[K12OSN] Two SATA mirrors

William Fragakis william at fragakis.com
Wed Sep 9 18:59:37 UTC 2009

RAID 1 has several other advantages:
1) Faster reads than with one device. 
2) If you do have a problem, you typically can transparently run on a
degraded RAID until you can replace the failed drive.

3) You aren't as likely to have to tell someone that you lost that
important document they spent hours on yesterday but you do have the
short memo they did the day before.

Software RAID, especially for /home, is pretty darned easy in Linux.
It's only slightly more difficult to make both disks bootable as you
have to remember to install GRUB on each one. There's really no reason
not to do it, especially with hard drives only costing $40-50 in the
sizes you are using.

There's nothing wrong with being paranoid. That's why I rsync my RAID to
yet another drive each night. (And really important stuff should go off
site every night)


On Wed, 2009-09-09 at 12:00 -0400, k12osn-request at redhat.com wrote:
> Message: 4
> Date: Tue, 08 Sep 2009 16:17:10 -0500
> From: Les Mikesell <lesmikesell at gmail.com>
> Subject: Re: [K12OSN] Two SATA mirrors
> To: "Support list for open source software in schools."
>         <k12osn at redhat.com>
> Message-ID: <4AA6C9D6.3060308 at gmail.com>
> Content-Type: text/plain; charset=windows-1252; format=flowed
> roger wrote:
> > On Tue, Sep 8, 2009 at 12:43 PM, Henry
> Hartley<henryhartley at westat.com> wrote:
> >> Since funds are a little tight Im tempted to go with your second
> option 
> >> Linux based software RAID. Am I right in assuming that as long as I
> have
> >> enough SATA connecters I should have all the hardware I need for
> that? I
> >> think I need to do a bit more research before I move forward. Do
> you know of
> >> good (and relatively recent) resources explaining how software RAID
> is done?
> >>
> > 
> > I went a slightly different approach for my home box.  I went with 2
> > 500G sata, use one for storage, then rsync it in the middle of the
> > night.  I was paranoid how easy it would be to take the disks out of
> > that box and throw them in something else if this system dies.  At
> > worst, I lose something that's not synced yet.   Of course, I could
> > cron the sync job to be every 5 minutes or so.
> Software raid is just as easy to move as a single drive - in fact if
> you 
> move a single drive both copies will still work.   The rsync copy
> does 
> have the advantage of possibly surviving some types of disasters that 
> would crash the system before being copied, though.
> -- 
>    Les Mikesell
>     lesmikesell at gmail.com

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