Hardware vs Software IDE Raid for Desktop

[C. Morrow]

I am planning on a 4disk RAID 5 for my desktop PC. I have used the on-board
Raid 0 implementation on my Soyo Dragon+ mobo and loved the increase in
performance I got BUT I got bit when one of the drives failed and I lost
everything. (I had #$%^& IBM 75 and 60 GXP drives).

I am looking for performance increase, both reads and writes as well as data
security so now onto RAID 5. Security is a given with RAID 5 but my
question has to do with performance, in particular performance for a desktop
PC, not a server.

In researching which IDE RAID 5 controller to get, I discovered there are
hardware and software implementations. The main difference being that
hardware implementations have a coprocessor to do the checkdigit (XOR)
calculation while the software RAID uses the processor's CPU to do the
calculations.

So I would expect the software RAID to have higher CPU utilization compared
to hardware RAID. So far so good and it would seem that the harware
solution should have better performace.

BUT since this is for a desktop PC, not a server, I am not so sure that the
software RAID would have worse performance than hardware RAID. In fact, my
processor (AMD XP2100) can probably do the checkdigit calculations FASTER
than the onboard processor on a hardware RAID board. The closest I've come
to verifying this is in the review I read at tech-report.com
http://www.tech-report.com/reviews/2002q4/ideraid/index.x?pg=1 where the
Adaptec 2400A hardware RAID board came out with the worst performance, even
when compared to the software RAID Promise SX4000. In fact the Promise
SX4000 had the best RAID 5 performance in many areas.

Now I can understand in the server world, it is best to offload the RAID 5
checksum calculations so the server processor ca go and do other things.
But in the desktop PC world, where I am the only user and when I do a disk
operation, I am waiting for it to complete anyway, I do not think that
having my processor do some of the work should affect the performance that I
see. Especially since there would be few other tasks going on anyway.

So the conclusion I come to is that for desktop PC, software RAID 5 should
be an acceptable performance solution. And it certainly is cheaper.

What do you think? If you disagree, can you point me to some references
that proves the point?

cym

 

[David Arnstein]

I am planning on a 4disk RAID 5 for my desktop PC. I have used the on-board
Raid 0 implementation on my Soyo Dragon+ mobo and loved the increase in
performance I got BUT I got bit when one of the drives failed and I lost
everything. (I had #$%^& IBM 75 and 60 GXP drives).

I suggest that you use the RAID setup that you already have (had?) and
use your money to buy a backup solution instead. You say you were happy
with the speed, so why not just fix the data security problem directly?
A backup strategy can be much more secure than RAID 5. For one thing,
you can return your PC to a previous state with a good backup strategy,
if you have to.

A lot of people are using a disk drive in a box connected to the PC with
a USB2 cable as the backup medium. I haven't tried this, but it seems
like a good idea. If you buy several, you can keep one offsite (at your
place of work, perhaps?) for even more security.

 

[Eric Gisin]

Bootable software RAID 5 does not exist for Win 2K/XP. Hardware RAID 5 is
designed for server IO patterns and often does not perform well on the
desktop.

Your best bet is RAID 1+0 on inexpensive card.

| I am planning on a 4disk RAID 5 for my desktop PC. I have used the on-board
| Raid 0 implementation on my Soyo Dragon+ mobo and loved the increase in
| performance I got BUT I got bit when one of the drives failed and I lost
| everything. (I had #$%^& IBM 75 and 60 GXP drives).
|
| I am looking for performance increase, both reads and writes as well as data
| security so now onto RAID 5. Security is a given with RAID 5 but my
| question has to do with performance, in particular performance for a desktop
| PC, not a server.
|
| In researching which IDE RAID 5 controller to get, I discovered there are
| hardware and software implementations. The main difference being that
| hardware implementations have a coprocessor to do the checkdigit (XOR)
| calculation while the software RAID uses the processor's CPU to do the
| calculations.
|
| So I would expect the software RAID to have higher CPU utilization compared
| to hardware RAID. So far so good and it would seem that the harware
| solution should have better performace.
|
| BUT since this is for a desktop PC, not a server, I am not so sure that the
| software RAID would have worse performance than hardware RAID. In fact, my
| processor (AMD XP2100) can probably do the checkdigit calculations FASTER
| than the onboard processor on a hardware RAID board. The closest I've come
| to verifying this is in the review I read at tech-report.com
| http://www.tech-report.com/reviews/2002q4/ideraid/index.x?pg=1 where the
| Adaptec 2400A hardware RAID board came out with the worst performance, even
| when compared to the software RAID Promise SX4000. In fact the Promise
| SX4000 had the best RAID 5 performance in many areas.
|
| Now I can understand in the server world, it is best to offload the RAID 5
| checksum calculations so the server processor ca go and do other things.
| But in the desktop PC world, where I am the only user and when I do a disk
| operation, I am waiting for it to complete anyway, I do not think that
| having my processor do some of the work should affect the performance that I
| see. Especially since there would be few other tasks going on anyway.
|
| So the conclusion I come to is that for desktop PC, software RAID 5 should
| be an acceptable performance solution. And it certainly is cheaper.
|
| What do you think? If you disagree, can you point me to some references
| that proves the point?
|
| cym
|
|
|
|
|
|
|

