"Isaac Wingfield" wrote in message
...
I'm a Mac user; have been for fifteen years. I've been given a *lot* of
disks over the years by Windows users who told me the disk was no good,
that they'd tried every trick they knew, reformatting, and on and on,
but they couldn't get it to work. These are SCSI disks, BTW. I get them
by saying my kid likes to take them apart to get the magnets.

In almost every case, I stuck them on a Mac, formatted them up and
verified the media, and used them for years without a problem. I have a
very robust backup system in place, and use it constantly, but I've
never needed to use it to recover from one of those disks failing,
bacause none ever has. I've taken them out of service because my storage
needs outgrew them; the first ones I got that way were 212 Meg jobbies;
very expensive at the time.

I recently bought four 50 Gig Segate drives at a parking lot sale for
$1.00 each; all four had stickers saying "won't boot", or "BIOS Failure"
or something similar. All four work just fine on my Macs; two of them
serve my MP3s.

I'm not sure what's going on, but I sure do appreciate all the "free"
disks.

In twenty years of using computers (mostly Macs) with hard drives, I
have experienced exactly two "hard" drive failures.

I'm glad you like Macs, but I often "fix" hard drives for people who don't
know how to do it, using a PC. Nothing new there.
Another reason why SCSI drives are discarded of course is that most IBM
users don't even now what they are. They have no idea how to boot from one,
so naturally they get the error messages you refer to. No need for a Mac
though.

Like you, I have had very few hard drive failures in over 20 years, and
countless drives. But it does happen, and I try to steer clear of the models
with a bad reputation.
There was a reason the old Conner models were scorned, and an IBM was
christened "deathstar" for example. :-)

MrT.

"Tim Martin" wrote in message

"Arny Krueger" wrote in message
...

Not really. It tells me that the RAID controller or
software wan't designed for the real world.

RAIDs were coming into use when PC server drives had
MTBF's in the region of 50,000 hours.

These days, I suspect hard drive errors are not the
commonest cause of data loss ... I suspect it's human
error, followed by theft of the entire computer! And so
RAID probably doesn't eliminate the need for other
backups.

If it wasn't for viruses, spyware, fans and hard drives, my
PC business would be really slow.

I see more failed hard drives than ever.

"Richard Crowley" wrote in message

"Stéphane Guillard" wrote ...
Fine. Now tell us what brilliant scheme those persons
have come up with, in terms of "and what if the harddisk
fails ?" (which is bound to happen sooner than later,
given a harddisk merely survives a few years these days,
if not DOA), given that of course there is no smart way
to backup a 250 GB HD ?

I am researching RAID-5 based file server appliances for
my home network. There is no way to keep drives from
failing, but RAID 5 (for example) will prevent permenant
loss of data from any single drive failure. This is the
same method used in industry for decades, only now
becoming attractive for home use.

Data striping provides a very respectible bang for a lot
less bucks.

A lot of commodity motherboards come with two-drive RAID
built right in. I'm talking $50 motherboards.

"Richard Crowley" wrote in message

"Harry Lavo" wrote ...
"Richard Crowley" wrote ...
I am researching RAID-5 based file server appliances
for my home network. There is no way to keep drives
from failing, but RAID 5 (for example) will prevent
permenant loss of data from any single drive failure.
This is the same method used in industry for decades,
only now becoming attractive for home use.

You can do the same thing much simpler and for less money
with a RAID 1 two disk array (it's called mirroring). It
has also been used for years...mostly by companies
not wishing to spend the money on a RAID 5. And it is
equally effective. Once kept an entire 22 unit medical
clinic up and running for three years with no downtime
using mirrored Novell servers, two uninteruptable
UPS's, and a backup generator.

My calculations showed that it would be cheaper (and
quieter and lower power) to use RAID 5. Because I need
something like 2TB and I'd rather not have to keep 4TB
spinning to store 2TB. RAID 5 overhead is only 20-25%
while RAID1 is 100%. Or do I have my RAID definitions
confused?

Given the size of the functional array that you desire, this
looks like a pretty good application for RAID-5.

The big disadvantage of higher orders of RAID (more than two
drives) is that the controllers cost more than the drives.
IOW, you can mirror a drive these days for the price of the
second drive, about $100. But, if you want more space than
you can find on just one or two drives, then the higher
order RAID controllers start being cost-justified. I think
your application is over that line.

http://www.newegg.com/Product/Produc...ntroller+Cards

8 channels for under $200! However, its device-driver based
so heavy I/O could affect the host PC.

I remember as a very young child seeing a guy on the
Ed Sullivan show who had the whole stage full of
china plates spinning on the end of tall rods. Likely
nobody else here remembers ever seeing such a
spectacle.

Really? ;-) I think I was in college at the time.

"Arny Krueger" wrote in message
...
"Richard Crowley" wrote in message

"Harry Lavo" wrote ...
"Richard Crowley" wrote ...
I am researching RAID-5 based file server appliances
for my home network. There is no way to keep drives
from failing, but RAID 5 (for example) will prevent
permenant loss of data from any single drive failure. This is the same
method used in industry for decades,
only now becoming attractive for home use.

