Amazing RAID array performance

I've just built my first striped RAID array and I can't believe how easy it
was and the terrific performance I'm getting from it.

I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133 7,200rpm)
one to replace a crashed drive and one as a spare. I thought that I'd add a
cheap Silicon Industries 0649 PCI RAID card for an extra tenner and play
with it. Easy to install, setup the striped two disk array in the BIOS, add
the driver in Windows XP and then format it as NTFS.

I tested it with Sandra and it says a bandwidth of 93MB/s! My C: drive
(80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive is completely
empty but that shows an amazing improvement over a single drive. According
to Sandra examples I should be getting 65MB/s.

Is this typical for RAID arrays? How reliable are they in reality? Do many
folks out there use them for desktops?

Jonathan Eales wrote:
> I've just built my first striped RAID array and I can't believe how easy it
> was and the terrific performance I'm getting from it.
>
> I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133 7,200rpm)
> one to replace a crashed drive and one as a spare. I thought that I'd add a
> cheap Silicon Industries 0649 PCI RAID card for an extra tenner and play
> with it. Easy to install, setup the striped two disk array in the BIOS, add
> the driver in Windows XP and then format it as NTFS.
>
> I tested it with Sandra and it says a bandwidth of 93MB/s! My C: drive
> (80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive is completely
> empty but that shows an amazing improvement over a single drive. According
> to Sandra examples I should be getting 65MB/s.
>
> Is this typical for RAID arrays? How reliable are they in reality? Do many
> folks out there use them for desktops?
>

I'm thinking about doing this myself with two SATA drives, but would I
be correct in thinking that with RAID 0 you're doubling the chance of
losing all your data, if one of the drives goes thats it, right?

I must admit I've never had a HD fail (but then I've only ever had 4 or
5!), nor do I have much important data that I don't have backed up
either (any new space I'd probably only use to install games into and
perhaps make a copy of all my CD's or something).

--
[ste]
This week, I shall be mostly eBaying these things:
http://tinyurl.com/x6fo

"Jonathan Eales" <> wrote in message
news:m7vdd.77$...
> I've just built my first striped RAID array and I can't believe how easy
> it was and the terrific performance I'm getting from it.
>
> I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133
> 7,200rpm) one to replace a crashed drive and one as a spare. I thought
> that I'd add a cheap Silicon Industries 0649 PCI RAID card for an extra
> tenner and play with it. Easy to install, setup the striped two disk
> array in the BIOS, add the driver in Windows XP and then format it as
> NTFS.
>
> I tested it with Sandra and it says a bandwidth of 93MB/s! My C: drive
> (80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive is completely
> empty but that shows an amazing improvement over a single drive.
> According to Sandra examples I should be getting 65MB/s.
>
> Is this typical for RAID arrays? How reliable are they in reality? Do
> many folks out there use them for desktops?
>
>
>

I assume you are referring to RAID0?

You may find that your actual experience will not live up to the
benchmarks - depending on your system usage.

Also, RAID0 (as opposed to RAID1) will double your chances of failure, so
it's not advisable to hold mission critical data on the array.

I tried RAID0, but found 2 single SATA drives to be about the same or
slightly faster. My data is held on a separate hard drive.
--
Doug Ramage

[Watch Spam Trap]

"Jonathan Eales" <> wrote in message
news:m7vdd.77$...
> I've just built my first striped RAID array and I can't believe how easy
> it was and the terrific performance I'm getting from it.
>
> I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133
> 7,200rpm) one to replace a crashed drive and one as a spare. I thought
> that I'd add a cheap Silicon Industries 0649 PCI RAID card for an extra
> tenner and play with it. Easy to install, setup the striped two disk
> array in the BIOS, add the driver in Windows XP and then format it as
> NTFS.
>
> I tested it with Sandra and it says a bandwidth of 93MB/s! My C: drive
> (80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive is completely
> empty but that shows an amazing improvement over a single drive.
> According to Sandra examples I should be getting 65MB/s.
>
> Is this typical for RAID arrays? How reliable are they in reality? Do
> many folks out there use them for desktops?
>
>
>
Raid 0 gives the performance increase at the cost of fault tolerance - if
either disk fails then you lose everything.
If you intend to store important files on there, then back-up regularly or
buy two more similar drives and create a Raid 0+1 if the controller supports
it. (Mirrors your raid 0 onto the two extra drives so get almost as high
performance plus improved fault tolerance) - see
http://www.acnc.com/04_01_0_1.html

