What raid do I need?

  • Thread starter Thread starter Michael C
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Michael C

I want to raid a system so that 2 drives store the exact same data, so a
pair of 80gigs would come out to a capacity of 80gig, not 160. Is that raid
1?

Thanks,
Michael
 
Michael C said:
I want to raid a system so that 2 drives store the exact same data, so a
pair of 80gigs would come out to a capacity of 80gig, not 160. Is that raid
1?

Thanks,
Michael
Click to expand...

yes.
 
dylan said:
yes.
Click to expand...

Thanks guys, good guess on my part :-) I guess I can do this with a fairly
low end raid board? Any tips for using it? I was thinking of having three
drives in the machine, 1 for the OS and 2 raided for the data. That way if
there's a problem with the machine it will be easier to shift the drives to
another machine or if I need to reformat the OS it will be easier. Does that
all sound like a reasonable setup?

Michael
 
Thanks guys, good guess on my part :-) I guess I can do this with a fairly
low end raid board?
Click to expand...

Yes, just about any low-end, even the $15 ATA133 like a
Silicon Image based type you'd find on
http://www.pricewatch.com , will do a RAID1 fine.

Any tips for using it?
Click to expand...

It's pretty straight forward... jumper drives as you
normally would without a RAID card, then define the array in
the controller bios and from that point on it's just treated
same as you would a single drive, except you have the
management tools (software) that comes with it to provide
feedback on the statis and provide some features like an
automated or on-demand rebuild should a member drop out of
the array (for any reason, even powering off and unplugging
one of the drives and replacing it so you had an offline
backup of it).

I was thinking of having three
drives in the machine, 1 for the OS and 2 raided for the data. That way if
there's a problem with the machine it will be easier to shift the drives to
another machine or if I need to reformat the OS it will be easier. Does that
all sound like a reasonable setup?
Click to expand...

That will work fine. If the card you buy doesn't have the
newest bios available yet, you might consider upgrading it
first, before creating the array. If the budget allows, you
might even consider buying a 2nd, identical card (and
likewise updating it's bios) in the outside chance the card
might fail, or if it would be useful to have a 2nd system
already set up with the card operational. The information
about the array members (drives) is stored on the drives
themselves, so as long as you had the same chipset (based
cards, and sometimes the same or similar raid bios version)
you can move the array to the other card/system too.
 
kony said:
That will work fine. If the card you buy doesn't have the
newest bios available yet, you might consider upgrading it
first, before creating the array. If the budget allows, you
might even consider buying a 2nd, identical card (and
likewise updating it's bios) in the outside chance the card
might fail, or if it would be useful to have a 2nd system
already set up with the card operational. The information
about the array members (drives) is stored on the drives
themselves, so as long as you had the same chipset (based
cards, and sometimes the same or similar raid bios version)
you can move the array to the other card/system too.
Click to expand...

So if the 2 drives are identical will 1 of them be able to be removed and
put into a standard non-raid machine on it's own?
 
So if the 2 drives are identical will 1 of them be able to be removed and
put into a standard non-raid machine on it's own?
Click to expand...

It is possible to do it, likely but I don't recall the
potential variables involved. One that comes to mind is
where the metadata (array details) are stored on the drive,
at the beginning or end. With all the software RAID cards
I've used it was at the end, AFAIK. Expecting it to work
though, is not reall a safe plan so I'd recommend trying it
prior to any emergency situation to determine if it works
with (whatever the card you choose, creates).
 
kony said:
It is possible to do it, likely but I don't recall the
potential variables involved. One that comes to mind is
where the metadata (array details) are stored on the drive,
at the beginning or end. With all the software RAID cards
I've used it was at the end, AFAIK. Expecting it to work
though, is not reall a safe plan so I'd recommend trying it
prior to any emergency situation to determine if it works
with (whatever the card you choose, creates).
Click to expand...

Thanks kony, that's all useful info. I'm not really planning on moving the
drive just need to take it into consideration. One of the reasons for having
the OS on a seperate drive was so that it would be easy to put the drive
into another machine but if that's not possible then it's not possible. What
do you think of raid cards built into the motherboard? It seems it might
make it more difficult to transfer the drive to another machine unless it
has the same board

Michael
 
Thanks kony, that's all useful info. I'm not really planning on moving the
drive just need to take it into consideration. One of the reasons for having
the OS on a seperate drive was so that it would be easy to put the drive
into another machine but if that's not possible then it's not possible. What
do you think of raid cards built into the motherboard? It seems it might
make it more difficult to transfer the drive to another machine unless it
has the same board
Click to expand...

It is possible, sometimes, to get PCI RAID cards with same
chipset used on the motherboard. For example a Promise
ATA133 FastTrack (X2?) as a chip on a board is just a "lite"
bios version of the regular Promise PCI card, and within the
same bios era, drives from a lite bios can work fine from
regular PCI card.

More often these days there are southbridge-integrated RAID,
and typically they'd require another motherboard with same
chipset and (possibly) same motherbaord bios' Raid bios
integrated into it.

In short, yes it's a lot easier to deal with failures with
the separate card, or two of them. I always buy cards in
pairs myself, tend to use onboard raid as just another
(single-span) drive controller instead of RAIDing any drives
attached... though I seldom try to put many drives in boxes
at home after I'd converted a fileserver to GbE.
 
Yes, just about any low-end, even the $15 ATA133 like a
Silicon Image based type you'd find on
http://www.pricewatch.com , will do a RAID1 fine.
Click to expand...

I can't find anything.
It's pretty straight forward... jumper drives as you
normally would without a RAID card, then define the array in
the controller bios and from that point on it's just treated
same as you would a single drive, except you have the
management tools (software) that comes with it to provide
feedback on the statis and provide some features like an
automated or on-demand rebuild should a member drop out of
the array (for any reason, even powering off and unplugging
one of the drives and replacing it so you had an offline
backup of it).
Click to expand...

