Correcting and eleting codes non-alignment data-updating method in distributed storage
阅读说明：本技术 分布式存储中纠删码非对齐数据更新方法 (Correcting and eleting codes non-alignment data-updating method in distributed storage ) 是由 董小社 李征 张兴军 王宇菲 于 2019-07-29 设计创作，主要内容包括：本发明公开了一种分布式存储中纠删码非对齐数据更新方法,在保证数据容错一致性以及数据可恢复的前提下,可实现纠删码数据的基本更新,并可实现纠删码数据的非对齐增量更新,接收用户发出的数据D<Sub>0</Sub>的更新,将纠删码数据块数据直接更新在原有数据块上,将数据D<Sub>0</Sub>更新所产生的纠删码校验块数据的更新以校验块数据更新增量Δ<Sub>0</Sub>的形式直接追加到校验块数据之后的预留空间中,对于纠删码数据更新时数据块的非对齐部分,将非对齐部分的数据块D’直接追加在原始数据块之后,并将非对齐部分按特定编码系数编码追加到所更新的校验块之后,以实现纠删码的非对齐数据更新。本发明所解决的是分布式存储中纠删码大规模使用的瓶颈之一。(The invention discloses correcting and eleting codes non-alignment data-updating methods in a kind of distributed storage, under the premise of guaranteeing data fault-tolerant consistency and recoverable data, the basic update of correcting and eleting codes data can be achieved, and can realize the non-alignment incremental update of correcting and eleting codes data, receive the data D that user issues 0 Update, correcting and eleting codes data block data is directly updated on legacy data block, by data D 0 The update of correcting and eleting codes check block data caused by updating updates increment Delta with check block data 0 Form be directly appended in the reserved space after check block data, the non-alignment part of data block when being updated for correcting and eleting codes data, the data block D ' of non-alignment part is directly added after original data block, and after non-alignment part is appended to updated check block by specific coding coefficient coding, to realize that the non-alignment data of correcting and eleting codes update.Solved by the invention is one of the bottleneck of correcting and eleting codes large-scale use in distributed storage.)
1. correcting and eleting codes non-alignment data-updating method in distributed storage, which comprises the following steps:
S1, host node will be with initial data D according to the size of correcting and eleting codes band piecemeal in distributed storage cluster0Corresponding part Phead+ΔPheadData to be updated to Ptail- Δ Ptail carry out equivalent cutting, obtain data segment 1, and according to S2~S4 into Row updates；By Δ PheadIt is updated with the part Δ Ptail according to step S5, Δ PheadData segment 2 is denoted as with the part Δ Ptail；
Wherein, PheadThe start bit of former correcting and eleting codes band, P are corresponded to for data D ' to be updatedtailIt is corresponded to for data D ' to be updated The stop bit of former correcting and eleting codes band；ΔPheadFor data D ' to be updated and initial data D0Start bit difference, Δ PtailFor to more New data D ' and initial data D0Stop bit difference；
S2, for data segment 1, host node cuts data to be updated progress equivalent according to the size of original correcting and eleting codes band piecemeal Point, and according to the start bit of data D ' to be updated memory node position corresponding with data block after stop bit calculating cutting, it will cut Data block after point is sent to each memory node on corresponding position；
S3 reads corresponding with data block to be updated original data block to memory on each memory node to be updated, calculating to The increment value Δ chunk of more new data block and original data block；According to former correcting and eleting codes encoder matrix coefficient, by each increment value Δ Chunk coding is sent to correcting and eleting codes check block memory node, adds after writing related correcting and eleting codes check block, finally sends rule Terminate ACK to host node；
S4, host node receive all increment value Δ chunk after correcting and eleting codes check block memory node rule terminates ACK, send Signal gives each data block node to be updated, and original data block is replaced with updated new data block by data block node to be updated； To all data blocks more new node feedback ACK to host node, host node updates the tail pointer of check block；
S5, for data segment 2, when 2 length of data segment is less than a stripe size, by Δ PheadWith Δ PtailCorresponding data The additional start bit P for writing data D ' to be updatedheadRule is carried out on memory node corresponding with stop bit Ptail, simultaneously will Δ P in data D ' to be updatedheadWith Δ PtailPartial data are saved by corresponding check block storage is sent to after hereafter rule encoding The additional rule of point terminates to return ACK to host node；
When 2 length of data segment is greater than a stripe size, the data of non-alignment part are subjected to cutting according to stripe size, it will The band block size data that can be syncopated as calculates complete band by correcting and eleting codes encoder matrix, is sent to corresponding node It is stored；Simultaneously by Δ P in data D ' to be updatedheadWith Δ PtailThe data supplementing of insufficient stripe size part is write to more The start bit P of new data D 'headWith stop bit PtailRule is carried out on corresponding memory node, to Δ in data D ' to be updated PheadWith Δ PtailThe data of insufficient stripe size part are encoded using code coefficient 1 in the domain Galois and are sent to opposite The additional rule of the check block memory node answered, finally returns to ACK to host node；
S6 to the end of host node receives all rules after ACK, sends tail pointer more newer command to all more new nodes, respectively more After new node receives tail pointer more newer command, the metadata of each data block and check block is first updated, then updates each data block and school The tail pointer of block is tested to latest position, to the end of tail pointer updates, host node more new metadata, non-alignment data update is finished.
2. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 1, which is characterized in that S5 In, by Δ P in data D ' to be updatedheadWith Δ PtailIt is additional that partial data are sent to associated check block memory node When rule:
As Δ P in data D ' to be updatedheadWith Δ PtailCorresponding only one check block of check block memory node of partial data When node, by Δ P in data D ' to be updatedheadWith Δ PtailPartial data are sent to the corresponding storage of check block first section The additional rule of point；
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block memory node of partial data has at least two verifications When block node, by Δ P in data D ' to be updatedheadWith Δ PtailPartial data are sent to corresponding check block any two Memory node adds rule.
3. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 1, which is characterized in that S5 In, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part use code coefficient 1 in the domain Galois When being encoded and being sent to corresponding check block memory node addition rule:
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block memory node of the data of insufficient stripe size part is only When having a check block node, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part use Code coefficient 1 is encoded and is sent to the additional rule of corresponding the first memory node of check block in the domain Galois；
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block memory node of the data of insufficient stripe size part has When at least two check block nodes, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part use Code coefficient 1 is encoded and is sent to the additional rule of corresponding check block any two memory node in the domain Galois.
4. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 1, which is characterized in that also wrap Include following steps:
S0.1, in distributed storage cluster host node receive that client sends to initial data D0Update request, according to client End data updates request instruction for initial data D0Corresponding correcting and eleting codes band is read in the memory of each memory node, host node Record initial data D0Initial position and length；
S0.2, client send data D ' to be updated and arrive host node, and host node is according to the start bit offset of data D ' to be updated The start bit P that data D ' to be updated corresponds to former correcting and eleting codes band is calculated with length gaugeheadWith stop bit Ptail；
S0.3, host node data D ' more to be updated and initial data D0Data offset and data length, calculate separately out to More new data D ' and initial data D0Start bit difference DELTA PheadWith stop bit difference DELTA Ptail；
S0.4, according to Δ PheadWith Δ PtailJudge whether it is the update of non-alignment data, updates, then carry out if non-alignment data S1~S6.
5. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 4, which is characterized in that if Δ PheadWith Δ PtailIt is equal to 0, then it represents that data D ' to be updated and initial data D0Start bit is mutually aligned with final value position, then originally It is secondary be updated to can align data update.
6. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 4, which is characterized in that if Δ PheadWith Δ PtailAny one of be not equal to 0, indicate data D ' to be updated compared to initial data D0In the presence of the amount of increasing, then this It is secondary to be updated to the update of non-alignment data.
7. correcting and eleting codes non-alignment data-updating method in distributed storage according to claim 1, which is characterized in that work as S6 After, host node, which sends to update, finishes signal ACK to client, and whole updating process finishes.
Technical field
The invention belongs to field of distributed storage, more particularly to one kind of distributed correcting and eleting codes storage system is non-right Neat correcting and eleting codes data-updating method.
Background technique
Replication policy and correcting and eleting codes are two kinds of common data redundancy techniques of field of distributed storage.Compared to copy plan Slightly, correcting and eleting codes have higher disk utilization.Such as Reed-Solomon code is a kind of common correcting and eleting codes.More replication policies Data are stored into multiple copies (usually three copies, such as HDFS), when some copy is lost, other copies can be passed through It copies back into and, however the space utilization rate of three copies is 1/3.