Dave

logized wrote:
> "Jonathan Eales" <> wrote in message
> news:m7vdd.77$...
>> I've just built my first striped RAID array and I can't believe how
>> easy it was and the terrific performance I'm getting from it.
>>
>> I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133
>> 7,200rpm) one to replace a crashed drive and one as a spare. I
>> thought that I'd add a cheap Silicon Industries 0649 PCI RAID card
>> for an extra tenner and play with it. Easy to install, setup the
>> striped two disk array in the BIOS, add the driver in Windows XP and
>> then format it as NTFS.
>>
>> I tested it with Sandra and it says a bandwidth of 93MB/s! My C:
>> drive (80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive
>> is completely empty but that shows an amazing improvement over a
>> single drive. According to Sandra examples I should be getting
>> 65MB/s. Is this typical for RAID arrays? How reliable are they in
>> reality? Do many folks out there use them for desktops?
>>
>>
>>
> Raid 0 gives the performance increase at the cost of fault tolerance
> - if either disk fails then you lose everything.
> If you intend to store important files on there, then back-up
> regularly or buy two more similar drives and create a Raid 0+1 if the
> controller supports it. (Mirrors your raid 0 onto the two extra
> drives so get almost as high performance plus improved fault
> tolerance) - see http://www.acnc.com/04_01_0_1.html
>
> Dave

Why not just buy one more drive and do RAID 5 ?

--
Alan

"Jonathan Eales" <> wrote in message
news:m7vdd.77$...
> I've just built my first striped RAID array and I can't believe how easy
> it was and the terrific performance I'm getting from it.
[snip]
> I tested it with Sandra and it says a bandwidth of 93MB/s!
[snip]
> Is this typical for RAID arrays?

Pretty good, but throughput is only one measure of performance. General
performance is more influenced by access time, IME. RAID 0 doesn't improve
this, and may actually make it worse depending on a number of factors.

> How reliable are they in reality?

Half as reliable as a single drive, assuming no driver bugs.

> Do many folks out there use them for desktops?

Many who probably shouldn't .

Alex

The message <>
from "Alex Fraser" <> contains these words:

> "Jonathan Eales" <> wrote in message
> news:m7vdd.77$...
> > I've just built my first striped RAID array and I can't believe how easy
> > it was and the terrific performance I'm getting from it.
> [snip]
> > I tested it with Sandra and it says a bandwidth of 93MB/s!
> [snip]
> > Is this typical for RAID arrays?

> Pretty good, but throughput is only one measure of performance. General
> performance is more influenced by access time, IME. RAID 0 doesn't improve
> this, and may actually make it worse depending on a number of factors.

> > How reliable are they in reality?

> Half as reliable as a single drive, assuming no driver bugs.

> > Do many folks out there use them for desktops?

> Many who probably shouldn't .
> Alex

RAID coverage always comes down to cost in the end.
You have to decide if recovering from a disaster is worth the cost of
purchasing extra HDD's and possibly a dedicated RAID controller.
Using multiple HDD's for RAID-0 gives great performance increases, but
for every drive you add to the RAID-0, you add extra possibility
to loosing everything on your system.
RAID1 or even better RAID0+1 gives you security but has the burden of
the extra cost.
In my mind RAID-5 is the most economic whilst giving you reasonable
security from a single HDD failure.
As always it's 'swings and roundabouts', and you get what you pay for.
If you want performance "and" security, then RAID 0+1 with as many
drives as you can afford is the way to go. Few people go down this route
because of cost.
Best of luck, Phil..

