Before you can install an operating system on a PowerEdge server with a PERC RAID controller, the drives usually need to be grouped into a virtual disk (VD). This guide shows how to do that locally, before the OS is installed, using the PERC configuration utility inside System Setup, which Dell calls the HII (Human Interface Infrastructure) Configuration Utility. The steps are taken from the Dell PERC 11 User's Guide (H755, H750, H355, H350) and the Dell PERC and HBA Controllers Unified User's Guide (H975, H965, H365 series, which includes PERC 12).
Before you start
- Back up any data on the drives you plan to use. Creating a virtual disk with initialization, or reusing drives that held an old array, can destroy existing data.
- Know which RAID level you need and how many drives it takes. See choosing a RAID level by workload.
- You need a console on the server: a local monitor and keyboard, or the iDRAC virtual console (iDRAC9 virtual console guide).
- Check your controller model. Some options and RAID levels differ between PERC 11 and PERC 12, and between full-featured and entry models.
What differs between PERC 11 and PERC 12
The menu path is the same on both families, but the available values differ. The table summarises what the two Dell user guides document.
| Item | PERC 11 (H755, H750, H355, H350) | PERC 12 (H965, H365 series) |
|---|---|---|
| RAID levels | 0, 1, 5, 6, 10, 50, 60. RAID 5, 6, 50 and 60 are not supported on H355 and H350 models | H965 series: 0, 1, 5, 6, 10, 50, 60. H365 series: 0, 1, 10 |
| Strip element size | 64 KB, 128 KB, 256 KB, 512 KB, 1 MB (default 256 KB) | 64 KiB and 256 KiB |
| Default read policy | Read Ahead | No Read-Ahead (Read-Ahead is supported only on hard drives) |
| Write policy | Write Back (default) or Write Through | Write-Back (default), Write-Through or Force Write-Back |
| Drive filters | Unconfigured Capacity or Free Capacity | Also filter by media type, interface (SAS, SATA, NVMe) and logical sector size |
For older PERC 9 or PERC 10 controllers the HII screens are similar, but option names can differ. Check the user guide for your exact controller. Dell lists which cards belong to each PERC family in its PERC types article.
Step 1 — Open the PERC configuration utility
- Power on or restart the server.
- While the server starts, press F2 to open System Setup.
- Click Device Settings. The list shows the RAID controllers (and NIC ports) in the server.
- Click your PERC controller. The Dashboard View opens with the Main Menu, controller status and any background operations in progress.
Note: Dell notes that some options are hidden if the controller does not support the feature, or greyed out if it does not apply to the current configuration. Use Help in the top-right corner for a description of each option.
Step 2 — Make sure the drives are available for RAID
Only drives that are RAID-capable and unconfigured can be used for a new disk group. A drive that is set as non-RAID is presented directly to the OS and must be converted first.
- Go to Main Menu > Physical Disk Management and select the drive.
- From the Operations drop-down, select Convert to RAID capable, click Go, select Confirm and click Yes.
On PERC 12 the same action is also under Main Menu > Configuration Management > Convert to RAID-Capable. If drives show as foreign because they came from another server, deal with that first: see PERC foreign configuration: import or clear.
Step 3 — Choose the RAID level and drives
- Click Main Menu > Configuration Management > Create Virtual Disk.
- Select the RAID level.
- Under Select Physical Disks From, choose Unconfigured Capacity to build a new disk group, or Free Capacity to use unused space in an existing disk group.
- Click Select Physical Disks (or Select Disk Groups for free capacity). On PERC 12 you can filter by media type, interface and sector size first.
- Tick the drives, then click OK. On PERC 12, click Confirm and Yes, then OK to reach the parameters section.
Mixing rules matter. The PERC 11 guide states that a virtual disk cannot mix NVMe with SAS or SATA drives, or hard drives with SSDs, and cannot mix 512-byte and 4 KB native drives. On PERC 12, Dell does not support mixing TCG Enterprise and TCG Opal self-encrypting drives in one virtual disk.
Step 4 — Set the virtual disk parameters
- Virtual Disk Name: on PERC 11 the allowed characters are A-Z, a-z, 0-9, underscore and hyphen.
- Virtual Disk Size: defaults to the maximum available. Enter a smaller value if you want more than one VD on the same disk group.
- Strip Element Size: keep the default unless your application vendor recommends otherwise (see stripe size basics).
- Read Policy and Write Policy: Write Back is the default. On PERC 11, Dell explains that write-back is used when the battery is present and in good condition, and recommends a power backup system if you force write-back without one. More in write-back vs write-through.
- Disk Cache (PERC 12: Disk Write Cache Policy): Default, Enable or Disable.
- Default Initialization: No, Fast or Full (default No).
Warning: Fast and Full initialization erase files and file systems on the virtual disk. Fast overwrites the first and last 8 MB (boot records and partition tables). Full overwrites every block. Only initialize drives whose data you no longer need. Back up first.
What each option does, according to Dell:
- Fast takes a few seconds and is followed by a background initialization (BGI).
- Full writes the whole disk, so no BGI is needed afterwards. The host cannot access the VD while it runs. If the server reboots during a full initialization, it stops and a BGI starts instead.
- No leaves existing data in place. Redundant VDs still get a BGI.
Step 5 — Create the virtual disk and check it
- Click Create Virtual Disk, then Confirm and Yes.
- Open Main Menu > Virtual Disk Management and select the new VD. Its status should be Optimal. Use View Associated Physical Disks to confirm the right drives were used.
- Click Finish on the System Setup main menu and confirm with Yes to exit.
On RAID 1, 5, 6, 10, 50 and 60, a BGI starts automatically to write mirror or parity data. It does not run on RAID 0. Dell notes that BGI cannot be disabled permanently (it restarts within five minutes if cancelled) and that performance is lower until it finishes. On PERC 11, Dell also recommends restarting the system after creating a VD on drives that previously had boot partitions.
Shortcuts: Auto Configure RAID 0 and profiles
Configuration Management also offers Auto Configure RAID 0, which creates a RAID 0 VD on all drives in Ready state, and Create Profile Based Virtual Disk, which offers presets such as Generic RAID 1, 5 or 6. RAID 0 has no redundancy, so one failed drive loses the whole VD. Use it only for scratch data.
Frequently asked questions
Can I create the virtual disk without rebooting into F2?
Yes. iDRAC9 can create a VD remotely and apply it now or at the next reboot. See create a PERC virtual disk from iDRAC9. Dell notes that a VD created from iDRAC is fast-initialized.
Should I choose Fast or Full initialization for a new server?
Both erase data. Fast is quick and lets BGI build redundancy in the background. Full takes longer and blocks host access while it runs, but no BGI is needed afterwards.
Checklist
- Data on the target drives is backed up or not needed.
- Drives are RAID-capable, unconfigured and not foreign.
- RAID level is supported by your PERC model.
- Name, size, strip size, cache policies and initialization set on purpose, not by accident.
- New VD shows Optimal in Virtual Disk Management; BGI progress noted.
- Server restarted if the drives held old boot partitions.
Skyline can supply, configure and maintain Dell, HPE and Huawei servers under an annual maintenance contract (AMC). Contact us.
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