Hi guys,

I've written a short guide to the most common levels of RAID in use,
mainly so people new to computers and storage solutions can get to
grips with it. I know I would have found a guide useful a year ago when
I was new to RAID. I know there are many resources out there, but I
tried to make mine more accessible. Please let me know what you think,
and feel free to comment if you have any opinions.

RAIDers of the lost Archives:
http://www.thedaytoday.com/archives/000012.php

Thank you.

Dave

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RAID 10, or RAID 1+0 - a stripe of several small mirrors. The best, if $$$
is not a limiter.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

"Dave" <dave.hunt@gmail.com> wrote in message
news:1107540467.730997.323260@z14g2000cwz.googlegroups.com...
> Hi guys,
>
> I've written a short guide to the most common levels of RAID in use,
> mainly so people new to computers and storage solutions can get to
> grips with it. I know I would have found a guide useful a year ago when
> I was new to RAID. I know there are many resources out there, but I
> tried to make mine more accessible. Please let me know what you think,
> and feel free to comment if you have any opinions.
>
> RAIDers of the lost Archives:
> http://www.thedaytoday.com/archives/000012.php
>
> Thank you.
>
> Dave
>

[ Post a follow-up to this message ]

Another link for Google search ? 

Dave wrote:
> Hi guys,
>
> I've written a short guide to the most common levels of RAID in use,
> mainly so people new to computers and storage solutions can get to
> grips with it. I know I would have found a guide useful a year ago when
> I was new to RAID. I know there are many resources out there, but I
> tried to make mine more accessible. Please let me know what you think,
> and feel free to comment if you have any opinions.
>
> RAIDers of the lost Archives:
> http://www.thedaytoday.com/archives/000012.php
>
> Thank you.
>
> Dave
>

[ Post a follow-up to this message ]

Do you have personal experiance of RAID 10 or 1+0? I wanted to keep my
guide simple and didn't include them for that reason. They do sound
like the best of both worlds (speed and fault tolerance). Can they be
configured via software or is hardware RAID required. If software,
which?

[ Post a follow-up to this message ]

Dave wrote:
> Hi guys,
>
> I've written a short guide to the most common levels of RAID in use,
> mainly so people new to computers and storage solutions can get to
> grips with it. I know I would have found a guide useful a year ago when
> I was new to RAID. I know there are many resources out there, but I
> tried to make mine more accessible. Please let me know what you think,
> and feel free to comment if you have any opinions.

Only a couple of nits:

1.  Two-drive RAID-0 configurations are entirely possible and sensible.

2.  *Drives* do not have parity data in RAID-5 ("Each drive's parity
data is distributed to the remaining drives" is nonsense).

3.  'A stripe array that is mirrored' is a very rare RAID construct:
most 'RAID-10' implementations are a set of mirror pairs which are then
striped.

- bill

[ Post a follow-up to this message ]

Thanks. I noticed the first one, and someone else also e-mailed me
about it. Also your second point makes perfect sense - I didn't think
that through did I!? As for the last, isn't that the same thing phrased
differently? I do admit your phrasing does make it easier to
comprehend. Correct me if I'm wrong.

Also, if I was being pedantic (sorry, but it's just in my nature) I'd
point out that three 'nits' is more than a couple. ;)

I'll make adjustments to the guide tomorrow - thanks for your input.

Dave

[ Post a follow-up to this message ]

Dave wrote:
> Thanks. I noticed the first one, and someone else also e-mailed me
> about it. Also your second point makes perfect sense - I didn't think
> that through did I!? As for the last, isn't that the same thing phrased
> differently?

No.  A RAID-0 stripe which is then mirrored (to another RAID-0 stripe)
is quite different in failure (and performance after a failure)
characteristics from a set of disk mirror pairs across which data is
then striped (in a RAID-0 manner but using mirror pairs rather than
individual disks in the array).

I do admit your phrasing does make it easier to
> comprehend. Correct me if I'm wrong.
>
> Also, if I was being pedantic (sorry, but it's just in my nature) I'd
> point out that three 'nits' is more than a couple. ;)

The physical dictionary closest to my hand includes as its fourth
definition of couple "an indefinite small number; a few".  I wrote my
opening phrase with only the first two corrections in mind, but when a
third appeared did not feel the need to alter it.

- bill

[ Post a follow-up to this message ]

On 4 Feb 2005 12:30:26 -0800, "Dave" <dave.hunt@gmail.com> wrote:

>Do you have personal experiance of RAID 10 or 1+0? I wanted to keep my
>guide simple and didn't include them for that reason. They do sound
>like the best of both worlds (speed and fault tolerance). Can they be
>configured via software or is hardware RAID required. If software,
>which?

"The Best" raid is dependent on your workload and IO patterns.  Not
all workloads are optimal under raid 10.  Example would be very large
file transfers (multimedia, geological exploration, etc), they are
much better served by raid3 performance-wise if implemented properly.

But, for 95% of applications, raid 10 is "the best".

~F

[ Post a follow-up to this message ]

Thanks for your clarification bill. As for your use of 'couple', I
shall let you off - assuming you were using it informally. As an IT guy
though I prefer to be strictly correct, which is why I appreciate your
feedback.

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