Abstract: Methods, apparatus and computer programs are provided for multiplication-free identification of the impulse response of an oversampled data channel. An input comprising a pseudo-random binary sequence of L symbols is supplied to the channel at a symbol rate of 1/T. A channel output is produced by sampling a channel output signal corresponding to the input with a sampling interval TS=(q/p)T, where q and p are relative prime integers with q<p, and q and L are relative prime integers. p polyphase sequences are produced from the channel output by selecting, for each polyphase sequence, every pth sample of the channel output, with a phase shift of one sample between successive polyphase sequences). A decimated binary sequence is produced by selecting every qth symbol of the channel input. Each polyphase sequence is correlated with the decimated binary sequence, the two possible binary values being of equal magnitude and opposite sign for the correlation.

Abstract: Access to encrypted data on a removable computer media such as a computer tape is controlled via a uniquely-structured header on the medium having a symmetrical key wrapped by asymmetrical encryption plus a public key associated with the asymmetrical encryption. The data on the medium is encrypted using the symmetrical key. Prior to automated reading of the data by a reader, a challenge is issued to a host system including the public key and preferably a nonce value. The host responds by signing the nonce using a private key associated with the public key in order to prove it has rights to decrypt the data. The symmetrical key is unwrapped using the private key, and finally the unwrapped symmetrical key is used to decrypt the data on the medium, thereby allowing automated reading of the tape data without the need or risk of two administrators sharing a symmetrical key value.

Abstract: An error correction code system, e.g. of a magnetic tape drive, applies error correction redundancy to data, separates it, or interleaves it, and records it into separate groups. An error correction encoder applies an outer error correction code to one of the separate groups of information, forming one set of rows of information and outer ECC information. An error correction encoder applies an outer error correction code to another separate group of information, forming another set of rows of information and outer ECC information. A data organizer interleaves the one set of rows of information and outer ECC information with the another set of rows of information and outer ECC information for recording on tracks of a recording media in an interleaved pattern of one set of rows of information and outer ECC information with another set of rows of information and outer ECC information.

Abstract: A read channel equalizer of a magnetic tape drive which equalizes digitally sampled magnetic signals detected by a read head is dynamically adapted. A detector of equalizer dynamic adaptation logic compares equalizer output signals to desired values that are based on the decoding scheme (such as +2, 0 and ?2 for PR4) to sense equalizer output signals that are offset from at least one desired value, and signals the fact of each offset and it polarity as amplitude independent error signals. The signaled sensed amplitude independent error signals are fed back to adjustable taps of the equalizer. The simplified error signals thus avoid complex calculations of waveform errors, such as least mean square calculations. The error signals may be weighted and may be adjusted to align synchronously provided error signals with asynchronous taps of the equalizer.

Abstract: Provided are a method, system, and article of manufacture in which a non-reversible signature of a symmetric cryptographic key is computed, wherein the symmetric cryptographic key is used to symmetrically encrypt data at rest in a storage device. The non-reversible signature is stored in association with the symmetrically encrypted data at rest in the storage device. The non-reversible signature is used to determine validity of a cryptographic key provided by a host for accessing the symmetrically encrypted data at rest in the storage device.

Abstract: Provided are techniques for copying data. Encrypted data from a first data storage medium is identified. A raw read of encrypted data from the first data storage medium is performed without decrypting the encrypted data. A raw write of the encrypted data to a second data storage medium is performed without again encrypting the encrypted data.

Abstract: Provided are a method, system, and article of manufacture for rekeying encryption keys for removable storage media. A rekey request is received for a coupled removable storage media, wherein encryption on the coupled removable storage media uses a first key and wherein the rekey request indicates a second key. The first key and the second key are accessed in response to the rekey request. The first key is used to perform decryption for the coupled removable storage media and the second key is used to perform encryption for the coupled removable storage media.

Abstract: Provided are a method, system, and article of manufacture for configuring a storage drive to communicate with encryption and key managers. A storage drive receives a request to access a coupled removable storage media for drive operations. The storage drive obtains encryption status for the coupled removable storage media from an encryption manager. The storage drive determines from the obtained encryption status whether to encrypt the coupled removable storage media to access. The storage drive obtains at least one key from a key manager in response to determining to encrypt with respect to the coupled removable storage media. The storage drive performs data operations using the at least one key to encrypt data.

Abstract: Provided are techniques for key generation and retrieval. Unique identifiers of two or more key servers are stored, wherein each key server is capable of generating keys for encryption of data and of returning keys for decryption of data. A key request is received. A technique for selecting one of the key servers to which the key request is to be forwarded is identified. One of the key servers is selected using the identified technique. The key request is sent to the identified key server.

