Re: Raid 0+1 or Raid 1+0

RAID 1+0 is indeed better for the reasons you stated.

It does not however equate to SAME. For instance, we have multiple RAID 10 volumes on are SAP system, but it is not SAME. Jared

On Thursday 22 May 2003 01:06, George.Leonard_at_za.didata.com wrote:
> Hi all
>
> Some documents I read says use RAID 0 + 1 but then if you look at what
> happens when a single drive fails you switch over to the other side of the
> raid, thus you can only tolerate 1 drive failure before a second drive
> failure brings the storage system down,
>
> Raid 0 + 1 = Stripe + Mirror which equates to Oracle SAME methodology
>
> Whereas
>
> Using Raid 1 + 0 gives the same performance but you can handle multiple
> drive failures.
>
> Views and comments please.
>
> George
> ________________________________________________
> George Leonard
> Oracle Database Administrator
> Dimension Data (Pty) Ltd
> (Reg. No. 1987/006597/07)
> Cell: (+27) 82 655 2466
> Tel: (+27 11) 575 0573
> Fax: (+27 11) 576 0573
> E-mail:george.leonard_at_za.didata.com
> Web: http://www.didata.co.za
>
> You Have The Obligation to Inform One Honestly of the risk, And As a Person
> You Are Committed to Educate Yourself to the Total Risk In Any Activity!
> Once Informed & Totally Aware of the Risk, Every Fool Has the Right to Kill
> or Injure Themselves as They See Fit!
>
> -----Original Message-----
> Sent: 22 May 2003 08:32 AM
> To: Multiple recipients of list ORACLE-L
>
> Hi all
> here is a question
>
>
> Q. You need to determine the amount of space currently used in each
> tablespace.
> You can retrieve this information in a single SQL statment using only one
> DBA view in the FROM clause providing you use either the _______ or _______
> DBA view.
>
> A.DBA_EXTENTS.
>
> B.DBA_SEGMENTS.
>
> C.DBA_DATA_FILES.
>
> D.DBA_TABLESPACES.
>
> I was thinking that dba_extents and dba_segments would be the correct
> answer because i could use :
> select tablespace_name, sum(bytes) from dba_extents group by
> tablespace_name ;
>
> select tablespace_name, sum(bytes) from dba_segments group by
> tablespace_name;
>
>
>
> But The answer given says dba_extents and dba_data_files. Is the given
> answer wrong or is there some way of finding out from dba_data_files how
> much space is used up in a tablespace
>
> For that matter what does the question want to know ? does it want to know
> how much space do the tablespaces have ( that would be the sum of the sizes
> of the data files ) or how much is ""used up"" ?

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Author: Jared Still
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