▁of ▁modern ▁file ▁systems , ▁ext 3 ▁does ▁not ▁have ▁native ▁support ▁for ▁snap sh ots , ▁the ▁ability ▁to ▁quickly ▁capture ▁the ▁state ▁of ▁the ▁filesystem ▁at ▁arbitrary ▁times . ▁Instead , ▁it ▁re lies ▁on ▁less - space - efficient , ▁volume - level ▁snap sh ots ▁provided ▁by ▁the ▁Linux ▁L VM . ▁The ▁Next 3 ▁file ▁system ▁is ▁a ▁modified ▁version ▁of ▁ext 3 ▁which ▁offers ▁snap sh ots ▁support , ▁yet ▁retain s ▁compatibility ▁with ▁the ▁ext 3 ▁on - disk ▁format . ▁ ▁No ▁check sum ming ▁in ▁journal ▁ext 3 ▁does ▁not ▁do ▁check sum ming ▁when ▁writing ▁to ▁the ▁journal . ▁On ▁a ▁storage ▁device ▁with ▁extra ▁cache , ▁if ▁bar rier = 1 ▁is ▁not ▁enabled ▁as ▁a ▁mount ▁option ▁( in ▁/ etc / f stab ), ▁and ▁if ▁the ▁hardware ▁is ▁doing ▁out - of - order ▁write ▁caching , ▁one ▁runs ▁the ▁risk ▁of ▁severe ▁filesystem ▁cor ruption ▁during ▁a ▁crash . ▁This ▁is ▁because ▁storage ▁devices ▁with ▁write ▁c aches ▁report ▁to ▁the ▁system ▁that ▁the ▁data ▁has ▁been ▁completely ▁written , ▁even ▁if ▁it ▁was ▁written ▁to ▁the ▁( vol atile ) ▁cache . ▁ ▁If ▁hard ▁disk ▁writes ▁are ▁done ▁out - of - order ▁( due ▁to ▁modern ▁hard ▁dis ks ▁caching ▁writes ▁in ▁order ▁to ▁am ort ize ▁write ▁spe eds ), ▁it ▁is ▁likely ▁that ▁one ▁will ▁write ▁a ▁commit ▁block ▁of ▁a ▁transaction ▁before ▁the ▁other ▁relevant ▁blocks ▁are ▁written . ▁If ▁a ▁power