J. Metzner. A parity structure for large remotely located replicated data files. IEEE Transactions on Computers, 32(8):727-- 730, Aug. 1983.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....presented earlier, or by transmitting the entire item in the case of small database records. In the following, we discuss the problems arising in this scenario, with emphasis on a recent approach described in [26, 33, 46] Some earlier work on reconciliation of record based data appeared in [7, 1, 31, 32]. Consider the case, assumed in [46] of a handheld device using the Palm Hotsync program to synchronize its database of addresses or appointments with a desktop device. If the handheld was last synchronized with the same desktop, then the Palm Hotsync software can use auxiliary logging ....

J. Metzner. A parity structure for large remotely located replicated data files. IEEE Transactions on Computers, 32(8):727--730, August 1983.

....copy of a database held by host #. When the corruptions are non destructive, meaning that the corruptions only change data rather than adding new data or deleting old data, the problem of synchronizing the two databases is precisely the classical problem of error correction [22] Many sources [23 27] have addressed synchronization of such non destructively corrupted databases. A more recent work [28] makes a direct link to coding theory by using a well known class of good codes known as Reed Solomon codes to affect such synchronizations. However, the applications that we address in this work ....

J.J. Metzner, "A parity structure for large remotely located replicated data files," IEEE Transactions on Computers, vol. C-32, no. 8, pp. 727--730, August 1983.

....copy of a database held by host A. When the corruptions are non destructive, meaning that the corruptions only change data rather than adding new data or deleting old data, the problem of synchronizing the two databases is precisely the classical problem of error correction [22] Many sources [23 27] have addressed synchronization of such non destructively corrupted databases. A more recent work [28] makes a direct link to coding theory by using a well known class of good codes known as Reed Solomon codes to affect such synchronizations. However, the applications that we address in this work ....

J.J. Metzner, "A parity structure for large remotely located replicated data files," IEEE Transactions on Computers, vol. C-32, no. 8, pp. 727--730, August 1983.

....parallel algorithm with N # log 2 n comparisons for the 1 problem. Let page k be indexed by the binary N vector of the number k. Then the ith comparison consists of signatures of the set of pages with 1 in the ith bit. We call the set of comparisons the binary representation matrix (BRM) Metzner [3] proposed a sequential algorithm and later [4] improved it with two other sequential tree algorithms. In particular, for the 2 problem, the second algorithm in [4] is equivalent to a parallel algorithm consisting of BRM and a comparison on 0018 9340 97 10.00 1997 IEEE ....

J.J. Metzner, "A Parity Structure for Large Remotely Located Replicated Data Files," IEEE Trans. Computers, vol. 32, no. 8, pp. 727-730, Aug. 1983.

....S as a string consisting of the elements of S listed in lexicographic order. Insertions and deletions from S then correspond to insertions and deletions from the sorted string. Many methods have been proposed in the literature for both traditional error correction and spurious error correction [20, 21, 22, 23, 24, 25, 26, 27, 28]. In line with the former model, Metzner and Kapturowski [24] examined the problem of correcting disagreeing pages between two di erent versions of a le using a minimum communication complexity. They presented an algorithm that, with high probability, corrected most cases of up to disagreeing ....

J.J. Metzner, \A parity structure for large remotely located replicated data les," IEEE Transactions on Computers, vol. C-32, no. 8, pp. 727-730, August 1983.

....These protocols assume a fixed upper bound f on d(x; y) and they require the transmission of Omega Gamma f log n) bits for the Hamming distance. If d(x; y) f , then the protocols result in an error; if d(x; y) o(f) then we show in this paper that too many bits are transmitted. Metzner [Met83, Met91] Abdel Ghaffar and El Abbadi [AGE94] and Barbar a and Lipton [BL91] consider the concrete problem of identifying different pages between two copies of an updated file. It is assumed that the differences between pages are aligned with the page boundaries, effectively resulting in Hamming ....

....match. Note that there is no danger of false positives; if a test leads us to believe that the substrings are different, then there is zero probability that they actually match. The following scheme is a straightforward way to locate and correct differences, and is similar to that proposed in [Met83] Mapping our terminology onto that of the above problem, the locations of Hamming differences between the two strings are the distinguished characters. We shall use the proposed simple divide and conquer algorithm to locate them. The test we perform involves communication: in each round, one ....

J. J. Metzner. A parity structure for large remotely located replicated data files. IEEE Transactions on Computers, 32(8):727--730, August 1983.

....is assumed large, hence it is not cost effective if the entire file copies are transmitted among the sites. A known approach is to compute a page signature for each page copy, and transmit and compare the signatures instead. The page signature is typically much smaller than the page. For example [8] proposed to use a parity structure for the page signatures. Two pages with different page signatures are definitely not identical, but two pages that are different may happen to be translated into the same page signature. However the chance of this happening can be made small by making the ....

....P rob B that given 2 corrupted page copies with different error patterns, their page signatures are the same is also x. Since P rob C is negligible, P rob B is also negligible. Finally note that P rob A is comparable to acceptable values of P rob C . For example, for the algorithm given in [8], suppose each signature has c bits, if the parity rules are chosen at random and the replicated file copies differ in a random fashion, there would be a probability of 2 Gammac that two page copies with different contents have the same page signature, or P rob C = 1 2 c for this page ....

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Metzner, J.J. (1983) A parity structure for large remotely located replicated data files. IEEE Transactions on Computers. Aug 1983. C-32:727-730.

....is assumed large, hence it is not costeffective if the entire file copies are transmitted among the sites. A known approach is to to compute a page signature for each page copy, and transmit and compare the signatures instead. The page signature is typically much smaller than the page. For example [7] proposed to use a parity structure for the page signatures. Two pages with different page signatures are definitely not identical, but two pages that are different may happen to be translated into the same page signature. However the chance of this happening can be made small by making the ....

....rob B that given 2 corrupted page copies with different error patterns, their page signatures are the same is also x. Since P rob C is negligible, P rob B is also negligible. Finally we point out that P rob A is comparable to acceptable values of P rob C . For example, for the algorithm given in [7], suppose each signature has c bits, if the parity rules are chosen at random and the replicated file copies differ in a random fashion, there would be a probability of 2 Gammac that two page copies with different contents have the same page signature, or P rob C = 1 2 c for this page ....

[Article contains additional citation context not shown here]

J. Metzner. A parity structure for large remotely located replicated data files. IEEE Transactions on Computers, pages C--32:727--730, Aug 1983.

....in the M sites in order to determine the corrupted pages. We assume that secondary sites can only communicate with the primary site. Since the pages may be quite large, it is common to compute for each page P i a concise representation, called the page signature of P i , and denoted by p i [7]. Each page signature has length b bits, which is typically much less than the length of the page. Thus, two different pages may have the same page signature. Metzner [7] has developed a simple technique to assign signatures to pages using feedback shift registers. In this technique, it is ....

....large, it is common to compute for each page P i a concise representation, called the page signature of P i , and denoted by p i [7] Each page signature has length b bits, which is typically much less than the length of the page. Thus, two different pages may have the same page signature. Metzner [7] has developed a simple technique to assign signatures to pages using feedback shift registers. In this technique, it is assumed that the number of pages in the file, N , is less than the total number of page signatures 2 b , i.e. b log 2 N . This condition means that there are fewer bits ....

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J. J. Metzner, "A parity structure for large remotely located replicated data files," IEEE Trans. Comput., vol. C-32, pp. 727--730, Aug. 1983.

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J. Metzner. A parity structure for large remotely located replicated data files. IEEE Transactions on Computers, 32(8):727-- 730, Aug. 1983.

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