Abstract: Provided are techniques for filling a drive table. A key request including at least one of a drive serial number and a world wide node name is received from a data storage drive. It is determined whether the drive serial number or a world wide node name are in an entry in a drive table. In response to determining that the drive serial number or a world wide node name are not in an entry in a drive table, a new entry is automatically added in the drive table that includes the at least one of a drive serial number and a world wide node name.

Abstract: Provided are techniques for determining whether to encrypt data. It is determined whether an element is to be encrypted based on an encryption policy, wherein the element comprises one of metadata and a data set. In response to determining that the element is to be encrypted, the element is encrypted and written to a data storage medium. In response to determining that the element is not to be encrypted, the element is written in the effective clear to the data storage medium.

Abstract: Provided are a method, system, and article of manufacture recovering remnant encrypted data on a removable storage media. An end of data (EOD) marker is detected on a removable storage media, wherein a first encryption key is associated with data preceding the EOD marker. Following the EOD marker, an identifier of a second encryption key associated with data following the EOD marker is read in response to detecting the EOD marker. The identifier is used to access the second encryption key and the second encryption key is used to decrypt the data following the EOD marker.

Abstract: A read channel equalizer of a magnetic tape drive which equalizes digitally sampled magnetic signals detected by a read head is dynamically adapted. A detector of equalizer dynamic adaptation logic compares equalizer output signals to desired values that are based on the decoding scheme (such as +2, 0 and ?2 for PR4) to sense equalizer output signals that are offset from at least one desired value, and signals the fact of each offset and its polarity as amplitude independent error signals. The signaled sensed amplitude independent error signals are fed back to adjustable taps of the equalizer. The simplified error signals thus avoid complex calculations of waveform errors, such as least mean square calculations. The error signals may be weighted and may be adjusted to align synchronously provided error signals with asynchronous taps of the equalizer.

Abstract: Data of a transaction to be synchronized is stored to a non-volatile store, and a Command Complete response is provided. Data of the transaction is supplied to a tape drive for writing to a magnetic tape. The storing, responding, and supplying operations are repeated for subsequent transactions. A Deferred Synchronize Command, specifying a previously supplied transaction, is provided to the tape drive, for writing data of the specified transaction. The tape drive, subsequent to writing all the data of the previously supplied transaction to magnetic tape, provides a Tape Command Complete, whereupon the data of the previously supplied transaction stored to the non-volatile store may be overwritten.

Abstract: Provided are a method, system, and program for writing data in a tape medium having wraps. A layout of the tape is provided including at least one segment within a full available length of a first set of wraps for writing user data and at least one segment within a full length of a second set of wraps for writing a work copy of the user data. User data is received to write to the tape medium and detecting is performed as to whether the data being written is occurring in a specified write mode. If the data writing is not occurring in the specified write mode, then writing the received user data to one segment in the first set of wraps. If the data writing is occurring in the specified write mode, then writing a work copy to available full length wraps not having user data.

Abstract: A cartridge handling system and method initialize a data storage cartridge having rewritable media for tamper resistant write once recording. A write once flag is written to a lockable section of a cartridge memory; the lockable section is locked to read-only; and a write once flag is written to a required data set of the rewritable media. Thus, write once flags are provided both at the locked read-only section of the cartridge memory, and at the required data set of the rewritable media.

Abstract: Provided are a method, system and article of manufacture for writing on a storage media. Data is received from a host. A determination is made whether the received data can potentially form a trailer record on the storage media. If the received data does not potentially form the trailer record, then the received data is written to the storage media.

Abstract: Provided are a method, system, and program for encoding data onto a storage medium. Host data is received and a plurality of device blocks are generated to include the host data. A directory is generated including entries for physical locations on the storage medium, wherein each entry identifies one device block at the physical location corresponding to the entry, and wherein the directory is used to access data on the storage medium. The directory entries are encoded in the device blocks written to the storage medium.

Abstract: A recording system of a magnetic tape drive is operated to cause one separate set of write heads to write data discontinuously to magnetic tape as received, and to save the data, and, during the same operation, to cause another separate set of write heads to rewrite data to magnetic tape in a continuous arrangement. The writing may be in parallel and simultaneous. Thus, during the same operation, and at the same time, the separate sets of the plurality of write heads, temporarily write the received data to magnetic tape so that the sender can erase its copy, and rewrite the saved data to the magnetic tape in a permanent arrangement, without waiting to complete first writing received data, to complete subsequently rewriting the data, and repeating.

Abstract: Provided is a method, system, and program for providing synchronization in a binary data stream. A binary data stream is received. A synchronization mark having at least one isolated peak is generated into at least one point in the data stream. An encoded data stream is formed by concatenating the synchronization mark with the received binary data. During decoding, the synchronization mark is detected based on error propagation occurring adjacent to the at least one isolated peak of the synchronization mark.