[ale] Onboard RAID

[Tim Watts]

I may be out of my league here but I have to ask: Given that it's a
lightly taxed, 10 user system are you sure RAID is the right solution?
I usually think RAID for high volume, 24x7 operation systems.  If it's
for the flexibility of extending the storage space at will I thought
there was a windows equivalent of LVM out there.  My apologies if I'm
just exposing the extent of my ignorance.


On Wed, 2011-11-16 at 14:12 -0500, Greg Clifton wrote:
> Thanks Mike,
> 
> 
> More details this is a new server (Single Proc Xeon X3440) with only
> 10 users, so it won't be heavily taxed. Moving the storage to a
> different Linux box really isn't an option either. We're replacing an
> OLD server running NT with the 2008 server. 
> 
> 
> What you are saying is that SOFTWARE is "more better" in all cases
> than the BIOS based RAID configuration. OK, but does Server 2008
> support RAID 10? If not, we must rely on the BIOS RAID. If we must do
> that then the question falls back to which is the better RAID option
> [under Windows]. I saw something on some RAID forum that said the
> Adaptec was for Linux OS and the Intel for MS OS. Since Adaptec
> drivers are built into Linux, that at least makes some sense.
> 
> 
> Regards,
> Greg
> 
> On Wed, Nov 16, 2011 at 1:41 PM, Michael B. Trausch <mike at trausch.us>
> wrote:
>         
>         On 11/16/2011 01:20 PM, Greg Clifton wrote:
>         > OK folks, put down your flame throwers, but we're building a
>         Windows
>         > 2008 server w/ mirrored boot drives and 4 2TB drives for
>         data in a RAID
>         > 10 configuration for a customer. Modern motherboards give
>         you the option
>         > of running Intel Matrix RAID or Adaptec RAID in the BIOS and
>         I assume
>         > you can also run Windows total software RAID. So my question
>         for the ALE
>         > brain trust is which is the better/best option and why so
>         (and no
>         > running a Linux server is NOT an option in this case)?
>         
>         
>         Regardless of the operating system you are using, these days
>         you want to
>         use some form of pure software RAID over hardware RAID (or
>         "fakeraid",
>         that is, BIOS-provided software RAID).  The reason is that
>         software RAID
>         layouts are more portable (for example, one can use Windows
>         Dynamic
>         Disks even on Linux systems because the Linux kernel
>         understands the
>         format used on them).
>         
>         Given the power and bandwidth provided inside of today's
>         modern systems,
>         you should not see any problems with doing RAID entirely in
>         software,
>         and in the event of catastrophic failure the fact that the
>         format is
>         well-known and understood makes it easier to effect recovery
>         if ever it
>         became necessary.  (Of course, it never should, but things
>         happen in
>         this crazy world...)
>         
>         If you will always have an up-to-date backup system, then it
>         doesn't
>         matter; offload to a hardware RAID controller if you have one
>         as it will
>         save bandwidth on the computer's buses, but know that
>         recovering the
>         data from the drives may one day be impossible, and if you
>         have any
>         sizable window between successful backup run and complete
>         array failure,
>         you might well be hosed in such a situation.
>         
>         Ideally, you would separate that component out.  You can use
>         those same
>         drives in some other box.  For example, you could have a small
>         Linux box
>         that uses Linux software RAID, and simply expose the RAID
>         device to a
>         dedicated network interface via iSCSI.  Then Windows 2008 can
>         use that
>         iSCSI device for its own storage.  You get both upsides, then:
>         bandwidth
>         savings (Windows isn't worrying about issuing writes multiple
>         times, for
>         example) and a well-understood disk format for the RAID
>         array's metadata
>         and data layout.  Plus, it leaves you options for later: for
>         example,
>         you could use LVM to put two disks together, and use RAID to
>         mirror
>         that, such that now you would have the space to perform
>         block-snapshots
>         if needed, e.g., for backup purposes (which means you don't
>         have to
>         worry about using Microsoft's heavy backup program to perform
>         the backup).
>         
>                --- Mike
>         
>         
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