 

[Dave Hau]

I suggest that you use the RAID setup that you already have (had?) and
use your money to buy a backup solution instead. You say you were happy
with the speed, so why not just fix the data security problem directly?
A backup strategy can be much more secure than RAID 5. For one thing,
you can return your PC to a previous state with a good backup strategy,
if you have to.

A lot of people are using a disk drive in a box connected to the PC with
a USB2 cable as the backup medium. I haven't tried this, but it seems
like a good idea. If you buy several, you can keep one offsite (at your
place of work, perhaps?) for even more security.

I've tried it. Works like a charm. Using a Maxtor DM9 8MB 200GB drive
in an ADS Dual Link USB2/firewire enclosure, with Ghost 2003. Highly
recommended, esp. since big IDE drives are so cheap these days.

- Dave

 

[Doo Wopper]

cym,
I don't think either of the 2 responses that you got really read your
post. Obviously you explained what you meant by "software raid" and you
also asked about advice on Raid 5, NOT RAID 0 or 1 which you stated in
your original post that you wanted to avoid.

Looks like you did your research. You want Raid 5 for security AND
performace. RAID 1 or raid 1+0 you lose 1/2 of your disk drive space so
RAID 5 looks like a good alternative if it is available.

As for the answer to your original question (which none of the other
posters bothered to answer) although I am not familiar with the product,
the Promise SX4000 looks like a good compromise based on the few online
reviews I've seen.

Let me know if you go this route and how it turns out.
The wopper.


The

 

[Eric Gisin]

Looking at the tech-report article pictures, the only possible software RAID 5
card is the SX4000. However, it has a DIMM socket so I don't think it is.
Anyone know?

Looking at the Winbench for RAID 5, all three cards rank below single disk.
For Winstone, the SX4000 matches single disk. Like I said, RAID 1+0 is his
best bet for performance.

| cym,
| I don't think either of the 2 responses that you got really read your
| post. Obviously you explained what you meant by "software raid" and you
| also asked about advice on Raid 5, NOT RAID 0 or 1 which you stated in
| your original post that you wanted to avoid.
|
| Looks like you did your research. You want Raid 5 for security AND
| performace. RAID 1 or raid 1+0 you lose 1/2 of your disk drive space so
| RAID 5 looks like a good alternative if it is available.
|
| As for the answer to your original question (which none of the other
| posters bothered to answer) although I am not familiar with the product,
| the Promise SX4000 looks like a good compromise based on the few online
| reviews I've seen.
|
| Eric Gisin wrote:
| > Bootable software RAID 5 does not exist for Win 2K/XP. Hardware RAID 5 is
| > designed for server IO patterns and often does not perform well on the
| > desktop.
| >
| > Your best bet is RAID 1+0 on inexpensive card.
| >
| > | BUT since this is for a desktop PC, not a server, I am not so sure that
the
| > | software RAID would have worse performance than hardware RAID. In fact,
my
| > | processor (AMD XP2100) can probably do the checkdigit calculations
FASTER
| > | than the onboard processor on a hardware RAID board. The closest I've
come
| > | to verifying this is in the review I read at tech-report.com
| > | http://www.tech-report.com/reviews/2002q4/ideraid/index.x?pg=1 where the
| > | Adaptec 2400A hardware RAID board came out with the worst performance,
even
| > | when compared to the software RAID Promise SX4000. In fact the Promise
| > | SX4000 had the best RAID 5 performance in many areas.
| > |