Re: Which RAID level?

Imagine you had 10 discs, you could stripe the first 5 and then mirror them (Raid 0+1). Or you could mirror 5 disks and then create a stripe across the mirrors (Raid 1+0).

With Raid 0+1, you could lose up to two disks (one from each stripe set) before your system would go down (assuming you have no hot swaps).

With Raid 1+0, you could lose up to six disks (one from each mirror pair) before your system would collapse.

I think this is the difference ;)

Regards,
Jason.

On Fri, 06 Aug 1999 22:24:56 GMT, cpereyra_at_ix.netcom.com wrote:

>My understanding is that Raid 0+1 (striping and mirroring) is best for
>performance and the most expensive. Raid 5 is OK but suffers from some
>performance penalty during writes. I am sure that you are going to get
>a lot of advice on this subject, so for the next person, if you know
>the answer could you explain the difference between 0+1 and 1+0? I
>know that one is preferred over the other but not sure how or why.
>
>Thanks,
>
>Carlos.
>In article <37AB0AD9.311E2E9C_at_us.oracle.com>,
> Steven Poe <spoe_at_us.oracle.com> wrote:
>> Breno,
>>
>> I don't believe it is so much the database itself, but how safe do
>you want
>> your data? RAID0 will allow you to stripe across all your drives
>with no
>> redundancy. If one drive fails, it is dead. RAID1 is a mirror of
>your
>> main drive(s). You can run, or should be able to, run RAID1 on top of
>> RAID0. RAID5 allows for rundundancy/CRC checks so if one drive dies,
>the
>> other drives keep working. I speaking from my experience with Linux,
>I
>> think NT would be the same, but I cannot assure you of that. If you
>have
>> nightly/backups, you *may not* need a mirror (RAID1) but that will
>also
>> depend on the availability of your database too. There can be
>arguments
>> for each case.
>>
>> -Steven Poe
>>
>> Breno de Avellar Gomes wrote:
>>
>> > I am about to install high availability Oracle8i FailSafe using SMP
>and
>> > RAID Compaq Servers (Intel) running NT 4.0.
>> > Some DBA advised me to use RAID level 0/1, others 5. It seems to be
>> > controversial.
>> >
>> > Wich level is more adequate? Why should I use one instead another?
>> >
>> > Thanks in advance
>> >
>> > Breno
>>
>>
>
>
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Received on Mon Aug 09 1999 - 06:08:00 CDT