Two questions regarding the CERC SATA1.5/6ch RAID controller

Seth Mos seth.mos at xs4all.nl
Mon May 10 11:55:01 CDT 2004


David Kinnvall wrote:
> Following up my previous message, answering the first question
> and asking/amending the second one again. See below, please.
> 
> David Kinnvall (me) wrote:
> 
> [snip]
> 
>> Now, my questions:
>> - Can the CERC SATA1.5/6ch available for the 700 handle RAID10 ?
> 
> 
> After putting additional pressure on Dell's Swedish tech support,
> the answer to the above question became "Yes". Good. Additional
> drive has been ordered.
> 
> As for the second:
> 
>> - Can I migrate the already created RAID5 array to a RAID10 array
>>   "online", without starting from scratch? If possible, what are
>>   the steps in either the BIOS screen(s) or (preferably) in afacli?
> 
> 
> Tech support could not answer this, with neither yes nor no.
> 
> The docs for the CERC SATA1.5/6ch, available (starting) at
> http://docs.us.dell.com/docs/storage/cerc/, say, and I quote:
> 
> "Online RAID Level Migration—Lets you change RAID levels without
> rebuilding your array from scratch."
> 
> followed a bit later by:
> 
> "Table 1-1. Array Migration Possibilities
> 
> Current Array Type  New Array Type
>  RAID 0              RAID 5 or 10
>  RAID 1              RAID 0 or 5 or 10
>  RAID 5              RAID 0 or 10
>  RAID 10             RAID 0 or 5"
> 
> I have RAID5 now, and want to move to RAID10 using the fourth
> disk when it arrives. According to the above table that should
> be possible, as far as I can see. So:
> 
> - Does anybody know whether it actually *is* possible?
> 
> - Does anybody know the precise command sequence in either
>   the BIOS or (preferably) in afacli to do the migration,
>   ideally also incorporating the steps needed to get the
>   new fourth drive online as part of the process?

I think it's possible, but I am reluctant to do so. Growing an existing 
raid set is something I consider OK. Changing raid levels is something else.

Cheers




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