Re: Veritas's implementation/interpretation of RAID 0+1 and RAID 10

In comp.unix.solaris Chuck Swiger <chuck_at_codefab.com> wrote:
> In comp.sys.sun.admin Darren Dunham <ddunham_at_redwood.taos.com> wrote:
>> In comp.unix.solaris NetComrade <andreyNSPAM_at_bookexchange.net> wrote:

>>> The way it's supposed to be:
>>> http://www.acnc.com/04_01_0p1.html

>> Why would the applications between 1+0 and 0+1 be different?

> Define '+' as mirroring, and '*' as striping:
> (a+b) * (c+d) is a stripe on mirrored disks, or RAID-1,0.
> [snip..]

I was referring the web pages posted in the thread. It listed possible applications for 0+1 and 1+0, but they were different lists.

Regardless of the different failure performance of 0+1 and 1+0, the data remains in the same position on the platters. I've never noticed any performance differences between the two, so I was questioning why the different lists of applications.

To me the decision between the two layouts has to do with the amount of data, the complexity of dealing with the layout administratively, the availability of the software to handle it, and the likelyhood that I will have to deal with disk failures on the volume. I can't think of an application (read "performance") reason to use one over the other.

> and B ~= D. DiskSuite is supposed to be smart enough so it will use B in
> place of D in order to keep the filesystem available, thus giving it the same
> failure probabilities as the 1,0 case.

Right. Although the setup makes it appear to be 0+1, it's really doing 1+0 under the covers.

-- 
Darren Dunham                                           ddunham_at_taos.com
Unix System Administrator                    Taos - The SysAdmin Company
Got some Dr Pepper?                           San Francisco, CA bay area
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