US6298425B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Computer disk management system using doublet A-B logging
Assignee: Hewlett Packard Enterprise Development LP
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Filing: 1999-01-12
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Granted: 2001-10-02
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Expires: 2019-01-12
Abstract
Abstract Updating a single block of metadata is optimized into a single I/O operation. Resilience against single block failure and system crashes with a single or less than three I/O operations is provided. The present invention method and apparatus stores two copies of the metadata in two areas on disk. Each individual block of metadata in each area is duplicated as a doublet. The doublet provides two copies of a subject block to be written to disk as a single I/O. This enables metadata to survive a single block failure since such a failure only affects half of the doublet. Further, each block of metadata has header information including an indication of transaction and a part count. A transaction is not deemed committed until corresponding blocks of all parts are found.
Inventors
- 👤 Christopher Whitaker
- 👤 Conor Morrison
- 👤 Alan Gordon Dewar
- 👤 James Hogg
- 👤 Kevin Playford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 06:13
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/07; G06F11/14; G06F11/1402; G06F11/1415; G06F11/1435; G06F11/1471; G06F11/16; G06F11/20; G06F11/2053; G06F11/2056; G06F11/2064; G06F11/2087; Y; Y10; Y10S; Y10S707/00; Y10S707/99951; Y10S707/99952; Y10S707/99953; Y10S707/99955
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
147 words
Computer memory apparatus for maintaining metadata, the metadata correlating a physical memory and a corresponding virtual memory to each other, the apparatus comprising: a first area of the physical memory storing blocks of metadata, for each block of metadata, the first area storing the block and a duplicate of the block of metadata; and a second area of the physical memory, the second area spaced apart from the first area of the physical memory, and for each block of metadata, the second area storing a copy of the block and a copy of the duplicate of the block of metadata, for each block of metadata, the block and the duplicate of the block in the first and second areas enabling the metadata to survive a single block failure of an underlying media of the physical memory during writing of the metadata to the first and second areas.
Claim 2
Dependent Claim
147 words
Computer memory apparatus for maintaining metadata, the metadata correlating a physical memory and a corresponding virtual memory to each other, the apparatus comprising: a first area of the physical memory storing blocks of metadata, for each block of metadata, the first area storing the block and a duplicate of the block of metadata; and a second area of the physical memory, the second area spaced apart from the first area of the physical memory, and for each block of metadata, the second area storing a copy of the block and a copy of the duplicate of the block of metadata, for each block of metadata, the block and the duplicate of the block in the first and second areas enabling the metadata to survive a single block failure of an underlying media of the physical memory during writing of the metadata to the first and second areas.
Claim 3
Dependent Claim
35 words
Apparatus as claimed in claim 1 further comprising: for each block of metadata, a header indicating (a) update transaction and (b) certain part in a plurality of parts of the transaction, of the metadata block.
Claim 4
Dependent Claim
30 words
Apparatus as claimed in claim 1 wherein the first and second areas of physical memory allow a single block of metadata to be updated in less than three I/O operations.
Claim 5
Dependent Claim
50 words
Apparatus as claimed in claim 3 further comprising update means for updating a block of metadata, the update means updating the block of metadata in one of the first area and the second area, by alternating between the first and second areas for each update of the block of metadata.
Claim 6
Dependent Claim
41 words
Apparatus as claimed in claim 4 wherein the update means provides rollback of a block of metadata, from the second area to the first area, if an I/O operation fails to complete updating the block of metadata in the first area.
Claim 7
Dependent Claim
41 words
Apparatus as claimed in claim 4 wherein the update means provides rollforward of a block of metadata from the first area to the second area, if an I/O operation fails to complete updating the block of metadata in the second area.
Claim 8
Dependent Claim
17 words
Apparatus as claimed in claim 1 wherein the physical memory and virtual memory form a snappy disk.
Claim 9
Dependent Claim
145 words
In a computer system having physical memory, corresponding virtual memory, and metadata for indicating correspondence between physical and virtual memory, a method of maintaining the metadata comprising the steps of: providing a first area in physical memory for storing metadata; providing a second area separate from the first area in the physical memory, for storing a copy of the metadata stored in the first area; for each block of metadata, (i) writing the block and a duplicate of the block in the first area, and (ii) copying in the second area, the block and the duplicate of the block from the first area, said writing of a block and respective duplicate, in each of the first and second areas, is performed in less than three I/O operations and in a manner that survives a single block failure of an underlying media of the physical memory.
