Administrator Guide

Fluid Cache Volumes
A Fluid Cache volume extends a normal Storage Center volume to be contained across the cache devices in a Fluid Cache cluster as
well as permanently stored in the
Storage Center volume.
Limitations for Fluid Cache Volumes
There are a number of considerations before utilizing a volume in a Fluid Cache cluster:
• Fluid Cache volumes cannot be expanded
• Fluid Cache volume Read and Write Cache options are not available
• Fluid Cache volumes cannot be the source or destination of Live Volumes
• Fluid Cache volumes cannot be the destination of a replication
• Fluid Cache volumes cannot be part of a synchronous replication or simulation thereof
Managing Fluid Cache Volumes
The following tasks describe how to add and remove volumes from Fluid Cache clusters.
Add a Volume to a Fluid Cache Cluster
Use Storage Manager to add a volume to a Fluid Cache cluster. Volumes used in a Fluid Cache cluster cannot be expanded, so the
creation of volumes must be thought out ahead of time to ensure the space necessary is available.
1. Click the Storage view.
2. In the Storage pane, expand Storage Centers if necessary and select the Storage Center containing the volume to include in
the cluster.
3. In the Storage tab, expand the Storage Center and expand Volumes.
4. Select a volume and click Map Volume to Server. The Map Volume to Server dialog box appears.
5. Select a server to include in the cluster and click Next.
6. Select Enable Fluid Cache and select a Host Cache Policy (Write Back is selected by default).
• Write Back: In addition to caching reads, write-back mode allows the caching of writes without incurring the penalty of
waiting for the disk to acknowledge the writes. Write-back caching requires a PCIe SSD on two or more cache servers in
the cluster. (If there is only one cache device, Write Back is unavailable.)
• Write Through: Forces writes to both the cache and the disk simultaneously. Warm reads and read-after writes are
accelerated but writes are not. Write-through caching requires only one PCIe SSD on one of the cache servers in the
cluster.
• Bypass (rarely used): Generally used only if the cache devices are not available or not functioning. This setting would be
used temporarily until the situation is rectied.
7. (Optional) Select Keep cached data on the node that accessed the data. Selecting this check box may result in a
performance improvement since all data is kept on the local cache device(s). If this box is not checked, cache data is evenly
distributed across all cache devices.
8. Click Finish
Remove a Volume From a Fluid Cache Cluster
Use Storage Manager to remove a volume from a Fluid Cache cluster while maintaining the cluster and the volume.
1. Click the Storage view.
2. In the Storage pane, expand Storage Centers if necessary and select the Storage Center with the mapped volume.
3. In the Storage tab, expand Volumes, select the volume to be removed and click Remove Mappings. The Remove Mappings
[ volume name ] dialog box appears.
4. Select the volume to unmap and click OK.
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Dell Fluid Cache for SAN Cluster Administration