2012 2d Iteratoal Coferece o Idustral Techology ad Maagemet (ICITM 2012) IPCSIT vol 49 (2012) (2012) IACSIT Press, Sgapore DOI: 107763/IPCSIT2012V495 2 A Parallel Trasmsso Remote Backup System Che Yu College of Computer Scece, Schua Uversty, Chegdu, Cha Abstract A parallel trasmsso remote backup system s preseted ths thess Ths system could offer real-tme motorg for data of user s dsk partto, ad trasmt the chaged data to remote backup server by parallel approach Whe data loss occurs, ths system could recover the backup data to the local dsk partto Ths system also offer a wrte order costrats ad data cosstece to makesure the data s correct Keywords: Backup; parallel; recover; cosstece 1 Itroducto The atteto of the data securty s growg today s formatzato hghly developed socety loss or corrupto wll brg estmable loss may walks of lfe The dsaster recovery system become more ad more commo The prcple of most remote dsaster recovery system s create the backup of target dsk o a removable dsk or etworked locato, data the target dsk ad the backup dsk become cosstet by resychrozato Ths paper propose a parallel trasmsso remote backup system[1] Dfferet from other backup system s ths system uses a parallel trasmsso ad use wrte order costrats to esure the data s correct Ths system also offer a data cosstecy to make sure the backup data s useful 2 System Module Local backup server Remote backup server Local backup server motorg module local sychrozato module local recover module packet trasmsso module teret remote backup server local sychrozato module remote sychrozato module remote recover module cosstecy module packet processg module Target dsk cache Fg 1: System module structure Image dsk The system s dvded to motorg module, sychrozato module, recovery module, packet trasmsso module, packet processg module, cosstecy module Correspodg author E-mal address: lacecheyu@gmalcom 285
Sychrozato module dvded to local sychrozato module ad remote sychrozato module[2] Ths module copy target dsk data to mage dsk Esure the target dsk cosstet wth the mage dsk whe the task start rug Recovery module dvded to local recovery module ad remote recovery module Whe data loss occurs ths module lock the local dsk ad copy mage dsk data to target dsk Esure dsk data recovery to the state before the dsaster Motorg module tercepts dsk wrte operato by volume flter drver[3], storage the correspodg data to the cache o the local server Packet trasmsso module trasfer data packet to remote server, use the parallel trasmsso to mprove the speed Packet processg module receve the data packet from the local server Read formato from the packet ad wrte t to the mage Use wrte order costrats to respose data assocato ad data depedet 3 Task Process Crate task sychrozato Motor target dsk Trasfer data packet Processg data packet Wrte backup dsk Fg 2: Task rug process recover Ths backup system create task for every target dsk, sychroze motorg ad recover the dsk by operate the task User create a task for target dsk o the operate platform, the the system create a mage dsk the remote server storage medum Local sychrozato module create a buffer memory for the task to restore the task formato [4]Remote sychrozato module create a mage dsk the remote server, the make the target dsk ad mage dsk data cosstece by sychrozato Whe the sychrozato s complete, the motorg module to beg the motorg of I/O operate at the correspodg dsk partto, ad trasfer the motorg data to remote server by teret packet processg module read data packet s formato ad wrte t to the mage, make sure the mage dsk ad target dsk be data cosstece Whe data loss occurs, user beg dsaster recover operate Recover module lockg target dsk The data the mage dsk wll be coped to the target dsk, to make dsk data recovery to the state before the dsaster 4 Sychrosm Begg the motorg module to motor the correspodg dsk partto, you eed to create a storage medum the mrror, ad through data sychrozato to mrror data correspodg to the same dsk partto The sychrozato clude complete sychrozato ad dversty sychrozato Local backup server Target dskx B 1 B2 B block B read head B B packet packe t1 packe t2 packe t B =B wrte Image dsk x B1 B B CID TID NUM Parallel trasmsso Fg 3: Sychrosm process I the begg of sychrozato, local sychrozato module partto the target dsk to umerous data block[5] Suppose the target dsk amed X, the aggregate Ld clude dsk X s data, dvded Ld to N- data block B B 1 2 B, ad cotet the followg codtos: 286