Claim 10
Dependent Claim
145 words
In a computer system having physical memory, corresponding virtual memory, and metadata for indicating correspondence between physical and virtual memory, a method of maintaining the metadata comprising the steps of: providing a first area in physical memory for storing metadata; providing a second area separate from the first area in the physical memory, for storing a copy of the metadata stored in the first area; for each block of metadata, (i) writing the block and a duplicate of the block in the first area, and (ii) copying in the second area, the block and the duplicate of the block from the first area, said writing of a block and respective duplicate, in each of the first and second areas, is performed in less than three I/O operations and in a manner that survives a single block failure of an underlying media of the physical memory.
Claim 11
Dependent Claim
30 words
The method of claim 8 further comprising: for each block of metadata, providing an indication of (a) update transaction and (b) part in a plurality of parts of the transaction.
Claim 12
Dependent Claim
27 words
The method of claim 8 further comprising the step of using a single I/O operation, updating a block of metadata stored in the first and second areas.
Claim 13
Dependent Claim
30 words
The method of claim 10 wherein the step of updating a block of metadata includes alternating between the first and second areas, for each update of the block of metadata.
Claim 14
Dependent Claim
43 words
The method of claim 11 wherein the step of updating further includes rolling back the block of metadata from the second area to the first area, if an I/O operation fails to complete updating of the block of metadata in the first area.
Claim 15
Dependent Claim
42 words
The method of claim 11 wherein the step of updating further includes rolling forward the block of metadata from the first area to the second area, if an I/O operation fails to complete updating the block of metadata in the second area.
Claim 16
Dependent Claim
17 words
The method of claim 8 wherein the physical memory is formed of a plurality of storage units.
Claim 17
Dependent Claim
167 words
A computer disk system having (a) physical memory formed by a plurality of storage units, (b) corresponding virtual memory and (c) metadata for mapping between addresses of virtual memory and addresses of physical memory, the computer disk system comprising: maintenance means for maintaining metadata, the maintenance means including: (i) a first area of the physical memory for storing blocks of metadata, for each block of metadata, the first area storing the block and a duplicate of the block of metadata; and (ii) a second area of the physical memory, the second area spaced apart from the first area of the physical memory, and for each block of metadata, the second area storing a copy of the block and the duplicate of the block of metadata, for each block of metadata, the maintenance means storing the block and duplicate of the block, in the first and second areas, in a manner such that the metadata survives a single block failure of an underlying media of the physical memory.
Claim 18
Dependent Claim
167 words
A computer disk system having (a) physical memory formed by a plurality of storage units, (b) corresponding virtual memory and (c) metadata for mapping between addresses of virtual memory and addresses of physical memory, the computer disk system comprising: maintenance means for maintaining metadata, the maintenance means including: (i) a first area of the physical memory for storing blocks of metadata, for each block of metadata, the first area storing the block and a duplicate of the block of metadata; and (ii) a second area of the physical memory, the second area spaced apart from the first area of the physical memory, and for each block of metadata, the second area storing a copy of the block and the duplicate of the block of metadata, for each block of metadata, the maintenance means storing the block and duplicate of the block, in the first and second areas, in a manner such that the metadata survives a single block failure of an underlying media of the physical memory.
Claim 19
Dependent Claim
38 words
A computer disk system as claimed in claim 15 further comprising: for each block of metadata, a header indicating (a) update transaction and (b) certain part in a plurality of parts of the transaction, of the metadata block.
Claim 20
Dependent Claim
26 words
A computer disk system as claimed in claim 15 wherein said maintenance means updates a single block of metadata in a less than three I/O operations.
Claim 21
Dependent Claim
34 words
A computer disk system as claimed in claim 17 wherein said maintenance means updates a block of metadata by alternating between the first and second areas, for each update of the block of metadata.
Claim 22
Dependent Claim
43 words
The computer disk system as claimed in claim 18 wherein the maintenance means rolls back a block of metadata from the second area to the first area, upon an I/O operation failing to complete updating the block of metadata in the first area.
Claim 23
Dependent Claim
43 words
The computer disk system as claimed in claim 18 wherein the maintenance means rolls forward a block of metadata from the first area to the second area, upon an I/O operation failing to complete updating the block of metadata in the second area.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-10-01 | 2005-04-02 | 2005-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-10-01 | 2009-04-02 | 2009-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-10-01 | 2013-04-02 | 2013-10-02 | $7700.00 | Window Closed / Lapsed |