Correcting and eleting codes technology mainly passes through correcting and eleting codes algorithm and is encoded to obtain redundancy for original data, and by data and Redundancy stores together, fault-tolerant to achieve the purpose that.Its basic thought is that the original data element of n block is passed through erasure code Matrix calculates, and obtains m block redundant elements (check block), wherein being collectively referred to as item by the collection that n data block and m check block form Band.It, can be with when any of them m block element malfunctions (including initial data and redundant data) for the element of this n+m block Original n block number evidence is recovered by corresponding restructing algorithm.The process for generating verification, which is referred to as, encodes (encoding), restores The process for losing data block, which is referred to as, decodes (decoding).Disk utilization is n/ (n+m).Method based on correcting and eleting codes and more Copy method becomes a big mainstream of distributed memory system compared to having many advantages, such as that redundancy is low, disk utilization is high.
However existing distributed correcting and eleting codes storage compared to three copy storages there are many problems, wherein data of correcting and eleting codes Updating inflexible is a big main problem.It mainly has following reason: correcting and eleting codes data are needed when coding generates check block Initial data data are subjected to cutting according to data block size fixed in band, then could use corresponding encoder matrix pair The data block segmented carries out coding and generates check block.The data block and verification of these stringent cuttings in distributed memory system Block can be respectively stored in muti-piece disk or even more machines, become dispersion and discontinuous, data update be often related to be Data in system on more machines update.In addition, correcting and eleting codes check block is needed while updating when carrying out correcting and eleting codes data and updating, To guarantee the fault-tolerant consistency of data.Therefore the data at present on correcting and eleting codes update relatively difficult, and strictly regulating is needed to update The size of data block, it is extremely not flexible, and there is no effective way to solve the non-alignment data on correcting and eleting codes at present and update.
Summary of the invention
It is inflexible for haveing the defects that data update in existing distributed correcting and eleting codes storage, it is an object of the invention to It is proposed correcting and eleting codes non-alignment data-updating method in a kind of distributed storage, the present invention is directed to distributed correcting and eleting codes storage system Non-alignment data update, and the random length flexible data that can be realized on correcting and eleting codes updates, and does not have to be limited to correcting and eleting codes number Disperse discontinuous brought problem with data multinode according to the alignment of specific block size is pressed, while ensure that correcting and eleting codes data are being held Consistency in mistake, to solve the problems, such as that data update difficult and inflexible in distributed correcting and eleting codes storage system, make to be distributed Formula correcting and eleting codes storage system can accomplish that flexibly arbitrary data update.
To achieve the above object, the present invention adopts the following technical scheme:
Correcting and eleting codes non-alignment data-updating method in distributed storage, comprising the following steps:
S1, host node will be with initial data D according to the size of correcting and eleting codes band piecemeal in distributed storage cluster0It is corresponding Part Phead+ΔPheadData to be updated to Ptail- Δ Ptail carry out equivalent cutting, obtain data segment 1, and according to S2~ S4 is updated, by Δ PheadIt is updated with the part Δ Ptail according to step S5, Δ PheadData are denoted as with the part Δ Ptail Section 2；
Wherein, PheadThe start bit of former correcting and eleting codes band, P are corresponded to for data D ' to be updatedtailIt is right for data D ' to be updated The stop bit of former correcting and eleting codes band should be arrived；ΔPheadFor data D ' to be updated and initial data D0Start bit difference, Δ PtailFor Data D ' to be updated and initial data D0Stop bit difference；
S2, for data segment 1, data to be updated are carried out equivalent according to the size of original correcting and eleting codes band piecemeal by host node Cutting, and according to the start bit of data D ' to be updated memory node position corresponding with data block after stop bit calculating cutting, it will Data block after cutting is sent to each memory node on corresponding position；
S3 reads original data block corresponding with data block to be updated to memory, meter on each memory node to be updated Calculate the increment value Δ chunk of data block to be updated and original data block；According to former correcting and eleting codes encoder matrix coefficient, by each incremental value Δ chunk coding is sent to correcting and eleting codes check block memory node, adds after writing related correcting and eleting codes check block, finally sends and falls Disk terminates ACK to host node；
