[olug] To RAID or not to RAID

[Christopher R. White]

I have over 500 gb of dvd rips, 10+ years of photos, thousands of hours of
music and more, nearly 1 TB total.  I'd really hate to lose it all!

I've always liked the idea of mdadm better than lvm personally, I guess I
just wanted to hear it from someone else.

Here's how I setup the system: 2x WD Black 1.5 TB drives with 4 identical
partitions each.  90 GB for root filesystem - GRUB's native mdadm RAID boot
works great btw - GRUB gets installed to both drives for redundancy, 400 GB
for /home (dvd rips in progress get stored there and I keep alot of ISOs,
VirtualBox VMs, etc hanging around) and 1 TB for /opt (where I store
optional data such as movies, pics, etc.) and the remaining roughly 5 GB is
swap space (not mirrored).  I know I'll never need that much as I have 18
gb ecc ddr2 ram but it was the leftovers on my disks, lol.

All partitions are then mirrored to each other using mdadm.  The /opt
partition was then formatted as an LVM volume in case I choose to add
another drive (or 2) down the road.  I have a single 1 TB drive now that
was holding my /opt data but the idea of no redundancy kept me up at night
- I've thought of adding it to the mix, for now it's a backup drive.  Since
it's still mirrored raid, if I lose a drive, I can easily rebuild the array
and get back to business.

All the above runs on a newly refurbished SuperMicro X7DVL-3 motherboard
with Dual Xeon E5405 CPUs.

Now to replace the old tape drive with one of these and setup a backup job
to run nightly -
http://www.newegg.com/Product/Product.aspx?Item=N82E16817998020&Tpk=N82E16817998020
and maybe also a pair of 2 TB HDDs to go with it  ^_-   I may also get a
tower case for it to give me more drive space as the rackmount case isn't
doing anybody any good sitting on the shelf.  Anybody need a 4u rackmount
case and sata tape drive (I think it takes 500 gb tapes, I'll need to look
to be sure)

I lost my media once to a faulty drive, never again!!!

On Mon, Sep 22, 2014 at 9:52 AM, Obi-Wan <obiwan at jedi.com> wrote:

> On 09/22/2014 09:31 AM, Christopher R. White wrote:
>
>> I am in the process of building a new home server.  I've finished
>> collecting all the parts and am at the put it all together stage.  This
>> will be an all-in-one home server to hold my media, photos, PC backups,
>> etc.  i want to make sure I have data redundancy factored in before I move
>> ahead.  In the past, I've always used software RAID but I'm looking at LVM
>> as an alternative.  I currently have 2 drives but the thought of adding
>> more is always in the back of my mind (hence the idea for LVM).  What is
>> your experience with LVM?  Pros, Cons, something I'm not considering?!
>>
>
> I've got somewhere north of 10TB in my desktop machine, spread across six
> drives.  One's the boot/OS disk, but the other five are a mis-matched hodge
> podge of drives that were each top of the line when I bough them over the
> past several years.
>
> Those five "data" drives hold all of the non-OS data on my system. They're
> seen by the OS as three filesystems, configured as follows:
>
> * A 1.5TB partition on each drive gets combined to create my "photo"
> filesystem.  The smallest drive is only 1.5TB, hence the choice of
> partition size.
>
> * The three larger drives each also have a 500GB partition that gets
> combined into my "home" filesystem, which contains all my personal stuff
> other than digital photos.  The next-smallest drive is 2TB, and had only
> 500GB left after the initial 1.5TB partition was carved out.
>
> * One remaining drive still had another 1TB left, which gets used by
> itself to store my DVD rips that are easily recreated if I lose that disk.
>
> For years, the two multi-disc filesystems were just concatenated together
> using LVM so that I could extend them by adding another drive to the
> system.  That worked well enough, but every time I lost a drive, I had to
> extract everything off backup, which takes a very long time for that much
> data.  When I finally filled all the drive bays in my chassis, I decided to
> give up my ability for dynamic expansion and instead use mdadm to implement
> RAID5 on the two important filesystems.  I haven't lost a drive yet under
> that setup, so I can't say how well it works, but I definitely prefer the
> thought of not having my machine go down for a couple days when a drive
> does fail.
>
> So I guess my advice to you depends on your uptime requirements and your
> backup capacity.  If you don't have very much data and you can tolerate
> being down for a while until you replace a failed drive, then just use
> LVM.  It's a lot easier to work with than mdadm, IMHO.  If you can't afford
> to be down very long and/or you have tons of data to restore, then use
> mdadm RAID on your drives.
>
> --
> *Ben "Obi-Wan" Hollingsworth* obiwan at jedi.com <mailto:obiwan at jedi.com>
> www.Jedi.com <http://www.jedi.com>
> The stuff of earth competes for the allegiance I owe only to the
> Giver of all good things, so if I stand, let me stand on the
> promise that You will pull me through. /-- Rich Mullins/
>
>
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