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AID-Controller does not see disks

Posted on 2011-03-01
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Last Modified: 2012-05-11
I have 24 2TB disks in my server controlled by an Adaptec 5405.
I added 4 RAID sets:
 2 x 2 TB 1x 1TB and one 15GB.

So there is plenty of space left. Interestingly enough though, when I want to add more sets the available disk list is empty. Why? I cannot create bigger Sets, because this server is for vmWare and ESX does not recognize disks greater than 2TB.

Thanks for your help.
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Question by:menefre
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15 Comments
 
LVL 5

Expert Comment

by:Darryl Allen
ID: 35009934
Is it possible that the block size that was setup in VMWare isn't big enough?  You may need a block size of 4k or 8k.  I think this involves removing the datastore in VMWare and then re-adding it with the new block size.
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Author Comment

by:menefre
ID: 35009981
The problem is a level deeper - on the actual RAID-CONTROLLER level. We are not even in vmWare.
The RAID-Controller cannot add additional arrays eventhough there is plenty of disk space.
It is as if the controller can add only 4 arrays, but that is nonsense. He can have up to 512.
So why can I not add an additional array, loosing 18TB of diskspace?
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LVL 47

Expert Comment

by:David
ID: 35010320
You will have to get a different controller.  This one can't handle the 16-byte SCSI CDBs necessary to get over the 2TB limit.  (Besides that controller is totally unsuitable for such a storage farm to begin with)   Get a LSI RAID controller that is on the VMWare certified list.  Be sure to get one with a battery backup unit for write cache or performance will be AWFUL)  

Specifically what make/model of disks(s) do you have?   I could have even more bad news for you depending on what disks you bought.

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Author Comment

by:menefre
ID: 35010468
The controller very well could get over the 2TB limit and he is vmWare certified. He also has a BU unit.
I setup the 2TB limit intentionally because vmWare cannot handle LUNs bigger than 2TB, otherwise I would have made one array with 20TB which is, of course, possible with this controller.
Again, the disks are 2TB, so no problem here.
And sorry, there are just 12 of them. Made a mistake in the original question.

So again:
- 12 disks (2TB each)
- 4 RAID5 Arrays (together 6TB)

And now on CONTROLLER LEVEL I cannot add another ARRAY. Please forget about vmWare. Maybe this was to much information.
My problem is before any OS starts in the ARRAY CONTROL UNIT (ACU) of the Adaptec controller.
The list of available disks is empty despite the fact that there is still much space.
I can see and edit the existing Arrays but I cannot add an additional one.
Why?
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LVL 47

Expert Comment

by:David
ID: 35014141
From the release notes ...

Exceeding 2TB LUN Size on VMware ESX Server
Under VMware, if you create a logical drive with greater than 2TB of capacity, the OS will only be able to access the remaining storage above 2TB. For instance, with the 3.5TB LUN, only 1.5TB will be accessible; with a 5TB LUN, only 1TB will be accessible (first 2TB+2TB are skipped); and so on.

So simply (well, painfully blow away those 4x RAID5s and make 6 x 2 TB RAID1s.  That is the most you can get out of this.
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LVL 47

Expert Comment

by:David
ID: 35014171
Or, if VMware VMDirectPath I/O supports this controller, then buy a few more controllers, and configure a few of those 3+1 RAID5s of yours, where each goes on it's own adapter, and you don't virtualize the I/O for any system you give a controller + 4 disks to.

 As the adapter costs a lot less money then the disk it may be a viable alternative.  
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Author Comment

by:menefre
ID: 35014824
Dear dlethe

thanks a lot for your thoughts - much appreciated!
BUT - My problem is NOT vmWare! I know how to handle vmWare. vmWare is fine and does what it says.
My RAID-CONTROLLER does not!!!
Which means, concerning your suggestion to create 6 Arrays: it's not possible!! THAT'S THE PROBLEM!!!
Please, again, forget vmWare!
My RAID-Controller is the Problem!!! You know, in the beginning, when the server boots up - "press CTRL-A to enter Controller Configuration"? There is the problem! I cannot add an Array! Why?
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LVL 47

Accepted Solution

by:
David earned 250 total points
ID: 35014866
When I looked at the online manual & specs, I didn't see ANYTHING that specified the max # of LUNs.    Have you considered that this low-end controller maxes out at 4?   Do you have any documentation that implies or states that you can create > 4 in the first place?

At some point, the new LUN configuration stops.  Exactly how deep in the process do you get before it "doesn't work"?  
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Author Comment

by:menefre
ID: 35014975
I found nowhere in the specification anything the sets the maximum numbers of arrays to 4. I've got no indication whatsoever. Nowhere in the manuals, documentations or on the website.

When I m in the ACU (the configuration utility for the Controller that comes up when pressing "CTRL-A" at bootlevel) I can create Arrays. I have to choose the available disks and then choose "create array", define everything I need (what kind of array, size,..) and then hit create. I was able to do this 4 times.
When I now want to add an another array it shows the list of available disks to choose from as empty. Those disks have been used for the other arrays, but I can have multiple arrays on a disk (according to specifications). So my questions is: why is this list empty? where are the disks?

Addon: what would be in your opinion a "good" controller?
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Author Comment

by:menefre
ID: 35015148
found the answer: http://ask.adaptec.com/scripts/adaptec_tic.cfg/php.exe/enduser/std_adp.php?p_faqid=15337

maximum number of arrays on the same diskset: 4

thanks for your thoughts.
they could have written that in the specifications on the productwebsite.....
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LVL 47

Expert Comment

by:David
ID: 35015222
wait a minute.  I told you in message #35014866 to check that it even supported more than 4 LUNs.  You took my advice, confirmed that this is a problem and didn't award points?
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LVL 47

Expert Comment

by:David
ID: 35015237
LSI controllers are certified for VMWARE and and handle a large number of drives.  But be sure to check to see that the disks are enterprise class.  You don't want to be using desktop class disks with LSI controllers.  (And if you are write intensive, consider getting one with a battery backup unit. this will make a nice improvement in write I/O
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Author Closing Comment

by:menefre
ID: 35015264
Gave the right idea - a link in addition would have been perfect. But the answers were fast and nice. thanks a lot!
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Author Comment

by:menefre
ID: 35015279
Your are absolutely right! The points are yours! sorry about that. I hope I handled it now. please feedback if am persistent in not being able to handle the reward system.

thanks a lot for your help! I will also look into LSI. All the best, menefre
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LVL 47

Expert Comment

by:David
ID: 35015312
no harm, no foul .. thanks for followup.    I emphasize make sure you use ENTERPRISE/SERVER class disks!  LSI controllers (not the AMCC/3ware, but the higher-end family that HP, IBM, DELL, Supermicro, SGI,  and just about every else with premium servers incorporate).  
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