S4, host node receive all increment value Δ chunk after correcting and eleting codes check block memory node rule terminates ACK, Each data block node to be updated is sent a signal to, original data block is replaced with updated new data by data block node to be updated Block；To all data blocks more new node feedback ACK to host node, host node updates the tail pointer of check block；
S5, for data segment 2, when 2 length of data segment is less than a stripe size, by Δ PheadWith Δ PtailIt is corresponding Data supplementing writes the start bit P of data D ' to be updatedheadRule is carried out on memory node corresponding with stop bit Ptail, together When by Δ P in data D ' to be updatedheadWith Δ PtailPartial data are sent to the additional rule of corresponding check block memory node, Terminating return affairs terminates to reply message ACK to host node；
When 2 length of data segment is greater than a stripe size, the data of non-alignment part are cut according to stripe size Point, the band block size data that will be syncopated as calculates complete band by correcting and eleting codes encoder matrix, is sent to corresponding Node stored；Simultaneously by Δ P in data D ' to be updatedheadWith Δ PtailThe data supplementing of insufficient stripe size part is write To the start bit P of data D ' to be updatedheadWith stop bit PtailRule is carried out on corresponding memory node, to data D ' to be updated Middle Δ PheadWith Δ PtailThe data of insufficient stripe size part are encoded and are sent to using code coefficient 1 in the domain Galois The additional rule of corresponding check block memory node, finally returns to ACK to host node；
S6 to the end of host node receives all rules after ACK, sends tail pointer more newer command to all more new nodes, After each more new node receives tail pointer more newer command, the metadata of each data block and check block is first updated, then update each data block Tail pointer with check block is to latest position, and to the end of tail pointer updates, host node more new metadata, non-alignment data have updated Finish.
In S5, by Δ P in data D ' to be updatedheadWith Δ PtailPartial data are sent to associated check block and deposit When storage node adds rule:
As Δ P in data D ' to be updatedheadWith Δ PtailCorresponding only one school of check block memory node of partial data When testing block node, by Δ P in data D ' to be updatedheadWith Δ PtailPartial data are sent to corresponding check block first and deposit Store up the additional rule of node；
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block memory node of partial data has at least two When check block node, by Δ P in data D ' to be updatedheadWith Δ PtailIt is any that partial data are sent to corresponding check block The additional rule of two memory nodes.
In S5, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part use the domain Galois When middle code coefficient 1 is encoded and is sent to corresponding check block memory node addition rule:
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block storage section of the data of insufficient stripe size part When only one check block node of point, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part make It is encoded with code coefficient 1 in the domain Galois and is sent to the additional rule of corresponding the first memory node of check block；
As Δ P in data D ' to be updatedheadWith Δ PtailThe corresponding check block storage section of the data of insufficient stripe size part When point has at least two check block nodes, by Δ P in data D ' to be updatedheadWith Δ PtailThe data of insufficient stripe size part It is encoded using code coefficient 1 in the domain Galois and is sent to corresponding check block any two memory node addition and fallen Disk.
Further include following steps:
S0.1, in distributed storage cluster host node receive that client sends to initial data D0Update request, root Request instruction is updated by initial data D according to client data0Corresponding correcting and eleting codes band is read in the memory of each memory node, Host node records initial data D0Initial position and length；
S0.2, client send data D ' to be updated and arrive host node, and host node is inclined according to the start bit of data D ' to be updated Shifting amount and length gauge calculate the start bit P that data D ' to be updated corresponds to former correcting and eleting codes bandheadWith stop bit Ptail；
S0.3, host node data D ' more to be updated and initial data D0Data offset and data length, count respectively Calculate data D ' to be updated and initial data D0Start bit difference DELTA PheadWith stop bit difference DELTA Ptail；
S0.4, according to Δ PheadWith Δ PtailJudge whether it is the update of non-alignment data, is updated if non-alignment data, then Carry out S1~S6.
If Δ PheadWith Δ PtailIt is equal to 0, then it represents that data D ' to be updated and initial data D0Start bit and final value position phase Mutually alignment, then this be updated to can align data update.