Ld B, B 1 1 Meawhle, create a data mrrorg the storage mage for the task Suppose the mage dsk amed X', the aggregate Rd clude the data of dsk X', dvded Rd to M-data block B' B' B' 1 2 m, ad cotet the followg codtos: m 1 1 Rd B ', B ' m, m Local sychrozato module read data block B, add a header fle HEAD, HEAD s defed as: HEAD={CID,TID,NUM} The CID s the socket fle descrptor of the coect the task whch the data block correspodg belogs The TID s the task d of the task whch the data block correspodg The NUM s the umber of the data block, NUM= Set the data block wth header fle to the remote server oe by oe Remote sychrozato module read the header fle frst, fd the mage dsk locato by CID ad TID, ad used NUM to fd the correspodg data block the mage dsk B ' whch cotet NUM=, copy the data the B to B ' Whe all the data blocks are set to the remote server ad be processed, the data the mage dsk ad the target dsk be cosstecy The dversty sychrozato ca be used to mprove the speed f the task s t frst ru The dversty sychrozato got the same data copyg process wth the complete sychrozato The dfferece s the dversty sythrozato calculated dgest value for all data block before data copy Defe a structure S(B ) to store the data block B s dgest value Local sychrozato module calculate all the data block both the target dsk ad mage dsk Obta two queue store the dgest value S(B ) from target dsk ad S(B ') mage dsk The module compare the value of S(B ) ad the value of S(B ') wth the same umber, for example S(B 5 ) ad S(B 5 ') If the value of S(B ) ad the value of S(B ') are equal, gore the data block B I the opposte case the module trasfer the block B ad copy the data of B to B ', just lke the complete sychrozato 5 Wrte Order Costrats After the text edt has bee completed, the paper s ready for the template Duplcate the template fle by usg the Save As commad, ad use the amg coveto prescrbed by your coferece for the ame of your paper I ths ewly created fle, hghlght all of the cotets ad mport your prepared text fle You are ow ready to style your paper Ths system use parallel trasmsso to ehace trasfer speed The packet order whch packet processg module receved s t the correct order Applcatos mata the cosstecy of ther data by keepg track of modfcatos of ther data sets specal places I case of a system crash, the formato these jourals s suffcet to brg the data set to a cosstet state aga The applcato must esure that the wrte operato to update the joural s fshed before the update of the assocated data set takes place The applcatos use the fsyc or the fdatasyc[6] system calls to mpose wrte order costrats By usg these calls the applcatos are delayed utl all pedg wrte requests have bee processed If the prmary ode fals, the system have to restart from the curret state of the secodary ode's dsk For example, the system do t eed a defed order of the wrte operatos of data blocks B 0, B 1, B 2, B 3 ad B 4, sce they were ssued before ay of these IO requests had bee dow But t s possble that the applcato ssued the wrte request for block B 5 because the wrte operatos of B 0 ad B 3 were fshed Oly the applcato kows f ths s a real wrte-after-wrte depedecy, therefore we must ot volate a sgle possble depedecy Ths system approach s to keep a hstory of all recetly set wrte requests As soo as a sgle block of these fshes IO, a wrte barrer must be ssued, ad the hstory s cleared 287
Trasmsso queue Target dsk barrer B0 B3 B0 B0 B1 B1 B2 B2 B3 B3 B4 B4 B5 B5 tme B5 Receve queue Image dsk wrte receve depedecy Fg 4: Wrte order costrats I the above example the blocks B 0, B 1, B 2, B 3, ad B 4 are added to the hstory set Wth the completo of B 3 's wrte operato the hstory set gets cleared ad a wrte barrer s ssued after block B 4 The secodary ode ca ow receve blocks ad commt them to ts local IO subsystem mmedately If t receves a wrte barrer, t wats utl all ts pedg wrte requests are fshed before t processes ay further requests 6 Cosstecy Checkg After the sychrozato has bee completed, the cosstecy g module g the data betwee target dsk ad mage