RAID 0 vs. no RAID at all

[Waldo]

Hi,

I'm trying to configure a purchase (Dell desktop) for high-end, home use.
I'd like some fault tolerance but high performance as well. I'm not
familiar with RAID levels and what they do for me.

I've gone here:
http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html to read
up on RAID 0 (and other levels). But there I read:

Fault Tolerance: None. Failure of any drive results in loss of all data,
short of specialized data recovery.

So, what's the difference between no RAID configuration at all, or RAID 0???

The configuration/pricing options for the Dell desktop are:

250GB SATA (7200RPM) Hard Drive, and
250GB SATA RAID 0 (Data Striping) [+ AUD 661.10]

I'm thinking of just ordering 2 separate 250GB hard drives, use the 2nd
drive primarily as a backup, and perform regular backups from the primary to
the secondary drive. Esp. since RAID 0 offers no fault tolerance.

So, again, what does RAID 0 do at all vs. no RAID configuration?

Thanks for any input...

 

[Will Dormann]

So, again, what does RAID 0 do at all vs. no RAID configuration?

RAID 0 has no redundancy. Its main advantage is speed over a single
drive. But if one of the drives fail, then the whole array is lost.

If you want speed plus redundancy, check into RAID 0+1 or 1+0. (The
latter is preferred). It will require a minimum of 4 drives to
implement, but gives you the benefit of both mirroring and striping.


-WD

 

[Arno Wagner]

Waldo wrote:

RAID 0 has no redundancy. Its main advantage is speed over a single
drive. But if one of the drives fail, then the whole array is lost.

If you want speed plus redundancy, check into RAID 0+1 or 1+0. (The
latter is preferred). It will require a minimum of 4 drives to
implement, but gives you the benefit of both mirroring and striping.

If this is about reading speed, RAID5 also gives some improvement,
depending on the implementation. RAID5 needs at least 3 disks.

And for redundancy with two disks you can use RAID1. Will give some
slowdown on writing and may speed-up reading if well implemented.

Personally I have all my important stuff (system, home) on RAID1 and
all other stuff either on RAID5 or on "bare" disk with a backup copy
either on another disk or other media.

The reason I use RAID1 now is that after the second reinstallation
from backup, I was just fed up. Not though thet I use Linux and
software-RAID, which is partition and not necesarily disk based.
This gives more flexobility than a hardware solution. Note also that
with hardware-RAID you often have the problem that when your
_controller_ dies, you cannot access the disks anymore unless you
manage to get the same controller (or possibly some other from
the same vendor, don't know). Therefore any good admin advises to
keep a spare controller around if you do hardware based RAID. Disks
are less critical. You can basically replaced a failed disk with
another one that is at least as large. (Careful: it has to be exact
size or more. I have e.g. Some Seagate 80GB HDDs and one Maxtor.
The maxtor is a little larger, so it could not be replaced with
one of the Seagates in a hardware-RAID.)

All in all RAID with redundancy and especially hardware
RAID makes only sense when you actually plan for failure.
With hardware-RAID that includes controller failure. With
software-RAID that includes the possibility to install the
software on another system that can also access the disks
(usually not a problem).

Arno

 

[Rod Speed]

I'm trying to configure a purchase (Dell desktop) for high-end,
home use. I'd like some fault tolerance but high performance as
well. I'm not familiar with RAID levels and what they do for me.

I've gone here:
http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html
to read up on RAID 0 (and other levels). But there I read:

Fault Tolerance: None. Failure of any drive results in
loss of all data, short of specialized data recovery.

So, what's the difference between no
RAID configuration at all, or RAID 0???

Double the risk of losing everything, because
losing a single drive loses all data on both drives.

RAID 0 is used for increased speed, in theory.