If Δ PheadWith Δ PtailAny one of be not equal to 0, indicate data D ' to be updated compared to initial data D0In the presence of The amount of increasing then this time is updated to the update of non-alignment data.
After S6, host node, which sends to update, finishes signal ACK to client, and whole updating process finishes.
Compared with prior art, the invention has the following beneficial effects:
Correcting and eleting codes non-alignment data-updating method is guaranteeing the efficient space utilization of correcting and eleting codes in distributed storage of the present invention Under rate and fault-tolerant energy, by being split judgement to the update of non-alignment data, the spy of different piece is updated according to non-alignment data Sign uses different coding modes and different storage strategies, and distribution can be realized in the case where guaranteeing data consistency The non-alignment data of correcting and eleting codes update in storage.The present invention is first by updating specific feelings to correcting and eleting codes data in distributed system The judgement of condition with code coefficient 1 in the domain Galois encodes different piece using based on original encoder matrix, improves point The coding of correcting and eleting codes data and update efficiency in cloth storage.Secondly by the different piece updated to non-alignment data using not Same storage strategy is stored respectively, and the non-alignment data of correcting and eleting codes are updated to the memory node being closely related therewith, makes to entangle and delete Code data update the constraint being no longer aligned by across the failure domain dispersion of correcting and eleting codes data with block, can accomplish random length, any position The data set update.The present invention in distributed storage correcting and eleting codes non-alignment data update in less than a strip portion use with The fault-tolerant consistency that space utilization rate guarantees distributed storage can be improved in the strategy of machine storage.Finally, used in the present invention It receives all node updates and finishes after signal that the mode of more New Data Segment tail pointer can be very good to guarantee that data are not lost again, tie up The fault-tolerant consistency and sky of data block and check block data when holding the atomicity of affairs, while the storage of correcting and eleting codes data will not be destroyed Between utilization rate.In conclusion the present invention can be realized the update of the random length flexible data on correcting and eleting codes, and do not have to be limited to entangle Yard data are deleted by the alignment of specific block size and the discontinuous brought problem of data multinode dispersion, while ensure that correcting and eleting codes number According to the consistency on fault-tolerant, thus solve the problems, such as that data update difficult and inflexible in distributed correcting and eleting codes storage system, Distributed correcting and eleting codes storage system is set to accomplish that flexibly arbitrary data update.
Detailed description of the invention
Fig. 1 is correcting and eleting codes non-alignment data-updating method overall flow figure in distributed storage of the present invention.
Fig. 2 is common correcting and eleting codes architecture diagram in prior art distributed memory system, and wherein correcting and eleting codes data can be drawn It is divided into different data blocks and is organized into different bands, each band runs through all data block node and check block node, And item takes each piece and is stored on different nodes according to the setting of the failure domain of distributed memory system.
Fig. 3 is to be determined as that the data of non-alignment update control schematic diagram in the present invention, wherein data to be updated and original number According to having different offset and length, data to be updated in this way can not be snapped in initial data.
Fig. 4 is the decision principle flow diagram of non-alignment partial data check block code coefficient of the present invention.
Specific embodiment
Purpose, scheme, technical detail and specific embodiment to illustrate the invention, below in conjunction with attached drawing to the present invention into Row is further to be described in detail.
Referring to Fig.1, correcting and eleting codes non-alignment data-updating method in distributed storage of the present invention, comprising the following steps:
(1) in distributed storage cluster host node receive client send to initial data D0Update request, according to It requests initial data D0Corresponding correcting and eleting codes band is read in the memory of each memory node, wherein record initial data D0's Initial position and length (offset+length).
(2) client sends data D ' to be updated and arrives host node, and host node is deviated according to the start bit of data D ' to be updated Amount calculates the start bit P that data D ' to be updated corresponds to former correcting and eleting codes band with length (offset+length)headWith termination Position Ptail。
(3) host node data D ' more to be updated and initial data D0Data offset and data length, calculate separately Data D ' to be updated and initial data D out0Start bit difference DELTA PheadWith stop bit difference DELTA Ptail。
(4) if Δ PheadWith Δ PtailIt is equal to 0, indicates data D ' to be updated and initial data D0Start bit and final value position Be mutually aligned, then this be updated to can align data update；If Δ PheadWith Δ PtailAny one of be not equal to 0, indicate to more New data D ' compares initial data D0In the presence of the amount of increasing, then the update of non-alignment data is this time updated to.
