Data Storage - beginner, w/low cost question:

Author

beginner, w/low cost question:

news

2004-07-24, 2:45 am

I am trying to understand my options for a project that requires a lot of
low-cost storage,
but limited access. It will be a low-usage streaming video application.
The video will
not need a SLA guarantee, but I would have to find a way to recover *when*
disk(s)
crash.

I was thinking that I could use IDE RAID 1 w/o any backup mechanism...and if
2 drives crashed,
then I would have to figure out how to get the content back from the
original users. I have
no real-world experience on how often this is likely to happen...

The other idea I had was to just use IDE drives w/o any RAID. If I did this
I would need to
backup the data to tape storage, though I have NO idea how much it
costs...probably too much!

My simple thinking is that a 250Gig IDE drives is quite cheap, but I imagine
that coming
up with a solution that could have 2TB of storage (or 1TB w/RAID) would be
far more than
8 drives * ~$200(USD)

I see all of the RAID enclosures and NAS devices and know there are reasons
they are so
expensive...but I am not sure if they are the only way to go ;-)

thanks!

Bill Todd

2004-07-28, 5:45 pm

"news" <bit@bucket.com> wrote in message
news:rFmMc.18178$Wv4.14015@okepread03...
> I am trying to understand my options for a project that requires a lot of
> low-cost storage,
> but limited access. It will be a low-usage streaming video application.
> The video will
> not need a SLA guarantee, but I would have to find a way to recover *when*
> disk(s)
> crash.
>
> I was thinking that I could use IDE RAID 1 w/o any backup mechanism...and
if
> 2 drives crashed,
> then I would have to figure out how to get the content back from the
> original users. I have
> no real-world experience on how often this is likely to happen...

Unless your RAID is buggy or you let a failed disk sit for a good long time
before replacing it, probably never.

>
> The other idea I had was to just use IDE drives w/o any RAID. If I did
this
> I would need to
> backup the data to tape storage, though I have NO idea how much it
> costs...probably too much!

Why not just back it up to some additional inexpensive ATA disks?

>
> My simple thinking is that a 250Gig IDE drives is quite cheap, but I
imagine
> that coming
> up with a solution that could have 2TB of storage (or 1TB w/RAID) would be
> far more than
> 8 drives * ~$200(USD)

Not necessarily much more.

>
> I see all of the RAID enclosures and NAS devices and know there are
reasons
> they are so
> expensive...but I am not sure if they are the only way to go ;-)

They aren't. It sounds as if you might be talking about an application
that's almost purely read-only, with an occasional video file added, and
that doesn't need high levels of availability, just some means to take most
of the pain out of losing a disk. Software RAID - even RAID-5, to cut the
disk count from 8 to 5 with 250 GB disks - might be very reasonable to use,
and I think you can get a free implementation on Linux.

- bill

Ron Reaugh

2004-07-28, 5:45 pm

Ron Reaugh

2004-07-28, 5:45 pm

"Bill Todd" <billtodd@metrocast.net> wrote in message
news:bZmdnSyCuIn3Cp_cRVn-qw@metrocast.net...
>
> "news" <bit@bucket.com> wrote in message
> news:rFmMc.18178$Wv4.14015@okepread03...
of[vbcol=seagreen]
*when*[vbcol=seagreen]
mechanism...and[vbcol=seagreen]
> if
>
> Unless your RAID is buggy or you let a failed disk sit for a good long
time
> before replacing it, probably never.

Wrong, "disk crash" is more frequently SW caused or other non-disk hardware
caused so replacing quickly a failed RAID 1 member does little against the
overall likelihood of losing the data on the drive/array.

> this
>
> Why not just back it up to some additional inexpensive ATA disks?

That's the best solution along with using RAID 5.

Bill Todd

2004-07-28, 5:45 pm

"Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
news:JjyMc.317353$Gx4.314401@bgtnsc04-news.ops.worldnet.att.net...
>
> "Bill Todd" <billtodd@metrocast.net> wrote in message
> news:bZmdnSyCuIn3Cp_cRVn-qw@metrocast.net...
> of
application.[vbcol=seagreen]
> *when*
> mechanism...and
> time
>
> Wrong, "disk crash" is more frequently SW caused or other non-disk
hardware
> caused so replacing quickly a failed RAID 1 member does little against the
> overall likelihood of losing the data on the drive/array.