The configuration/pricing options for the Dell desktop are:

250GB SATA (7200RPM) Hard Drive, and
250GB SATA RAID 0 (Data Striping) [+ AUD 661.10]

I'm thinking of just ordering 2 separate 250GB hard drives, use the 2nd
drive primarily as a backup, and perform regular backups from the primary
to the secondary drive. Esp. since RAID 0 offers no fault tolerance.

Thats what most do. But if you lose the primary drive,
you will have lost what got changed since the last backup.
And if say the PC gets stolen etc, you lose everything.

Its generally best to also backup what you'll slash your
wrists if you lost to multiple CDRs or DVDs if you have
a significant volume of pictures and video you care about.

You can also use something like V2i Protector which
will continuously incrementally backup so that the
amount lost on a hardware failure is minimised.
You need to be running XP or 2K to run that tho.

If you are running those, you can mirror the drives at the
OS level if you are running XP or 2K and get substantial
fault tolerance that way too. BUT that doesnt protect you
against user stupidity or carelessness or a virus etc,
because both copys will have the same problem.

So, again, what does RAID 0 do at all vs. no RAID configuration?

Basically increased speed, in theory.

 

[Waldo]

Thanks Rod. I think I'll blow off the RAID 0 setup and just get the two
drives. I'll back up nightly via a scheduled job, and will look into V2i
Protector (I'm also familiar with PowerQuest's DataKeeper product). I'll be
running WXP Pro, at least until I look into W2003 further. If I lose a
day's work it won't be perfect but won't be the end of the world. It's no
backups at all that would kill me.

I'm trying to configure a purchase (Dell desktop) for high-end,
home use. I'd like some fault tolerance but high performance as
well. I'm not familiar with RAID levels and what they do for me.

I've gone here:
http://www.pcguide.com/ref/hdd/perf/raid/levels/singleLevel0-c.html
to read up on RAID 0 (and other levels). But there I read:

Fault Tolerance: None. Failure of any drive results in
loss of all data, short of specialized data recovery.

So, what's the difference between no
RAID configuration at all, or RAID 0???

Double the risk of losing everything, because
losing a single drive loses all data on both drives.

RAID 0 is used for increased speed, in theory.

The configuration/pricing options for the Dell desktop are:

250GB SATA (7200RPM) Hard Drive, and
250GB SATA RAID 0 (Data Striping) [+ AUD 661.10]

I'm thinking of just ordering 2 separate 250GB hard drives, use the 2nd
drive primarily as a backup, and perform regular backups from the primary
to the secondary drive. Esp. since RAID 0 offers no fault tolerance.

Thats what most do. But if you lose the primary drive,
you will have lost what got changed since the last backup.
And if say the PC gets stolen etc, you lose everything.

Its generally best to also backup what you'll slash your
wrists if you lost to multiple CDRs or DVDs if you have
a significant volume of pictures and video you care about.

You can also use something like V2i Protector which
will continuously incrementally backup so that the
amount lost on a hardware failure is minimised.
You need to be running XP or 2K to run that tho.

If you are running those, you can mirror the drives at the
OS level if you are running XP or 2K and get substantial
fault tolerance that way too. BUT that doesnt protect you
against user stupidity or carelessness or a virus etc,
because both copys will have the same problem.

So, again, what does RAID 0 do at all vs. no RAID configuration?

Basically increased speed, in theory.

 

[Waldo]

Oops I just remembered one more thing. Can you tell me how to accomplish
the below, or at least point me to the right application in XP?

 

[Waldo]

Sorry for the noise/spam. Disk Management -> Help -> Disk Management -> How
To... got me what I need, plus enough text strings to Google further if I
need to.

