Expanding the media file system by bandwidth

If you want to retain your media file system and yet expand the bandwidth of your K2 SAN, you must use the following procedures for dynamic bandwidth expansion. This process allows you to add RANKs to the stripe group, thereby expanding its width, without reinitializing the file system. This keeps the existing media intact. The additional RANKs can be made up of new disks in existing RAID chassis, disks in new Expansion Chassis, or disks in new primary RAID chassis.

After the file system is expanded, existing media is still striped across the original narrower stripe group, so it can not take advantage of the increased bandwidth. Also, if there is a significant portion of the storage pool occupied by this existing media, its presence reduces the extent to which new media can use the increased bandwidth. For this reason the dynamic bandwidth expansion process provides the Restripe Utility, which restripes the existing media across the new wider stripe group. This enables both the existing media and new media to get full benefit of the increased bandwidth.

If the media on your file system has a high turnover rate and you know existing media is to be deleted soon, you have the option of disabling the Restripe Utility. This saves the system resources and time required to restripe media.

The expansion chassis that you add to your K2 SAN must have unbound, unlabeled disks. If it currently has disks bound or labeled, connecting it to your system can cause errors.

Dynamic bandwidth expansion is supported only with K2 system software version 3.2 and higher.

Dynamic bandwidth expansion is supported on systems with one LUN per RANK and on systems with multiple LUNs per RANK.