You can do the same thing much simpler and for less money
with a RAID 1 two disk array (it's called mirroring). It has also been
used for years...mostly by companies
not wishing to spend the money on a RAID 5. And it is
equally effective. Once kept an entire 22 unit medical
clinic up and running for three years with no downtime
using mirrored Novell servers, two uninteruptable
UPS's, and a backup generator.

My calculations showed that it would be cheaper (and
quieter and lower power) to use RAID 5. Because I need
something like 2TB and I'd rather not have to keep 4TB
spinning to store 2TB. RAID 5 overhead is only 20-25%
while RAID1 is 100%. Or do I have my RAID definitions confused?

Given the size of the functional array that you desire, this looks like a
pretty good application for RAID-5.

The big disadvantage of higher orders of RAID (more than two drives) is
that the controllers cost more than the drives. IOW, you can mirror a
drive these days for the price of the second drive, about $100. But, if
you want more space than you can find on just one or two drives, then the
higher order RAID controllers start being cost-justified. I think your
application is over that line.


I agree with Arny on this....I had no idea you were looking for so much
storage capacity. In your case, RAID 5 makes sense.

Isaac Wingfield wrote:
In article ,
"Tim Martin" wrote:

"Arny Krueger" wrote in message
...

Not really. It tells me that the RAID controller or software
wan't designed for the real world.

RAIDs were coming into use when PC server drives had MTBF's in the region of
50,000 hours.

These days, almost any disk you can buy will have an MTBF above a
million hours. But there's another "use by" date you have to pay
attention to: the useful life. That's *not* the same as the MTBF, and is
usually on the order of five years.

Taken together, what they mean is, if you buy a whole bunch of disks
(can't do statistical analysis on just one), then for the first five
years of use, they will show statistical reliability figures in the 10^6
hour MTBF range. When they are more than five years old, the failure
rates will begin to rise due to wear-out.

Do these figures assume five years of always-on use, or simply five
years since first-on? I don't leave my external drive on 24/7.


--

-S

"Steven Sullivan" wrote in message
...
Do these figures assume five years of always-on use, or simply five
years since first-on?

5 years from manufacture.

I don't leave my external drive on 24/7.

Doesn't matter, the number of power on cycles is also a consideration. And
there are other factors that even affect an unused drive.
If you were only to power up a drive say once a month, it would probably
last longer than one on 24/7, but neither will last forever, and the former
could still fail before the latter.

MrT.

Richard Crowley wrote:
My calculations showed that it would be cheaper (and quieter
and lower power) to use RAID 5. Because I need something
like 2TB and I'd rather not have to keep 4TB spinning to store

For this size array you really only have two reasonable choices.

First, is JBOD (Just a Big Old Disk). This is the most inexpensive as
you can use the OS or other software to either combine all drives into
a virtual drive or just have for example four 500GB drives.

The second as you have found is RAID5. Only one extra drive is
required. Five 500GB drives will give you 2TB usable. Or eight 250GB
drive gives 1.75TB.

The most inexpensive way to get RAID5 is a hardware controller card. I
use a RAIDCore/Broadcom BC4852 with eight 250GB drives. It's blazing
fast. Transfer rates become limited to the PCI bus speed. Using a
server motherboard you can get well in excess of 120MB per second. I
have a standard PC motherboard and get roughly 100MB per second.

Another option is a dedicated external RAID box (connected via
SATA,USB,Firewire, or ethernet). I ordered a 5-bay chassis (~$1000)
and five 500GB drives (~$1600). It hasn't arrived yet so I don't know
how it will perform.

I have high hopes for the external box since it's much easier and
cleaner than stuffing a bunch of drives in a computer case. I don't
have to get a big power supply or worry about cooling.

More info on the external box he
http://forums.storagereview.net/inde...howtopic=20784

"Rusty B." wrote ...
Richard Crowley wrote:
My calculations showed that it would be cheaper (and quieter
and lower power) to use RAID 5. Because I need something
like 2TB and I'd rather not have to keep 4TB spinning to store

For this size array you really only have two reasonable choices.

First, is JBOD (Just a Big Old Disk). This is the most inexpensive as
you can use the OS or other software to either combine all drives into
a virtual drive or just have for example four 500GB drives.

JBOD (Just a Bunch Of Discs) is what I am using now,
and I have lost 500GB of data. That is why I am looking
at RAID to provide recovery from loss of a disc drive.

The NAS unit I'm considering is from these people:
http://www.infrant.com/

The NAS unit I'm considering is from these people:
http://www.infrant.com/

I do video and affordable NAS devices are too slow. The Infrant
products look nice but only four drives. With RAID5 that means only
1.5TB useable storage with four 500GB drives.

The ReadyNAS 1TB system (750GB useable) looks to be around $1200. So
something like the NitroAV box has $200 premium but would allow you
to get a full 2TB useable, connects via SATA, USB or Firewire (i.e. no
driver or network issues). In terms of GB/$ the NitroAV is less
expensive.

If you really want space that BC4852 controller allows spanning...you
can connect up to 32 drives. 16TB anyone?