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Metadata services for the Parallax storage system Aggarwal, Gitika
Abstract
Parallax is a distributed storage system that uses virtualization to provide storage facilities specifically for virtual environments. In Parallax, fragmentation occurs when the block addresses visible to the guest virtual machine are sequentially placed, but the corresponding physical addresses are not. Because of the copy-on- write (CoW) nature of Parallax, as virtual disks are created, cloned, deleted, snapshotted and migrated, some fragmentation of the physical media can occur, potentially incurring seeks even when performing sequential accesses to the virtual disk. As the storage pool ages, performance issues due to unchecked fragmentation, unreclaimed storage space and duplicate data can cause significant concern. CoW snapshots also introduce sharing semantics between virtual disks and snapshots. The ability to create CoW clones of virtual disks from snapshots of other virtual disks leads to more sharing relationships. As a result block reclamation and allocation become non-trivial. We have developed utilities for garbage collecting, de-fragmenting free disk space and virtual disks and reclaiming duplicate read-only blocks in the storage pool managed by Parallax. They work by updating and maintaining the metadata structures related to each virtual disk and its snapshots. They use very coarse grained locking on the metadata and work at the block level. They operate across the storage pool and are agnostic to the operating systems and file systems used by the virtual machines.
Item Metadata
Title |
Metadata services for the Parallax storage system
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2008
|
Description |
Parallax is a distributed storage system that uses virtualization to provide storage
facilities specifically for virtual environments. In Parallax, fragmentation occurs
when the block addresses visible to the guest virtual machine are sequentially
placed, but the corresponding physical addresses are not. Because of the copy-on-
write (CoW) nature of Parallax, as virtual disks are created, cloned, deleted,
snapshotted and migrated, some fragmentation of the physical media can occur,
potentially incurring seeks even when performing sequential accesses to the virtual
disk. As the storage pool ages, performance issues due to unchecked fragmentation,
unreclaimed storage space and duplicate data can cause significant concern.
CoW snapshots also introduce sharing semantics between virtual disks and snapshots.
The ability to create CoW clones of virtual disks from snapshots of other
virtual disks leads to more sharing relationships. As a result block reclamation and
allocation become non-trivial.
We have developed utilities for garbage collecting, de-fragmenting free disk
space and virtual disks and reclaiming duplicate read-only blocks in the storage
pool managed by Parallax. They work by updating and maintaining the metadata
structures related to each virtual disk and its snapshots. They use very coarse
grained locking on the metadata and work at the block level. They operate across
the storage pool and are agnostic to the operating systems and file systems used by
the virtual machines.
|
Extent |
3058601 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-03-05
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0051577
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2008-11
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International