MSA20 RAID 5 two identical drives

[j bohg]

Hey there, I'm still a bit confused about the whole thing. I understand why we only have 1,43Tb of free disk space, that comes from using a spare in our configuration. Is it wise to make a new configuration without using an spare? And what is the difference between a Spare and a Hot Spare?

[Uwe Zessin]

It depends on how much value you put on the availability of your data (no, I'm not trying to be funny). A spare disk will immediately be used to rebuild redundant information when a disk drive has gone bad.
Otherwise you have to monitor your system and manually swap the disk. You do have an unused disk lying around? Can you afford to run without RAID protection until a replacement part has been shipped to you?

(hot) spare or not. I've once read the definition that a 'hot' spare is already spinning while a 'simple' spare is not.
Unfortunately, different arrays use different terminology and these days disk drives are starting automatically anyway. By that definition, all spares are 'hot'.

[j bohg]

Many thanks for all the answers. It certainly helped me out a lot and things are a lot clearer to me.

Stil one question left and that is why I see two new identical drives in Windows Explorer with the same amount of free space but different drive-letters. I just did a complete new configuration and deleted the old one. As soon as I assigned a drive letter to the logical drive in Disk Management the two drives became visible. In disk management only one disk is visible. Any explanation would be helpful.

[j bohg]

I'm still confused about the two disks in the Explorer. Last night I did a new test on the logical drive, wich I called drive R in Disk management. I created a folder on the disk and somehow it seemed to be mirrored to the other disk. Question is how can it be that I see two identical drives, both with 2Tb, while I only have one logical drive with a 2Tb capacity.
When opening properties I noticed that the server sees two logical volumes while only having one. I included a screenshot from this. It says that write caching is enabled. Could this be the reason, that the server created one drive for caching? Would that also be the reason that I cannot see the second drive (I) in disk management?

[Uwe Zessin]

Very strange. It _looks_ like there are two paths to the same data, but I don't see how this is possible in your configuration... Is there some add-on software that can create block-based snapshots?

Is there anything interesting in the Windows Event Log?
Can you attach the output from the following command as a text file (no Word document ;-), please?
+----
C:\>reg query HKLM\HARDWARE\DEVICEMAP\Scsi /s > scsi_%COMPUTERNAME%.txt
----

[j bohg]

Thanks for your reply Uwe, I looked in the event log but couldnt find anything usefull. I attached the file you requested and hope it is usefull. Thanks in advance!

[j bohg]

Hey Uwe, as you requested I attached the txt file in my previous reply. If you have a spare minute I would really appreciate it if you could run through the document to see if there's anything wrong.

many thanks in advance!

[j bohg]

Perhaps there is someone else who understands the output in the attached file? Any help would be greatly appreciated.

[Uwe Zessin]

I'm sorry, I have lost track of this thread - thanks for the reminder...

There a two disks which are seen through the same controller port:

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 5\Scsi Bus 1\Target Id 0\Logical Unit Id 0

HKEY_LOCAL_MACHINE\HARDWARE\DEVICEMAP\Scsi\Scsi Port 5\Scsi Bus 1\Target Id 1\Logical Unit Id 0

Can you open the device manager and use [View->Devices by connection]? This gives a hierarchical overview. I'll attach a picture with an example drill-down.

[j bohg]

Hey Uwe, great to hear from you. I understand that you cant keep track of all treads. Thanks for your reply, I attached the image you requested. Hope this will make sense.