User's Manual

a. Comment out the back end PERC virtual disk entry so the --mount results shown

in /etc/fstab is displayed as follows:

#/dev/sdd/data1 ext4 defaults 1 2

/dev/fldc0/data1 ext4 defaults 1 2

b. To determine if your edit of the /etc/fstab file has fixed the issue, run the

command: fldc --list --disk. If the system returns available for

fldc0, the issue is resolved.

• An existing Fluid Cache disk cannot be displayed if the Fluid Cache license is missing

or expired. To verify if your Fluid Cache license is valid, run the command: fldc --

status --license. To resolve a licensing issue, contact Dell Sales.

NOTE: If you obtain a new license, you must disable caching before you can apply

the new license.

Fluid Cache Disk Status Has Failed

Probable Cause

• A supported disk is displayed, but enabling caching fails, because PERC presents a

failed disk.

• The back end PERC virtual disk is already mounted.

Solution

• If the back end PERC virtual disk fails, Fluid Cache for DAS can no longer flush dirty

blocks, so I/O's also fail. However, the dirty blocks remain safe in the cache and are

not lost. The following may be the cause(s) of failure:

– The disk enclosure may appear to have no power or appear disconnected.

– The PERC card may have failed.

– Cables may be disconnected.

– The single disk behind the PERC card may have failed, is powered off, or got

disconnected.

– Multiple disks behind the PERC card may have failed.

Fluid Cache reports I/O failures as the result of any of the above issues. To resolve

issues on back end PERC virtual disks behind the PERC card, see the

Dell PowerEdge

RAID Controller (PERC) User’s Guide

for the version of PERC used in your system (H710,

H710P or H810).

After the problem with the PERC card or a back end PERC virtual disk is resolved,

reactivate caching on the back end PERC virtual disk. Run the command: fldc --

reactivate --disk=<disk_name>. After caching is enabled, Fluid Cache for

DAS flushes the dirty blocks in cache to disk.

• If you cannot reactivate, the disk may already be mounted. Check the disk status by

running the command: fldc --status --disk=<disk_name>. If the status

shows that the disk is already mounted, see the topic “Fluid Cache Disk Does Not

Appear” in this section to resolve any issue with the /etc/fstab file.

If the issue persists, contact Dell Technical Support.

Cache Status Is Displayed As Degraded

Probable Cause

• Not enough PCIe SSDs are plugged in to support Write-Back (WB) mode.