Managing RAID Disk Allocation on 22XXX Series SDX Appliances
Citrix ADC SDX 22040/22060/22080/22100/22120 appliances now include a Redundant Array of Independent Disks (RAID) controller, which can support up to eight physical disks. Multiple disks provide not only performance gains, but also enhanced reliability. Reliability is especially important for a SDX appliance, because the appliance hosts a large number of virtual machines, and a disk failure affects mulitple virtual machines. The RAID controller on the Management Service supports the RAID 1 configuration, which implements disk mirroring. That is, two disks maintain the same data. If a disk in the RAID 1 array fails, its mirror immediately supplies all needed data.
RAID 1 disk mirroring combines two physical drives in one logical drive. The usable capacity of a logical drive is equivalent to the capacity of one of its physical drives. Combining two 1-terabyte drives, for example, creates a single logical drive with a total usable capacity of 1-terabyte. This combination of drives appears to the appliance as a single logical drive.
The SDX appliance is shipped with a configuration that includes logical drive 0, which is allocated for the Management Service and Citrix Hypervisor, and logical drive 1, which is allocated for Citrix ADC instances that you will provision. To use additional physical drives, you have to create new logical drives.
Viewing Drive Properties and Operations
A SDX appliance supports a maximum of eight physical-drive slots, that is, a pair of four slots on each side of the appliance. You can insert physical drives into the slots. Before you can use a physical drive, you must make it part of a logical drive needs.
In the Management Service, the Configuration > System > RAID screen includes tabs for logical drives, physical drives, and storage repositories.
On the Configuration > System > RAID > Logical Drives tab, you can view the name, state, size, of each logical drive, and information about its component physical drives. The following table describes the states of the virtual drive.
|Optimal||The virtual drive operating condition is good. All configured drives are online.|
|Degraded||The virtual drive operating condition is not optimal. One of the configured drives has failed or is offline.|
|Failed||The virtual drive has failed.|
|Offline||The virtual drive is not available to the RAID controller.|
You can also view the details the physical drives associated with the logical drive by selecting the logical drive and clicking Show Physical Drive.
To create a new logical drive
- Navigate to Configuration > System > RAID, and select the Logical Drives tab.
- Click Add.
- In the Create Logical Disk dialog box, select two slots that contain operational physical drives, and then click Create.
A SDX appliance supports a maximum of eight physical slots, that is, a pair of four slots on each side of the appliance. On the Configuration > System > RAID > Physical Drives tab, you can view the following information:
- Slot—Physical slot associated with the physical drive.
- Size—Size of the physical drive.
- Firmware State—State of the firmware. Possible Values:
- Online, spun up—Physical drive is up and is being controlled by RAID.
- Unconfigured (good)—Physical drive is in good condition and can be added as a part of the logical drive pair.
- <Unconfigured (bad)—Physical drive is not in good condition and cannot be added as part of a logical drive.
- Foreign State— Indicates if the disk is empty.
- Logical Drive— Associated logical drive.
In the Physical Drives pane, you can perform the following actions on the physical drives:
- Initialize—Initialize the disk. You can initialize the physical drive if it is not in good state and needs to be added as a part of logical drive pair.
- Rebuild—Initiate a rebuild of the drive. When a drive in a drive group fails, you can rebuild the drive by re-creating the data that was stored on the drive before it failed. The RAID controller re-creates the data stored on the other drives in the drive group.
- Locate—Locate the drive on the appliance, indicated by causing the Drive Activity LED associated with the drive to blinnk.
- Stop Locate—Stop locating the drive on the appliance.
- Prepare to Remove—Deactivate the selected physical drive so that it can be removed.
On the Configuration > System > RAID > Storage Repository tab, you can view the status of storage repositories on SDX appliance. You can also view information about a storage-repository drive that is not attached, and you can remove such a drive by selecting the it and then clicking Remove. The Storage Repository tab displays the following information about each storage repository:
- Name—Name of the storage repository drive.
- Is Drive Attached—Whether the storage repository is attached or not. If the drive is not attached, you can click Remove to delete.
- Size—Size of the storage repository.
- Utilized—Amount of storage-repository space in use.
Adding One Addtional Logical Drive to the SDX 22000 Appliance
To add an addtional logical drive to the SDX 22000 platform:
- Log on to the Management Service.
- Navigate to Configuration > System > RAID.
- On the back of the SDX 22000 appliance, insert the two blank SSDs in slot numbers 4 and 5. You can add the SSDs in a running system.
Note: Make sure that the SSDs are Citrix certified.
- In the Management Service, navigate to Configuration > System > RAID and the Physical Drives tab. You would see the SSDs that you added.
- Navigate to the Logical Drive tab and click Add.
- In the Create Logical Disk page:
- In the First Slot drop-down list, select 4.
- In the Second Slot drop-down list, select 5.
Note: In Management Service, the slot number begins with zero. So the slot numbering in Management Service differs from the slot numbering on the physical appliance.
The logical drive is created and is listed under the Logical Drive tab. Click the refresh icon to update the order of the logical drives.
Adding Second Additional Logical Drive on the SDX 22000 Appliance
To add another logical drive, insert the SSDs in slot numbers 6 and 7. In the Create Logical Disk page, select 6 from the First Slot drop-down list and select 7 from the Second Slot drop-down list.
#### Replacing a Defective SSD Drive with a Blank SSD Drive
To replace a defective SSD drive with a blank SSD drive:
- Navigate to Configuration > System > RAID.
- On the Physical Drives tab, select the defective drive that you want to replace.
- Click Prepare to Remove to remove the drive.
- Click the refresh icon to refresh the list of physical drives.
- Physically remove the defective drive from the slot.
- Insert the new Citrix verified SSD in the slot from where you removed the defective SSD.
- In the Management Service, nagivate to Configuration > System > RAID. The new SSD is listed in the Physical Drives section. The drive rebuild process starts automatically.
Click the refresh icon to check the status of the rebuild process. When the rebuild process is complete, you can see Online, Spun Up status in the Firmware State column.