About the site-aware read policy

Site-aware read policy is a SFW feature that enhances the I/O read performance. To enhance the read performance, SFW services read I/Os from the plexes at the local site where an application is running. The I/O writes are written to plexes at all sites. By tagging hosts with site information, SFW identifies which hosts belong to which site. The I/O reads initiated by a host from one site are then satisfied by the disks which are tagged with the same site. Tagging hosts and disks with correct site information gives you maximum read performance with the site-aware read policy feature.

Note:

The site-aware read policy feature is applicable only for the Site Separated volumes.

The site-aware read policy feature works only if a host is tagged and at least one plex of the site-separated volume resides on disks with the same tags as the host. Also, if a host is tagged, but there are no local site disks available, then the plexes are read sequentially in a "round-robin" fashion. When there is more than one local plex, one of them is chosen as the preferred plex for site-aware read policy.

Note:

If any plex is set as a preferred plex to improve I/O performance, then the site-aware read policy feature is not implemented.

If a volume fails over to a site without local plex, then the site-aware read policy becomes the "round-robin" read policy in which the preferred plex that is set before the failover no longer remains applicable.