size field, which is
+**       cleared instead of set. 
 */
 #include "lsmInt.h"
 
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -933,19 +944,24 @@
   }
   return rc;
 }
 
 /*
-** Encode and decode routines for 24-bit big-endian integers.
-*/
-static u32 lsmGetU24(u8 *aBuf){
-  return (((u32)aBuf[0]) << 16) + (((u32)aBuf[1]) << 8) + ((u32)aBuf[2]);
-}
-static void lsmPutU24(u8 *aBuf, u32 iVal){
-  aBuf[0] = (u8)(iVal >> 16);
-  aBuf[1] = (u8)(iVal >>  8);
-  aBuf[2] = (u8)(iVal >>  0);
+** Encode and decode routines for record size fields.
+*/
+static void putRecordSize(u8 *aBuf, int nByte, int bFree){
+  aBuf[0] = (u8)(nByte >> 14) | 0x80;
+  aBuf[1] = ((u8)(nByte >>  7) & 0x7F) | (bFree ? 0x00 : 0x80);
+  aBuf[2] = (u8)nByte | 0x80;
+}
+static int getRecordSize(u8 *aBuf, int *pbFree){
+  int nByte;
+  nByte  = (aBuf[0] & 0x7F) << 14;
+  nByte += (aBuf[1] & 0x7F) << 7;
+  nByte += (aBuf[2] & 0x7F);
+  *pbFree = !!(aBuf[1] & 0x80);
+  return nByte;
 }
 
 static int fsSubtractOffset(FileSystem *pFS, i64 iOff, int iSub, i64 *piRes){
   i64 iStart;
   int iBlk;
@@ -1013,11 +1029,12 @@
   if( fsAllocateBuffer(pFS) ) return LSM_NOMEM;
 
   rc = fsReadData(pFS, iOff, aSz, sizeof(aSz));
 
   if( rc==LSM_OK ){
-    pPg->nCompress = (int)lsmGetU24(aSz);
+    int bFree;
+    pPg->nCompress = (int)getRecordSize(aSz, &bFree);
     rc = fsAddOffset(pFS, iOff, 3, &iOff);
     if( rc==LSM_OK ){
       if( pPg->nCompress>pFS->nBuffer ){
         rc = LSM_CORRUPT_BKPT;
       }else{
@@ -1319,12 +1336,13 @@
   i64 iRead;
 
   rc = fsSubtractOffset(pFS, iOff, sizeof(aSz), &iRead);
   if( rc==LSM_OK ) rc = fsReadData(pFS, iRead, aSz, sizeof(aSz));
   if( rc==LSM_OK ){
-    int nSz = lsmGetU24(aSz) + sizeof(aSz)*2;
-    rc = fsSubtractOffset(pFS, iOff, nSz, piPrev);
+    int bFree;
+    int nSz = getRecordSize(aSz, &bFree);
+    rc = fsSubtractOffset(pFS, iOff, nSz + sizeof(aSz)*2, piPrev);
   }
 
   return rc;
 }
 
@@ -1770,11 +1788,11 @@
 
       /* Compress the page image. */
       rc = fsCompressIntoBuffer(pFS, pPg);
 
       /* Serialize the compressed size into buffer aSz[] */
-      lsmPutU24(aSz, pPg->nCompress);
+      putRecordSize(aSz, pPg->nCompress, 0);
 
       /* Write the serialized page record into the database file. */
       pPg->iPg = fsAppendData(pFS, pPg->pSeg, aSz, sizeof(aSz), &rc);
       fsAppendData(pFS, pPg->pSeg, pFS->aBuffer, pPg->nCompress, &rc);
       fsAppendData(pFS, pPg->pSeg, aSz, sizeof(aSz), &rc);