Don't be such a moron, Ron: what a 'disk crash' is is rather well
understood by anyone with even half a clue, and has nothing to do with
software - leaving aside the fact that from the context the poster was
clearly talking about disk hardware failures.

- bill

Ron Reaugh

2004-07-28, 5:45 pm

"Bill Todd" <billtodd@metrocast.net> wrote in message
news:gcOdnTFnVoGrWp_cRVn-iQ@metrocast.net...
>
> "Ron Reaugh" <ron-reaugh@worldnet.att.net> wrote in message
> news:JjyMc.317353$Gx4.314401@bgtnsc04-news.ops.worldnet.att.net...
lot[vbcol=seagreen]
> application.
> hardware
the[vbcol=seagreen]
>
> Don't be such a moron, Ron: what a 'disk crash' is is rather well
> understood by anyone with even half a clue, and has nothing to do with
> software

Nice try but anyone who reads this thread can spot the context and easily
see your asserions are a fraud.

>- leaving aside the fact that from the context the poster was
> clearly talking about disk hardware failures.

LIAR!

news

2004-07-28, 5:45 pm

"news" <bit@bucket.com> wrote in message
news:rFmMc.18178$Wv4.14015@okepread03...
> I am trying to understand my options for a project that requires a lot of
> low-cost storage, but limited access. It will be a low-usage streaming
video application. The video will
> not need a SLA guarantee, but I would have to find a way to recover *when*
disk(s) crash.

Thanks Bill and Ron!

I was thinking that RAID 1 was what I wanted, but after your comments, I
read up on RAID 5 and that seems a better match. From what I can tell, you
just need to be able to replace a failed drive immediately. And I assume
that multiple drive failures are (or can?) be unrecoverable??? (RAID 5 also
seems riskier as you increase the number of drives, If my prev. assumption
was correct...)

Looking at setups, it seems like a good solution is a rack mountable 4U
system
(An Antec 4U costs about 300 bucks, though I could never figure out what the
difference
between an "external" or "internal" drive bay is...do you know?)

So, let say I use 1 bay for a cdrom and 1 bay for a boot/OS drive and have
11 left over and I get a 3Ware RAID card 7506-12 (the 12 is for 12 disk
support, 700 bucks ouch)
(there is space for a full motherboard + full sized slots for expansion
cards)

Would the max this computer could hold is 10 * 250Gig drives + the Parity
drive?
That would be 2.5TB, can a Linux computer and that 3Ware card handle it?
(I couldn't even afford this, but I *like* thinking about how big things can
get ;-)

Would a computer like this be so busy that all it should do is be a disk
drive, or
could it also run another program (ie streaming, but a more common example
would
be Oracle or some other DB...)

Without having any real-world experience in this area, it is very difficult
to read
companie's marketing material and make sense of things ;-)

ANTEC RACK : 4U22ATX550EPS
4U EPS12V rackmount
Features:
a.. 4U rackmount chassis
b.. 550 Watt EPS12V Power supply
c.. Motherboards ATX Motherboards (up to 12" x 13")
d.. Drive Bays: 3 x 5.25, 3 x 3.5"(External) 7 x 3.5" (Internal)
e.. User configurable for 6x5.25" + 3x3.5" (External),
3x3.5"(Internal) drive bays w/out 120mm intake Fan
f.. 7 expansion slots
g.. 1 x 120mm ball bearing fan intake, 2 x 80mm ball bearing fans
exhaust
h.. 2 Front USB ports

Ron Reaugh

2004-07-28, 5:45 pm

"news" <bit@bucket.com> wrote in message
news:wGGMc.19627$Wv4.3059@okepread03...
> "news" <bit@bucket.com> wrote in message
> news:rFmMc.18178$Wv4.14015@okepread03...
of[vbcol=seagreen]
> video application. The video will
*when*[vbcol=seagreen]
> disk(s) crash.
>
> Thanks Bill and Ron!
>
> I was thinking that RAID 1 was what I wanted, but after your comments, I
> read up on RAID 5 and that seems a better match. From what I can tell,
you
> just need to be able to replace a failed drive immediately.

