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MD3xxx - Access Virtual Disk mapped to each Host?
As we have just received our first Powervault MD38xxi, I am now playing around with it to get myself familiar with this box.
The intention is to use this storage as backup-destination for various platforms, thru various backup-applications (Veeam, MS DPM, Unitrend UVB ++)
As we intend to use the MD3860i only with iSCSI, we will have no direct attached servers connected to it, and plan to manage it thru "Out-of-Band" management only.
Now I have noticed, that for every host I create and connect to the MD3860i, there is created an "Access"-LUN, that is made visible to the iSCSI-host on connect.
As I have been searching for the purpose of this "Access"-LUN, if it could be deleted, has to be initialized, or what else, I have only come across a very limited description of it in the MSDM User-guide:
Quote...:
Each RAID controller in an MD Storage Array maintains an access virtual disk. The host-agent software uses the access virtual disk to communicate management requests and event information between the storage management station and the RAID controller module in an in-band–managed storage array. The access virtual disk is not available for application data storage. The default LUN is 31.
NOTICE: Removing or manipulating an access virtual disk can cause a loss of management access. If you remove an access virtual disk mapping from an in-band-managed storage array, MD Storage Manager can no longer access the storage array. Do not modify the access virtual disk either in the operating system or with MD Storage Manager.
....Quote end
That is all description/explaining I have been able to find within reasonable time...
So.. my questions:
1. It is unclear to me, if this Access-disk has to be initialized on the host? Or shall it just stay there un-initialized?
2. Is the Access-disk at all needed, when only doing out-of-band management, and intentions are NOT to install Dell's Host Software on attached hosts, but only use OS-native MPIO providers (primarily MS iSCSI MPIO)?
3. Can the Access-disk somehow be removed from the LUN's presented to the indiviual hosts?
Regards, Mikael K
DELL-Sam L
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February 20th, 2017 11:00
Hello Mikael,
Please let us know if you have any other questions.
mikaelkolbe
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February 22nd, 2017 01:00
Hello Sam.
Thank you for the reply...
However, I have to ask you to elaborate/investigate a bit more on the answer about MPIO-driver...
You state that we have to use MPIO-drivers from the Dell MD resource-disk, as MS MPIO will not work correctly..? In what regards do you mean it will not work correctly?
I have been testing on the MPIO-function, and after manually configuring MS iSCSI (*), with 1 session with 2 identifiers with dual path against each RAID-controllers in the MD, I have not been able to get disconnect fro the MD while yanking all but one network-cable of the iSCSI-paths (including reconnect one, and then yanking the last)...
(*) If configured by the MD Config Utility, without Dell DSM installed (see note below), the utility does create a mess in iSCSI-connections, with 4 individual sessions against each IP on the MD, with one path per session, each configures as "round robin".. Of course, here I can doubt if that will provide a working MPIO-config
Note: I think Dell should emphasize or do a installation pre-check, that the MD Ressource DVD has to be locally attached to the server when installed. If running the istaller from a network-share, the Dell DSM will NOT be installed!