Users Guide

Volume Thin-Provisioning Configuration
Parameters
Configuration parameters in /etc/equallogic/eql.conf control the behavior of the eqlvolume rethin command. The
eqlvolume tool uses these parameters, with file system and EqualLogic volume characteristics, to determine if a volume can be thin-
provisioned. For information on these characteristics, see Considerations for Thin-Provisioning.
The following table describes the volume thin-provisioning configuration parameters.
Table 39. Volume Thin-Provisioning Configuration Parameters
Parameter Default Value Description
ReThinRecommend 3 Specifies the minimum percentage of available space required. If the
percentage of space used by the target minus the percentage of space used
by the file system is greater than or equal to the value specified in this
parameter, the file system is recommended for volume thin-provisioning.
Use this parameter to configure volume thin-provisioning on small storage
volumes.
ReThinRecommendMB 2048 Specifies the minimum size (MB) of available space required. This value
must be larger than 15. If the space used by the target minus the space used
by the file system is greater than or equal to the value specified in this
parameter, the file system is recommended for volume thin-provisioning.
Use this parameter to configure volume thin-provisioning on large storage
volumes.
ReThinHeadroom 2 Specifies the minimum percentage of free space that must exist. This value
is also the minimum percentage of free space that must be left unallocated
if a file system is thin-provisioned. This value is not used on systems where
FITRIM ioctl is supported.
On systems where FITRIM ioctl is not supported, this parameter and
ReThinHeadroomMB ensure that free space is reserved for users during
thin-provisioning.
Use this parameter to manage free space available on the storage volume.
NOTE: If the file system is particularly active and allocation
failures occur for user applications while thin-provisioning is
taking place, increase this parameter and/or
ReThinHeadroomMB.
ReThinHeadroomMB 15 Specifies the minimum amount of free space, as a fixed limit in MB, that
must exist for a volume to be thin-provisioned. This value is also the
minimum amount of free space to be left unallocated if a file system is thin-
provisioned. This value is not used on systems where FITRIM ioctl is
supported.
On systems where FITRIM ioctl is not supported, this parameter and
ReThinHeadroom ensure that free space is reserved for users while thin-
provisioning takes place.
NOTE: If the file system is particularly active and allocation
failures occur for user applications while thin-provisioning is
taking place, increase this parameter and/or ReThinHeadroom.
Show Mount Point Information
Use the eqlvolume show command to locate the file systems, or mount points, supported by EqualLogic volumes and to display
characteristics of those mount points and volumes.
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Managing Thin-Provisioned Volumes