vFlash for DRAC -- lifesaver in OS install via VPN and server recovery after crash

vFlash as an essential tool for "confined to home" system administrator
and any sysadmin who works with remote servers via VPN

• Introduction
• vFlash SD card
• Loading ISO into vFlash partition
• Booting from vFlash partition
• vFlash partition management
• Summary

Introduction

Enterprise version of iDRAC provides very interesting and useful additional functionality:  vFlash card. This card which can be 8GB or 16GB can be managed through several front-ends including iDRAC GUI,  RACADM Command Line Interface (CLI).  Interface is semi-debugged  but still if you use just one 2GB partition is usable. The max size of partition created is limited to 2GB. So this is suitable for boot disks and recovery disks but not can't accommodate the full ISO.  It's value is evident only if you need to administer a remote server via VPN.

vFlash provides the USB  device emulation. It allows  iDRAC to share the partition data with the server operating system through the iDRAC built-in USB hub as an external hard disk drive (HDD), an optical drive (CD or DVD), or a flash memory device (FD). The emulated iDRAC USB device goes online when the operator attaches a vFlash partition.

Unlike regular USB drive its content can be updated remotely through the iDRAC GUI using DRAC network interface.  So in a way this is remotely controlled USB drive. This is the major attraction both as an installation tool (you are limited to 2GB ISO though, so boot from minimal ISO) or as a troubleshooting tool.

With ISO only two operations are supported:

• Creating a partition from an ISO
• Writing a partition as ISO to server disk.

Some of the applications of vFlash include:

• Download a custom ISO image, and instruct the BIOS to boot to it.  You can do it even if there is OS on the server or blade. The limit of image is unfortunately limited to 2GB, so you can't download full Red Hat ISO DVD image. But you can use minimal image which is less then one gigabyte.It is most commonly used function
• As the inviolable storage space to back up and restore system or OS configurations (such as previous versions of DRAC. ) Store data or backup critical files for the OS, users or applications installed.  For example you can backup Linux /etc directory to one the partition of the card.
• Back up and restore you DRAC settings, etc in case you need to replace the motherboard.

vFlash SD card

Dell vFlash media inserts into the iDRAC enterprise daughter card on  the back of the Dell 11th generation rack and tower servers. And  in front of  the Dell 12th generation rack and tower servers. Blades like M630 must be removed from their chassis to access this port. 

 You can use Dell-provided SD cards or your own as long as you have the iDRAC Enterprise license. The vFlash device supports most of the generic SD cards.

One of the key enabling technologies of vFlash is the emulation of the out-of-band storage space as in-band USB storage device(s). This allows the content of the emulated USB device to be accessed and prepared remotely. The emulated storage type can be Floppy, CD, or Hard drive. This is critical to a system operator where the physical access to a server system is not possible.

The SD card can be up to 16GB but  only a single partition is typically used and that means are only first 2GB are used so it makes sense order 8GB card.  Theoretically customers can use the space on the vFlash card to create up to 16 partitions in sizes ranging from 1MB to 2GB.

Users can expose the partition to the operating system  like a USB flash drive (attach operation).

Detached cards can physically moved to another supported Dell server.  When the card is removed from the server it can be accessed on any PC. Files can be copied, moved, etc.  Of course. that makes sense only for local back servers (in blades the removal of the card requires removing the blade form the enclosure.

vFlash provides a custom deployment environment that allows for the automation of server configuration, scripts, and imaging. Multiple boot media disks are no longer required as you can now have them embedded on vFlash partitions.

Loading ISO into vFlash partition

You can create vFlash partition by loading an ISO image into it. New partition is created, you can't load into existing partition. In this case you do not need neither create new partition or format it. The only significant limitation is the current 2GB limit on ISO size (despite 4GB limit on the size of partition). 

First you need to define the six symbol label of the partition, for example CENT77

After that you can start loading the ISO image. Dialog ask you to point to the ISO and if ISO is of suitable size the process started. It is quite slow.

