Summary: How To Define An Apple Xserve RAID

From: Frank Everitt <>
Date: Tue Jan 18 2005 - 11:17:26 EST
The resolution isn't what I wanted to hear, but this is from Sun. This 
is a known limitation (2tb limit) on solaris 9 for LUNS that present 
themselves to format as physical luns (I.E. hardware type raid and 
certain other companies' arrays).  According to the source code which 
causes this message to print:

>> Comments:
>> from usr/src/cmd/format/ctlr_scsi.c:
>> ==============================================================
>> 2482                 /*
>> 2483                  * this requires us to use SBC-2 commands, which 
>> we
>> 2484                  * don't support
>> 2485                  */
>> 2486                 err_print("The capacity of this LUN is too 
>> large.\n");
>> 2487                 err_print("Reconfigure this LUN so that it is < 
>> 2TB.\n");
>> ==============================================================
>> this shows that the 'format' utility does not use SBC-2 (sbc stands 
>> for scsi block commands) commands.
>> therefore, we are limited to a maximum lun size of 2TB.
>> however, don't confuse this with maximum filesystem sizes.
>> by using SVM or Veritas Volume Manager, you CAN create larger devices
>> on which you CAN put larger filesystems.  however, a hardware device,
>> such as this lun that the customer is trying to configure, can only 
>> be up to 2TB in size.
>> ----------------------------------------------------------------------
>> Sun also said that this is a fairly common industry wide limit that 
>> is just now being broken. It isn't an OS limit but rather a 
>> Storage/SCSI limit. He sent the announcement below as an example.  
>> Looks like we are stuck at the 2 tb limit at this point though.  You 
>> can also get a ton more info on this if you google the keywords "2TB 
>> scsi limitation."

Sun also said that this won't be a problem with Solaris 10's zfs 
filesystem. According to Sun, you put disks and luns in pools and your 
files system will grow and shrink as needed with no intervention and no 
need to grow filesystems.  This works with everything except the OS 
filesystems. I haven't played with any version of Solaris that has zfs 
included, but will be anxiously waiting for release 10.odd_number.....

Thanks to all that replied. For the time being, I'll just need to break 
up the array into a couple of LUNs of a size less then 2TB and move on.


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Received on Tue Jan 18 11:17:56 2005

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