Thanks Eric, unfortunately still getting a completely different number!
ashley cook, I outputted the size of each snapshot which gives me the 7TB:
(0151748487)_prd_std_T3_b28_01_r.26705 13
smvi_Clayton-std-daily-01_novmsnap_20120609222000 219
smvi_Clayton-std-daily-01_novmsnap_20120610222000 223
smvi_Clayton-std-daily-01_novmsnap_20120611222000 476
smvi_Clayton-std-daily-01_novmsnap_20120613222000 256
smvi_Clayton-std-daily-01_novmsnap_20120614222000 296
smvi_Clayton-std-daily-01_novmsnap_20120615222000 491
smvi_Clayton-std-daily-01_novmsnap_20120616222000 394
smvi_Clayton-std-daily-01_novmsnap_20120617222000 249
smvi_Clayton-std-daily-01_novmsnap_20120618222000 275
smvi_Clayton-std-daily-01_novmsnap_20120619222000 234
smvi_Clayton-std-daily-01_novmsnap_20120620222006 337
smvi_Clayton-std-daily-01_novmsnap_20120622222000 403
smvi_Clayton-std-daily-01_novmsnap_20120623222000 224
smvi_Clayton-std-daily-01_novmsnap_20120624222001 226
smvi_Clayton-std-daily-01_novmsnap_20120625222000 343
smvi_Clayton-std-daily-01_novmsnap_20120627222000 258
smvi_Clayton-std-daily-01_novmsnap_20120628222000 256
smvi_Clayton-std-daily-01_novmsnap_20120629222000 365
smvi_Clayton-std-daily-01_novmsnap_20120630222000 265
smvi_Clayton-std-daily-01_novmsnap_20120701222000 136
smvi_Clayton-std-daily-01_novmsnap_20120702222000 143
smvi_Clayton-std-daily-01_novmsnap_20120703222000 137
smvi_Clayton-std-daily-01_novmsnap_20120704222000 139
smvi_Clayton-std-daily-01_novmsnap_20120705222000 151
smvi_Clayton-std-daily-01_novmsnap_20120706222001 242
smvi_Clayton-std-daily-01_novmsnap_20120707222000 153
smvi_Clayton-std-daily-01_novmsnap_20120708222000 139
smvi_Clayton-std-daily-01_novmsnap_recent 84