CacheCade Using Solid State Drives

CacheCade is used to improve random read performance of the Hard Disk Drive (HDD) based Virtual Disks. A solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data. SSDs significantly increase the I/O performance (IOPS) and/or write speed in Mbps from a storage device. With Dell Storage Controllers, you can create a CacheCade using SSDs. The CacheCade is then used for better performance of the storage I/O operations. Use either Serial Attached SCSI (SAS) SSDs or Serial Advanced Technology Attachment (SATA) SSDs to create a CacheCade.

Create a CacheCade with SSDs in the following scenarios:

Maximum application performance—Create a CacheCade using SSDs to achieve higher performance without wasted capacity.
Maximum application performance and higher capacity—Create a CacheCade using SSDs to balance the capacity of the CacheCade with high performance SSDs.
Higher capacity—If you do not have empty slots for additional HDDs, use SSDs and create a CacheCade. This reduces the number of HDDs required and increases application performance.

The CacheCade feature has the following restrictions:

Only SSDs with the proper Dell identifiers can be used to create a CacheCade.
If you create a CacheCade using SSDs, the SSD properties are still retained. At a later point of time, you can use the SSD to create virtual disks.
A CacheCade can contain either SAS drives or SATA drives but not both.
Each SSD in the CacheCade does not have to be of the same size. The CacheCade size is automatically calculated as follows:
CacheCade size =capacity of the smallest SSD * the number of SSDs

The unused portion of SSD is wasted and can not be used as an additional CacheCade or an SSD-based virtual disk.

The total amount of cache pool with a CacheCade is 512 GB. If you create a CacheCade which is larger than 512 GB, the storage controller still uses only 512 GB.
The CacheCade is supported only on Dell PERC H700 and H800 controllers with 1 GB NVRAM and firmware version 7.2 or later.
In a storage enclosure, the total number of logical devices including virtual disks and CacheCade(s) cannot exceed 64.
NOTE: In order to use CacheCade for the virtual disk, the Write and Read policy of the HDD based virtual disk must be set to Write Back or Force Write Back and read policy must be set to Read Ahead or Adaptive Read Ahead.

Manage CacheCade

Ensure that SSDs are available in the storage enclosure before performing any CacheCade operations. To create, resize, blink, or delete the CacheCade, go to the CacheCade(s) screen:

1 In the Dell OpenManage Server Administrator window, click Storage.
2 Go to Storage Dashboard Storage ControllerAvailable Tasks and select Manage CacheCade.
3 Click Execute.

The CacheCade(s) screen is displayed.

Creating a CacheCade

To create a CacheCade:

1 In the CacheCade(s) screen, click Create CacheCade. The Create CacheCade screen is displayed.
2 In the CacheCade Group section, select SATA SSD or SAS SSD if your system contains both SAS and SATA SSDs.
3 Enter a name for the CacheCade. The size is calculated as follows:

CacheCade size = capacity of the smallest SSD * the number of SSDs

4 From the available free disks that are displayed, select the SSDs that you would like to include in the CacheCade. The selected disks are displayed in the Physical Disks Selected section.
5 Click Finish.
NOTE: The procedure of selecting physical disks while creating a CacheCade is similar to the selection of disks while creating a virtual disk. For more information, see Create Virtual Disk Advanced Wizard (Step 2 of 4).

Resizing the CacheCade

To resize the CacheCade:

1 In the CacheCade(s) screen, go to the CacheCade that you want to resize and select Resize ... from the Tasks drop-down menu.

The Resize CacheCade(s) screen is displayed.

2 From the available CacheCade(s), add or remove additional CacheCade(s) as required. The disks that you select are displayed in the Selected Physical Disks section.
NOTE: While selecting and deselecting the SSDs that must participate in the CacheCade, you must retain at least one of the original SSDs.
3 Click Finish.

Renaming the CacheCade

1 In the CacheCade(s) screen, go to the CacheCade that you want to rename and select Rename ... from the available Tasks.
2 In the Rename screen, enter the new name for the CacheCade and click Finish.

Blinking and Unblinking the CacheCade

In the CacheCade(s) screen, go to the CacheCade that you want to blink and select Blink... from the available Tasks.

The LED of the physical disk(s) participating in the CacheCade glows.

To unblink the physical disk in the CacheCade(s) screen, go to the CacheCade Disk that you want to unblink and select Unblink... from the available Tasks.

Deleting the CacheCade

To delete the CacheCade:

1 In the CacheCade(s) screen, go to the CacheCade that you want to delete and select Delete... from the available Tasks.

The following warning is displayed: Warning! CacheCade pool size will be reduced. Do you want to continue with the delete operation?

2 Click Delete.

CacheCade Properties

The CacheCade(s) screen displays a table of properties for each CacheCade. The following table provides a description for each property.

Table 14-1. CacheCade Properties

Property

Definition

Status

These icons represent the severity or health of the storage component.

Normal/OK

Warning/Non-critical

Critical/Fatal

For more information, see Storage Component Severity.

Name

This property displays the name of the CacheCade. The link enables you to access the physical disks that constitute the CacheCade.

Tasks

This drop-down list provides the available tasks for the CacheCade.

Size

This property provides the size of the CacheCade.

Bus Protocol

This property displays the technology that the physical disk is using. Possible values are SAS and SATA.

Disk Cache Policy

This property displays whether the disk cache policy of the physical disks that are part of the CacheCade is Enabled or Disabled.

See RAID Controller Read, Write, Cache, and Disk Cache Policy.