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Optimize un-aligned or smaller than sector size I/O requests on volumes hosted on disks with heterogeneous sector size.

IP.com Disclosure Number: IPCOM000240674D
Publication Date: 2015-Feb-17
Document File: 4 page(s) / 344K

Publishing Venue

The IP.com Prior Art Database

Related People

Apurv Barve: INVENTOR

Abstract

Select a mirror to read such that it optimizes I/O operation in case of un-aligned or smaller than sector size I/O's on a mirrored volume hosted on disks with heterogeneous sector size.

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Optimize un-aligned or smaller than sector size I/O requests on volumes hosted on disks with heterogeneous sector size.

Apurv Barve

Symantec Corporation

Abstract

Select a mirror to read such that it optimizes I/O operation in case of un-aligned or smaller than sector size I/O's on a mirrored volume hosted on disks with heterogeneous sector size.

Copyright © 2015 Symantec Corporation. All rights reserved.

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Copyright © 2015 Symantec Corporation. All rights reserved.


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Optimize un-aligned or smaller than sector size I/O requests on volumes hosted on disks with heterogeneous sector size.

Problem Statement

Sector size for a mirrored volume hosted on devices having heterogeneous sector size would be minimum of sector size of all disks within the volume. Un-aligned or smaller I/O's on such volumes would fail. To avoid failure of such I/O's, we require alignment of I/O to sector size of the device to which the I/O maps to in case of READS and Read Modify Write operation (RMW ) in case of WRITES. READ operation on a mirrored volume is satisfied by one of the plex which is chosen randomly or based on some READ policy set by the user.

When doing a WRITE operation on mirrored volume, WRITE request gets routed to all mirrors of the volume which will be subsequently routed through plex-subdisk-disk hierarchy. For WRITES which are smaller than sector size of any disk in the volume or un-aligned to sector size of some disk in volume an expensive Read-Modi...