dsk The defto of data cosstecy g as follows: Target data collecto P={a,b,c}, backup data collecto P ={a,b,c } Status of target data collecto P at tme T s P =(a,b,c ) Status of backup data collecto P at tme T s P =(a,b,c ) If T =T' P =P',meas cosstecy g pass, Or T =T' P P' meas data the targer dsk ad mage dsk s t cosstece 61 Algorthm descrpto Set curret motorg dsk data collecto s D, remote backup dsk data collecto s D' Therefore D' s a mage for D ad D D' s a bjectve mappg Aggregate D 1,D 2, D s subaggragate of D, D 1 ',D 2 ', D ' s subaggragate of D', ad cotetmet follow codtos: D D, D, D ' D', D ' 1 1 1 1 1 1 2 2 D D' D D ', D D ',, D D ' Defe fucto f(x) to fd a summary of the value of the aggregate ad get followg expresso: The formulato of the cosstecy s: Brach A: T T ', D D, D ' D, j j j D D' f ( D ) f ( D ),, f ( D ) f ( D' ) 1 1 j f ( D ) f ( D ') D D' meas the target data as same as the mage data, the data cosstecy j be successful Brach B: T T ', D D, D ' D, j j f ( D ) f ( D ') D D' meas the target data ad the mage data s t cosstece For backup system based o teret, because of et trasfer, the chage of data collecto at tme pot T wll reflect to the backup data at the T'=T +ΔT(ΔT>0) tme The fomulato of data cosstecy o the teret s: Brach A: T T ' T, D D, D ' D, j j j j f ( D ) f ( D ') D D' meas the target data as same as the mage data Brach B: j 288
T T ' T, D D, D ' D, j j f ( D ) f ( D ') D D' meas the target data ad the mage data s t cosstece 62 Cosstecy mplemet All the data cosstecy clude volume copy servce, packet trasmsso module ad cosstecy module, t s follows the process: Beg cosstecy module, requre packet trasmsso module stop trasfer data Cosstecy module make sure the data dspatch s stopped, form the volume copy servce create a sapshot[7] The cache get the tme of create sapshot, sed the data whch the store tme before create sapshot cosstecy module beg cosstecy betwee local dsk ad remote dsk The complete, form the volume copy servce destroy the sapshot ad ote packet trasmsso module beg trasfer data packet cosstecy process lke the fgure fve, Practcal applcato, to acheve the followg: User beg cosstecy Beg cosstecy Cosstecy module Create sapshot Create success Volume copy servce Stop packet trasfer Stop success Packet trasmsso mudule Cosstecy success Cosstecy Destroy sapshot Destroy success Beg packet trasfer Beg success Fg 5: cosstecy Arraged raw data collecto ad backup data collecto to a progresso, accordace wth the data offset at the volume Make the data both the two aggregate to a bjectve mappg accordace wth the data offset o the dsk Dvded each aggregate order data to 512 Byte, costtute the aggregate D 1,D 2, D whch s subaggragate of D, D 1 ',D 2 ', D ' whch s subaggragate of D' Use fucto f(x) to calculate each aggregate summary value Compare summary value obta a result of data cosstecy 7 Coclusos Ths paper troduces a parallel trasmsso remote backup system The system ca backup local dsk data remote server Whe data loss occurs ths system ca recover data from remote server mmedately Ths system used parallel trasmsso to ehace sychrozato speed, ad make sure the data betwee local dsk ad remote dsk s cosstece 8 Refereces [1] LAWLER C M, SZYGENDA S A, THORNTON M A Techques for dsaster tolerat formato techology systems Proceedgs of the 1st Aual 2007 IEEE Systems Coferece[C] Hoolulu, HI, Uted States, 2007 333-338 [2] Lloyd S J, Joa P, Ja L, A Ecoomc ad Effcet Soluto for Real-tme Ole Remote Iformato 289
Backup, Joural of base Maagemet, 2003, 14(3): 56-73 [3] M J, A Vetch, J Wlkes Seeca, Remote Mrrorg Doe Wrte Proceedgs of the 2003 USENIX Techcal Coferece Sa Atoo, TX, USA, Jue, 2003:254-258 [4] R Cegela Selectg techology for dsaster recovery Proc of the Iteratoal Coferece o Depedablty of Computer Systems 2006:160-167 [5] Peter M Che, Edward K Lee, Garth A Gbso, Rady H Katz, Davd A Patterso, RAID: hghperformace, relable secodary storage, ACM Computg Surveys (CSUR), v26 2, p145-185, Jue 1994 [6] Adrew Trdgell, The rsyc algorthm[r] Caberra,The Australa Natoal Uversty,1996 [7] Shakh F,Shva Z Sapshot servce terface (ss), a geerc sapshot asssted backup framework for lux, teratoal coferece o dgtal formato maagemet, Bagalore, Ida, December 6-8,2006USA:EEE Computer Socety Press,2006:228 290