I guess my remaining decision is: two basic disks/regular
backups/PowerQuests V2i Protector vs. mirrored dynamic disks (RAID 1???)

two basic disks:
pro - will have 500GB total space available
pro - is readable from DOS (for Ghost, etc)
pro - I know I can use PartitionMagic with this setup
con - no automatic backup. must schedule regular backup or run V2i
Protector (I experienced some sluggishness when I ran DataKeeper, dunno if
V2i is similar)

mirrored dynamic disks:
pro - automatic backup, fault tolerant
con - only readable from W2K, WXP Pro, and W2003 Server. Not readable from
DOS (can't use Ghost)
con - I don't know if PartitionMagic will work with mirrored disks
con - only have 250GB total space. I have a combined 160GB on my current
systems. If I keep this system for a while I may approach 250GB, esp if I
keep creating VMware images and rip my CD's/DVD's to disk.

Ok, if you have thoughts on this list I welcome them...

 

[Rod Speed]

Oops I just remembered one more thing. Can you tell me how to
accomplish the below, or at least point me to the right application in XP?

Its part of the admin tools. Just put mirror in the help.

 

[Rod Speed]

Sorry for the noise/spam. Disk Management -> Help ->
Disk Management -> How To... got me what I need,
plus enough text strings to Google further if I need to.

I guess my remaining decision is: two basic disks/regular backups
/PowerQuests V2i Protector vs. mirrored dynamic disks (RAID 1???)

Or both.

The main difference is that mirroring is close to instantaneous
so it doesnt protect you against user stupidity stuffing things
up or stuff like a successful virus attack. The main advantage
is that its as close as practical to always being up to date.

two basic disks:
pro - will have 500GB total space available
pro - is readable from DOS (for Ghost, etc)
pro - I know I can use PartitionMagic with this setup
con - no automatic backup. must schedule regular backup
or run V2i Protector (I experienced some sluggishness
when I ran DataKeeper, dunno if V2i is similar)

Its not as bad, but that obviously depends on the system horsepower.

mirrored dynamic disks:
pro - automatic backup, fault tolerant
con - only readable from W2K, WXP Pro, and W2003
Server. Not readable from DOS (can't use Ghost)
con - I don't know if PartitionMagic will work with mirrored disks
con - only have 250GB total space.

Thats a bit superficial. In practice the main difference
space wise is that the images can be compressed,
but then you can compress dynamic disks too.

I have a combined 160GB on my current systems.
If I keep this system for a while I may approach 250GB, esp if I
keep creating VMware images and rip my CD's/DVD's to disk.

Thats one advantage with basic disks, you do have rather
more flexibility, being able to say delete the image file if
you need space temporarily and have the stuff you'll slash
your wrists if you lose on separate removeable media etc.

Ok, if you have thoughts on this list I welcome them...

One obvious approach is to just get more drive space with
hard drives so cheap and have both bulletproof mirroring and
incremental backup as well to cover the situation where you do
something rather stupid and have that automatically mirrored
and can just step back gracefully using the incremental backup.

Hard drives are now so cheap that I dont even hesitate do
buy more space when that produces operational convenience.

 

[Z Man]

XP?

Its part of the admin tools. Just put mirror in the help.

Is a RAID card necessary, or can it be done all through the software
(referring to both XP Pro and Windows 2003 Server)? Reason I ask is that I
would like to use an Adaptec 39160 with Windows 2003 Server, but the 39160
does not (as far as I can tell) support hardware RAID. What are the pros and
cons of hardware vs. software RAID?

 

[Rod Speed]

Is a RAID card necessary,
Nope.

or can it be done all through the software
(referring to both XP Pro and Windows 2003 Server)?
Yep.

Reason I ask is that I would like to use an Adaptec 39160
with Windows 2003 Server, but the 39160 does not (as far
as I can tell) support hardware RAID. What are the pros
and cons of hardware vs. software RAID?

The main advantage with hardware RAID is that the work
is offloaded to the hardware. Thats particularly desirable
with the calculation intensive RAID like RAID5

With basic mirroring, there isnt a lot of overhead involved, and
modern personal desktop systems usually have plenty of spare
horsepower anyway, so OS based mirroring is very viable.

And the other big advantage of OS based mirroring
is that its much less hardware dependant so you dont
end up in rather deep do do if the RAID hardware fails.