This vFlash operation can be performed remotely without physical access to the system. This is a great convenience for a data center system administrator when physical access to a system is difficult.

NOTE:

If your download operation was interrupted (for example due to flaky TCP/IP connection from home computer to rempote server) vFlash is completely hosed.  You can't deleted this "aborted" partition (indicator stucks on some number for example 43% forever). You't even reinitialize the card. But resetting DRAC sometimes helps.

Booting from vFlash partition

What is important is that vFlash partitions can be made bootable which makes then  an excellent management tool for sysadmins that have low bandwidth, or high latency, links to the remotely managed server.  In other words, all sysadmins who manage servers via VPN.

vFlash interface uses the notion of "attached". The latter indicates whether this partition is visible to the operating system as a USB device. Including on boot.

To be able to boot from vFlash partition it needs to be attached. The label of the attached partition will be displayed in the boot menu (accessible via F11 on boot).

NOTE: It also can be set via Server/Setup

If you are attaching or detaching a partition, the USB bus of the system is reset. This may affect applications (like the operating system) that are using vFlash and will disconnect iDRAC Virtual Media sessions.

NOTE: The detached partitions are not displayed in the boot order.

With this option, vFlash provides a convenient bootable media storage space for rescue CD and such readily available on an un-configured bare-metal system.

On the other hand, vFlash can also serve as an out-of-band storage space for the systems management functions running on the iDRAC.

Because the same vFlash space can be shared by both the in-band and out-of-band applications, the out-of-band systems management can place contents on the vFlash to be shared with the system applications.

vFlash partition management

The vFlash partition is the basic management unit. vFlash service can then emulate the vFlash partition as a separate USB storage device.

For a new SD card, the operator must initialize the card before its space can be managed by the vFlash system. The initialization procedure reformats the card, erases all existing content, and creates proprietary system files on the card. Though the system files are not hidden, an operator must not alter the files in any manner. As a vFlash security measure, any alteration to the system files will render the card uninitialized. If this occurs, the operator needs to go through another vFlash initialization procedure to erase all existing content on the card.

After initialization, the vFlash storage space can be managed in partitions. An operator can create up to 16 vFlash partitions. Each partition can have a size up to 4GB. When the vFlash SD card is inserted into a Windows workstation, the operator can observe that the partitions are in fact proprietary image files on the SD card and not physical disk partitions.

An operator creates partitions in several different ways. One can create an empty vFlash partition and then format it into FAT, EXT2, or EXT3 file systems. An operator can also upload a partition to vFlash from a remote disk image, for example, CD/DVD ISO images. Conversely, the operator can save the partition data to a remote partition image file.

Summary

The vFlash system supports both graphical user interface and the scriptable command line interfaces. Through these interfaces, a system operator can manage and use the vFlash system remotely. The full scripting ability allows a system operator to tailor and automate the vFlash usage to any systems management applications.

The ability to remotely download an ISO image through the DRAC network interface   to a local storage device is a very powerful feature unique to Dell systems with Enterprise version of DRAC.

Recommended Links

• How to use vFlash via GUI/USC – explains how to manage vFlash devices from iDRAC GUI and Unified System Configurator
• Scripting vFlash partition management – explains how to manage vFlash devices through web service and command-line interfaces
• Using Dell vFlash by Cori Rizzo
• vFlash: An Overview
• http://dmtf.org/standards/wsman  Web Services for Management (WS-MAN):
• http://attachments.wetpaintserv.us/BMJk79WsVP3F0jwl50xR_w2088275  WSMAN Interface Guide for Linux:
• http://attachments.wetpaintserv.us/utYVFQFaHmnfG_LHEnx1YQ2026735 WSMAN Interface Guide for Windows:
• http://sourceforge.net/projects/openwsman/vFlash  An Overview 7 WSMAN command line open source for Linux (Openwsman)
• http://msdn.microsoft.com/en-us/library/windows/desktop/aa384291(v=VS.85).aspx  WSMAN command line for Windows (Winrm):

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Last modified: February 21, 2021