(5) the non-alignment data to be carried out are updated, host node is according to correcting and eleting codes band point in distributed storage cluster The size of block will part (P corresponding with initial datahead+ΔPheadTo Ptail-ΔPtail) data to be updated carry out equivalent cut Point, and (6)~step (8) is updated as steps described below, the Δ P that will be syncopated asheadWith Δ PtailPart is according to step (10) ~step (13) is updated.
(6) P for being syncopated ashead+ΔPheadTo Ptail-ΔPtailPartial data, host node is according to original correcting and eleting codes item Size with piecemeal is by alignment of data to be updated to initial data D0On, and treated according to the dicing position of correcting and eleting codes data block More new data D ' carries out equivalent cutting.Finally according to data block pair after the start bit of data D ' to be updated and stop bit calculating cutting The memory node position answered sends the data block after alignment cutting on corresponding each memory node, is stored temporarily in interior In depositing.
(7) on each memory node to be updated, original data block corresponding with data block to be updated is read to memory, meter Calculate increment value Δ the chunk=chunk_D '-chunk_D of data block to be updated Yu each piece of original data block0.It is entangled according to original A yard encoder matrix is deleted, sends correcting and eleting codes check block for each Δ chunk*Aij (Aij is corresponding coefficient in encoder matrix) respectively Memory node and addition are write after associated correcting and eleting codes check block.Pending data rule terminates, and sends successful information ACK to main section Point indicates rule success.
(8) host node receives all Δ Chunk after correcting and eleting codes check block memory node rule terminates ACK, sends letter Number give all back end to be updated, on each node to be updated, original data block is replaced with update by each data block node New data block afterwards.After original data block being updated using new data block on all nodes to be updated, section to be updated ACK is to host node for point feedback success.
(9) when host node receives after being updated successfully signal ACK of all reality more new node institute feedback, host node issues letter The tail pointer of check block number is updated, update finishes.
The wherein update mode of above-mentioned two-period form can guarantee that data will not lose, while maintain the atomicity of affairs, When occurring unexpected in renewal process, host node not will be updated the data tail pointer of check block node, ensure that total system not Data can be lost because of the accident in renewal process or generation data are inconsistent.
10) the Δ P for being syncopated asheadJudged with the data length of the part Δ Ptail, if length is greater than a band When middle data segment, length, by Δ PheadCutting is carried out according to data segment, length in band with the data of the part Δ Ptail, for cutting The data segment, length data that meet separated encode according to original matrix, for be syncopated as less than a strip data segment length data by It is encoded according to code coefficient (i.e. code coefficient 1 in the domain Galois) specific in the domain Galois.
11) in Δ PheadWith the data for meeting strip data segment length being syncopated as on the part Δ Ptail, main section Point first obtains original encoding matrix, is one by one carried out the strip data segment length data being syncopated as than coding using original encoding matrix, Check block data are generated, data block data is sent to corresponding storage with check block data and connects node rule, rule terminates to return ACK is to host node, but not more new metadata.According to said method to it is all can original matrix coding data encode, send, fall Disk.
(12) in Δ PheadWith the insufficient strip data segment length data being syncopated as on the part Δ Ptail, first by Δ PheadData D ' start bit P to be updated is write with partial data addition on Δ PtailheadStorage corresponding with stop bit Ptail Rule is carried out on node, is finished and is returned to ACK to host node, but the not tail pointer of more New Data Segment.Simultaneously by data D ' to be updated Middle Δ PheadCoding is carried out with specific unit battle array with the data of the part Δ Ptail and is sent to associated check block any two Memory node (if only one check block node, defaulting the first memory node of check block) rule finishes and returns to ACK to main section Point, the equally not tail pointer of more New Data Segment.
(13) after host node, which receives all rules, finishes ACK, tail pointer more newer command is sent to all more new nodes, After each node receives tail pointer more newer command, the tail pointer for updating each data block and check block is newest position, band tail pointer Update terminates, host node more new metadata.The update of non-alignment data finishes.
(14) after update, host node, which sends to update, finishes signal ACK to client, and whole updating process finishes.