That's better and many RAID 5 implementations allow for a hot spare so that
the replacement happens automatically but not instantly(rebuild time). For
video, although no data is lost for a single drive failure, the
performance is degraded such that video streaming might not be feasible
until the replacement drive is up to speed.

> And I assume
> that multiple drive failures are (or can?) be unrecoverable???

Right but VERY unlikely. Other failures are much more likely than a dual
drive failure with one day.

> (RAID 5 also
> seems riskier as you increase the number of drives, If my prev. assumption
> was correct...)

A little.

> Looking at setups, it seems like a good solution is a rack mountable 4U
> system
> (An Antec 4U costs about 300 bucks, though I could never figure out what
the
> difference
> between an "external" or "internal" drive bay is...do you know?)

Tray removeable vs not.

> So, let say I use 1 bay for a cdrom and 1 bay for a boot/OS drive and
have
> 11 left over and I get a 3Ware RAID card 7506-12 (the 12 is for 12 disk
> support, 700 bucks ouch)
> (there is space for a full motherboard + full sized slots for expansion
> cards)
>
> Would the max this computer could hold is 10 * 250Gig drives + the Parity
> drive?
> That would be 2.5TB, can a Linux computer and that 3Ware card handle it?
> (I couldn't even afford this, but I *like* thinking about how big things
can
> get ;-)

I don't speak linus<g>

> Would a computer like this be so busy that all it should do is be a disk
> drive, or
> could it also run another program (ie streaming, but a more common example
> would
> be Oracle or some other DB...)

Not concurrent DB access on the video streaming HDs.

> Without having any real-world experience in this area, it is very
difficult
> to read
> companie's marketing material and make sense of things ;-)
>
>
> ANTEC RACK : 4U22ATX550EPS
> 4U EPS12V rackmount
> Features:
> a.. 4U rackmount chassis
> b.. 550 Watt EPS12V Power supply
> c.. Motherboards ATX Motherboards (up to 12" x 13")
> d.. Drive Bays: 3 x 5.25, 3 x 3.5"(External) 7 x 3.5" (Internal)
> e.. User configurable for 6x5.25" + 3x3.5" (External),
> 3x3.5"(Internal) drive bays w/out 120mm intake Fan
> f.. 7 expansion slots
> g.. 1 x 120mm ball bearing fan intake, 2 x 80mm ball bearing fans
> exhaust
> h.. 2 Front USB ports
>
>
>
>
>
>
>
>
>
>
>
>
>

Nik Simpson

2004-07-28, 5:45 pm

news wrote:
> ANTEC RACK : 4U22ATX550EPS
> 4U EPS12V rackmount
> Features:
> a.. 4U rackmount chassis
> b.. 550 Watt EPS12V Power supply
> c.. Motherboards ATX Motherboards (up to 12" x 13")
> d.. Drive Bays: 3 x 5.25, 3 x 3.5"(External) 7 x 3.5"
> (Internal) e.. User configurable for 6x5.25" + 3x3.5"
> (External), 3x3.5"(Internal) drive bays w/out 120mm intake Fan
> f.. 7 expansion slots
> g.. 1 x 120mm ball bearing fan intake, 2 x 80mm ball bearing
> fans exhaust
> h.. 2 Front USB ports

There are a lot of chassis that are much better suited to this type of
application because all the drive bays are front accessible & removable/hot
swap. Also you are neglecting the most likely failure mode by selecting a
chassis with only a single power supply. I'd suggest taking a look at
something more like:

http://www.rackmountmart.com/rm4u/rm4004.htm

It's more epxensive, but then its designed for the type of application you
have in mind and supports the basic reliability features like all hot plug
drives (twelve bays) and hot plut power supplies. If price is a factor, then
perhaps:

http://www.rackmountmart.com/rm2u/rm2008.htm

Would be a better solution, it's only 2U but still holds eight hot swap
drives and supports hot swap power for about $100 more than the 4U chassis
you've specced.

And don't forget to put the whole thing on a UPS.

--
Nik Simpson