"Alan" <> wrote in message
news:gYwdd.546$...
> logized wrote:
>> "Jonathan Eales" <> wrote in message
>> news:m7vdd.77$...
>>> I've just built my first striped RAID array and I can't believe how
>>> easy it was and the terrific performance I'm getting from it.
>>>
>>> I was ordering a couple of cheap 40GB hard drives (Maxtor, ATA133
>>> 7,200rpm) one to replace a crashed drive and one as a spare. I
>>> thought that I'd add a cheap Silicon Industries 0649 PCI RAID card
>>> for an extra tenner and play with it. Easy to install, setup the
>>> striped two disk array in the BIOS, add the driver in Windows XP and
>>> then format it as NTFS.
>>>
>>> I tested it with Sandra and it says a bandwidth of 93MB/s! My C:
>>> drive (80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive
>>> is completely empty but that shows an amazing improvement over a
>>> single drive. According to Sandra examples I should be getting
>>> 65MB/s. Is this typical for RAID arrays? How reliable are they in
>>> reality? Do many folks out there use them for desktops?
>>>
>>>
>>>
>> Raid 0 gives the performance increase at the cost of fault tolerance
>> - if either disk fails then you lose everything.
>> If you intend to store important files on there, then back-up
>> regularly or buy two more similar drives and create a Raid 0+1 if the
>> controller supports it. (Mirrors your raid 0 onto the two extra
>> drives so get almost as high performance plus improved fault
>> tolerance) - see http://www.acnc.com/04_01_0_1.html
>>
>> Dave
>
> Why not just buy one more drive and do RAID 5 ?
>
> --
> Alan
>
>
>
I think the controller card mentioned by the OP only supports raid 0, 1 and
0+1.
Raid 5 is a common solution used on servers which use a more complex card to
handle parity and may have non-volatile memory backup should a fault occur
before data is completely written across the drives.
Also, Raid 5 is much slower than raid 0.

Dave

Bitstring <>, from the
wonderful person Tim Auton <> said
>"Jonathan Eales" <> wrote:
>
>>I've just built my first striped RAID array and I can't believe how easy it
>>was and the terrific performance I'm getting from it.
>[snip]
>>I tested it with Sandra and it says a bandwidth of 93MB/s! My C: drive
>>(80GB Samsung 7,200) only gets 29MB/s. OK so the RAID drive is completely
>>empty but that shows an amazing improvement over a single drive. According
>>to Sandra examples I should be getting 65MB/s.
>
>Sustained transfer isn't representative of typical performance. Seek
>times are important too and you'll probably have almost no change
>there.

Actually it'll be worse. You have to wait for BOTH drives to reach the
right sector (in rotation .. track-to-track head seek should be about
the same) .. by definition this can be no better than the best one (is
in fact as bad as the worst one). So your normal 'allow half a rotation
on average' becomes rather worse than that (more like 3/4 of a rotation
on average, iirc).

--
GSV Three Minds in a Can
Outgoing Msgs are Turing Tested,and indistinguishable from human typing.

"GSV Three Minds in a Can" <> wrote in message
news:...
> Actually [seek time will] be worse. You have to wait for BOTH drives to
> reach the right sector [...] So your normal 'allow half a rotation
> on average' becomes rather worse than that (more like 3/4 of a rotation
> on average, iirc).

According to my model, for reasons I don't understand, a stripeset of N
drives gives an average of N/(N+1) of a revolution. I'd love to know why.

For 7200rpm drives, 2/3 of a revolution as opposed to 1/2 equates to ~1.4ms
extra, or around 10% on top of the random access time for a single drive.

There are two factors that are harder to put figures to that I can think of.
First, typical access patterns are likely to be "closer" than random access,
which would increase that percentage. Second, some gain is possible when
requests fit inside a stripe, decreasing the percentage (but only if the
controller is clever enough; I think there's a good chance cheaper ones
aren't).

Alex