Oracle ZFS Storage Appliance: How to avoid mis-alignment when using ZFS on LDOM clients
Last updated on JANUARY 05, 2018
Applies to:Oracle ZFS Storage ZS4-4 - Version All Versions to All Versions [Release All Releases]
Oracle ZFS Storage ZS3-2 - Version All Versions to All Versions [Release All Releases]
Sun ZFS Storage 7320 - Version All Versions to All Versions [Release All Releases]
Sun ZFS Storage 7420 - Version All Versions to All Versions [Release All Releases]
Sun ZFS Storage 7120 - Version All Versions to All Versions [Release All Releases]
7000 Appliance OS (Fishworks)
This document provides the steps required to ensure there is no mis-alignment when LDOMs use ZFS on top of ZFSSA LUNs.
The procedure overview is as follows :
- ZFSSA : Create a LUN with a volblocksize of 8KB (default)
- Control domain : Make the LUN recognized
- Control domain : Use format to configure a simple disk layout
- Control domain : Assign the c0txd0s2 partition to an LDOM
- LDOM : Login to the LDOM and list the disks via format
- LDOM : Retrieve the vdc instance of the device(s) you want to use for a ZFS pool
- LDOM : Edit the /platform/sun4v/kernel/drv/vdc.conf
- LDOM : Reboot the LDOM
- LDOM : Create the pool
- LDOM : Create a ZFS filesystem and confirm correct filesystem operation
Misalignment can be expensive in term of extra IOs done on the ZFSSA side. For more details, see http://blogs.oracle.com/dlutz/entry/partition_alignment_guidelines_for_unified.
Since Solaris 18.104.22.168.0, it becomes a little easier to remove mis-alignment issues when LDOMs use ZFS on top of LUNS exported by a ZFSSA.
The enhancement comes from : ER 15824910 - Add support to configure vdisk physical block size in vdc.conf
Previously, the workaround was to create the zpool on the control domain with the original ssd-config-list entry for ZFSSA in ssd.conf and export zfs volume dataset to the guest domain.
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