[dba-Tech] Win2k Server and RAID

Drew Wutka dbatech at wolfwares.com
Wed Feb 11 22:47:24 CST 2004


No formatting.  It will 'regenerate' the mirror, but that should be obvious.
Nothing is 'changed' on the drive being mirrored.

In fact, I have swapped OS drives, by putting in a new drive, mirroring the
OS partition to the new drive, breaking the mirror, and then pulling the
original drive.  Pretty easy to do, and took about 20 minutes total on a 6
gig partition (with about 2 or 3 gigs used).

SCSI are better, because they have faster I/O speeds.  However, the latest
IDE are coming up to speed.  The REAL catch the WHERE you have the drives.
IDE channels are limited.  Modern IDE drives are usually going to max the
IDE channel speed.  So if you put two drives on the same IDE channel
(Master/Slave), and then put a mirrored paritition between them, you are
going to slow things down, for writing, (because it has to write to two
drives, through the same 'channel'), and see no speed increase on reading.
Put them on seperate IDE channels, and you'll get better performance.
Obviously.  SCSI drives will be faster over all.  But if you go with a RAID
5 (three drive minimum), without SCSI, it's pointless, because 2 of the 3
IDE drives would have to be on the same channel.

As for CPU usage....drop in the bucket.  Now, if your system powers off
hard, with a power failure, etc., then your machine is going to be a little
slow at boot, while it regenerates whatever drives you have.  This is VERY
easily avoided with an UPS, that shuts the machine down normally.  Other
then that particular instance, you won't see any real performance decrease
CPU wise, especially since you're getting faster I/O speeds.

A hardware raid is ALWAYS the better choice.  A hardware anything is usually
a better choice.  We are trying out a hardware spam blocker.  It's
screaming.  But that's because it's dedicated to just that.  If they built a
hardware Jet DB Engine, it would scream!  Grin.  The real advantage with a
Hardware Raid, though, is you can then use Hot-Swappable drives.  Not
something you can do with a software raid (at least not that I have heard
of.).  In a absolute 24-7 environment, there is no other choice other then a
hardware raid.  However, Hardware raids can get expensive (not too mention
hot-swapable drives!). Since the software raid is part and parcel with the
OS, it is obviously a bit more cost effective.

Personally, almost every machine that I own, or develop on, has software
raids of one sort or another.

Drew

-----Original Message-----
From: dba-tech-bounces at databaseadvisors.com
[mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of John Bartow
Sent: Wednesday, February 11, 2004 10:32 PM
To: Discussion of Hardware and Software issues
Subject: RE: [dba-Tech] Win2k Server and RAID


Drew,
Thanks for that info. I have not done software RAID and had read that when
you select the mirror drives it will want format them. That doesn't make any
sense to me if the initial drive was already formatted but then I haven't
had the oportunity to try it either.

I have always been under the impression that SCSI drives were better suited
for intensive I/O operations. But those impressions may be a bit dusty given
the advances in IDE drives oand with Serial ATA. Do you have any advice on
IDE versus SCSI drives for RAID?

Also, what's your experience of differences in I/O performance and CPU
consumption when comparing software versus hardware RAID?

John

BTW its remarkable how little relevant information I got through googling
this subject. Did I just suck at googling today or what?
:o)


> -----Original Message-----
> From: dba-tech-bounces at databaseadvisors.com
> [mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of Drew Wutka
> Sent: Wednesday, February 11, 2004 8:07 PM
> To: Discussion of Hardware and Software issues
> Subject: RE: [dba-Tech] Win2k Server and RAID
>
>
> Not correct.  You can Mirror the OS 'volume' in Windows 2000 server, using
> the software RAID.  It just can't be part of a RAID 5 volume.
>
> Go into disk management, make the main drive, and your 'second' drive
> 'Dynamic Disks'.  It will require a reboot.  Once that is done,
> simply right
> click on your root partition, and tell it to Add Mirror.
>
> Piece of cake.
>
> As for your earlier question for performance issues, you won't really see
> any performance drop, but you will get performance gain on drive access.
> Mirrored will read twice as fast, striped will write twice as
> fast, and RAID
> 5 will read and write faster.
>
> Drew
>
> -----Original Message-----
> From: dba-tech-bounces at databaseadvisors.com
> [mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of John Bartow
> Sent: Wednesday, February 11, 2004 2:03 PM
> To: Discussion of Hardware and Software issues
> Subject: RE: [dba-Tech] Win2k Server and RAID
>
>
> William,
> My understanding is that when using software RAID 1 Windows OS
> can not be on
> a mirrored drive. When using hardware RAID 1 it can. is this correct?
>
> John
>
> > -----Original Message-----
> > From: dba-tech-bounces at databaseadvisors.com
> > [mailto:dba-tech-bounces at databaseadvisors.com]On Behalf Of William
> > Hindman
> > Sent: Wednesday, February 11, 2004 1:24 PM
> > To: Discussion of Hardware and Software issues
> > Subject: Re: [dba-Tech] Win2k Server and RAID
> >
> >
> >
> > ...it takes up cpu cycles ...but if your server is primarily a
> file server
> > rather than applications oriented, the added cycles won't be noticed.
> >
> > William Hindman
> > Government is not reason, government is not persuasion,
> > government is force. It is a dangerous servant." G. Washington
> >
> > ----- Original Message -----
> > From: "John Bartow" <john at winhaven.net>
> > To: "_DBA-Tech" <dba-tech at databaseadvisors.com>
> > Sent: Wednesday, February 11, 2004 12:25 PM
> > Subject: [dba-Tech] Win2k Server and RAID
> >
> >
> > > Does configuring RAID 1 with Win2k Server without a dedicated
> RAID card
> > have
> > > any major drawbacks?
> > >
> > > TIA
> > > John
> > >
> > >
> > > _______________________________________________
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> >
> >
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>
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