[mythtv-users] OT? Shuttle + ProRAID or Obsidian case for i3/i5 Myth BE ?
travis at tabbal.net
Wed Sep 21 20:54:49 UTC 2011
On Wed, Sep 21, 2011 at 2:09 PM, linux guy <linuxguy123 at gmail.com> wrote:
> Its very interesting that you bring this up.
> Doesn't the ProRaid enclosure handle the RAID aspect entirely in hardware
> ? I understand that it will run from USB3.0 or SINGLE CHANNEL eSATA and
> thus I assume the drive(s) in it look like one big storage volume, when in
> fact they are a RAIDed storage device. That was one of the appeals of it to
> Some of the other 4 bay RAID enclosures require either 4 SATA connections
> or a multiple channel SATA card/cable. The ProRAID doesn't.
It looks like it does the RAID bit in hardware for this device. It's
probably slow, given the price point. The other downside is that should
something happen to the ProRaid, and you can't get another one for whatever
reason, your data is likely not accessible at a price you would want to pay.
> This is the MB I was intent on using.
> It has
> *Intel® H67(B3) Express Chipset*
> 2 xSATA 6.0 Gb/s ports (gray)
> 4 xSATA 3.0 Gb/s ports (blue)
> Intel Rapid Storage Technology Support RAID 0,1,5,10
> The RAID options are set in BIOS.
> That would be a totally hardware based RAID, right ?
Motherboard BIOS RAID is a "fakeRAID" in nearly every case. There are
probably a few really high end server boards that come with a real RAID
chip, but most figure their target market won't use it anyway and just leave
them lots of slots to put a RAID card in. The so called "fakeRAID" setups
have the same issue that the ProRaid/Drobo/etc. all have, if you don't get
exactly the right hardware, and in many cases, firmware revision, your data
can't be read back. Sort of defeats the purpose of RAID, no?
> RAID5 has a lot of deficiencies with respect to writing data,
>> and it's not worth the efficiency benefits until you have a lot more
>> than four drives, at which point you would be better with RAID6, or
>> something else that allows more than a single drive failure.
> I'm not sure what to say. I haven't had a HD fail in the last 10 years.
> I'm not sure why I would need a RAID setup that would tolerate multiple
> drive failures.
> What would the multiple drive failure tolerant RAID be ? RAID 1 ?
As the other post mentioned, RAID6 = 2 drives may fail without any data
loss. Multipule mirrors with a stripe over them AKA RAID10, might give you
the same type of setup, with somewhat different failure modes.
IMO, unless you have enterprise $, or just want to have an extra RAID
card/enclosure around that exactly matches what you are running, you should
stick to software RAID. Linux md devices have proven quite reliable over the
years. ZFS is another option.
Honestly, with Myth stuff, I wouldn't bother. Losing TV recordings is
annoying, but not worth the trouble of an array. And you can get I/O bound
very fast with recordings and playback in a myth system using RAID,
particularly a small RAID5 like you are talking about. Performance of the
array is about equal to a single drive, add in all the seeks you need to
keep up with and your available I/O falls off fast. Using single drives in
storage groups is a better solution, IMO. If you really must archive the TV
shows, I would use 2+ drives for recordings in a Myth SG, then copy the
recordings off to a large, slower, array later.
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