I am still looking for a RAID 1 board where the software will schedule
periodic backups. A backup is a mirror that has been deliberately
stopped until the next backup. That way, if the primary drive becomes
corrupted, you can swap the uncorrupted backup.

That Enermax DynaBacker seemed like it was the solution because its
s/w supported scheduled periodic backups. But I had to send it back
because it was not working properly and the company in the US
(EnermaxUSA) and the company in Taiwan (Enermax) would not support it.
They would not even furnish an extra tray that worked. I found out
from Directron where I bought it that it is likely to be recalled. The
actual manufacturer is ETrunk in Taiwan and they no longer have a
website. Something is obviously wrong here, so Directron advised me to
return it for a full refund before I got stuck with it. Directron then
dropped it from their offering. Too bad, because it had a lot going
for it.

You would think that writing a Backup application using a controller
board would be simple enough. I believe there is a sufficienty large
market for hardware backup. RAID 1 is a bit overkill considering that
modern drives are so reliable. The real need is for backup because it
is easy enough to corrupt a boot drive with bad installations,
viruses, etc. At worst you are only a short period of time behind if
you have to replace with the backup - assuming you backup often.


--

Greatest Movie Line Ever
http://home.houston.rr.com/rkba/MovieLine.wmv

"What is history but the story of how politicians have
squandered the blood and treasure of the human race?"
--Thomas Sowell
 
I can't find anything.
Click to expand...

On main pricewatch page, choose
"Cards -Controller", "ATA133" (or) "ATA RAID", but there
will be some cards in the wrong category, like SATA cards
that you'll have to ignore.

or, the 'egg has one or more,
http://www.newegg.com/Product/Product.asp?Item=N82E16815124001
but that's an ATA133- only card, there are now a few that
sacrifice one of the ATA133 channels for a couple of SATA150
ports instead... depending on what you wanted, but just like
regular ATA133 channels, even if you only wanted one pair of
drives you'd be better off putting each on it's own ATA133
channel. IF you have a huge chassis and need to use an
extra-long (>18") ATA cable, I suggest using ATA100 instead
of ATA133 as you are exceeding the cable length spec, ATA100
is slower in transfer and may help there but in use the
drives internal throughput is more of a bottleneck than
ATA100 vs 133.
I am still looking for a RAID 1 board where the software will schedule
periodic backups. A backup is a mirror that has been deliberately
stopped until the next backup. That way, if the primary drive becomes
corrupted, you can swap the uncorrupted backup.
Click to expand...

i dont' know that it will have a lot to do with which RAID1
card you chose, as you'd be looking at logically disabling
the drive access through windows, and/or physically
disconnecting power to it, IF you want it powered off too.
Neither of these aspects depend on which card you had
installed. Why would you expect the primary AND backup
drive to be corrupt simultaneously if backup wasn't
disabled? Virus? I suggest looking more at actual virus
trends if that's the case, focusing on real world observed
exploits to determine if this is a valid concern/risk.
Personally I do the RAID1 backup then have an offline
drive/system that manually backs up the online version.

You would think that writing a Backup application using a controller
board would be simple enough. I believe there is a sufficienty large
market for hardware backup. RAID 1 is a bit overkill considering that
modern drives are so reliable.
Click to expand...

They're reliable until they fail, and all drives eventually
do. Backups are for that eventual failure... if there is a
real daily risk to data it's about security rather than
drive failure.

The real need is for backup because it
is easy enough to corrupt a boot drive with bad installations,
viruses, etc. At worst you are only a short period of time behind if
you have to replace with the backup - assuming you backup often.
Click to expand...

So backup your OS partition to another drive, partition, or
even another system.
 
i dont' know that it will have a lot to do with which RAID1
card you chose, as you'd be looking at logically disabling
the drive access through windows, and/or physically
disconnecting power to it, IF you want it powered off too.
Neither of these aspects depend on which card you had
installed. Why would you expect the primary AND backup
drive to be corrupt simultaneously if backup wasn't
disabled? Virus? I suggest looking more at actual virus
trends if that's the case, focusing on real world observed
exploits to determine if this is a valid concern/risk.
Personally I do the RAID1 backup then have an offline
drive/system that manually backs up the online version.
Click to expand...

I install a lot of software and sometimes the installation "corrupts"
my disk. Rather than spend time trying to recover from that disaster,
I remove the disk and replace it with one that I cloned before I did
the install. That way I know I am back where I originally started. I
use Acronis TrueImage CD to perform the cloning process, which means I
have to reboot to the CD, push buttons, etc. That Enermax DynaBacker
was a RAID 1 that offered a Backup function that would have suited my
needs if it had worked as advertised. But alas, it did not and I am
looking for something that is functionally the same.
So backup your OS partition to another drive, partition, or
even another system.
Click to expand...

I do that now, but as mentioned above I am looking for something in
hardware like RAID 1 Backup. When I had the Enermax unit I would
schedule a backup at 4:00am so I started each day with a fresh
recovery disk. If Enermax had furnished me with a spare tray, I could
have kept a copy from earlier backups just in case the most recent was
corrupted from something I overlooked the day before.

That system worked perfectly for me, in principle. But it required me
to physically swap disks out of the second tray which is a bummer.
Unfortunately it looks like the actual manufacturer, a Taiwanese
company called "Etrunk" is no longer in business on the web. Attempts
at trying to contact them previously met in failure.

It would seem a simple matter of providing a RAID 1 Backup utility as
long as it flushed everything to the backup disk before disengaging.


--

Greatest Movie Line Ever
http://home.houston.rr.com/rkba/MovieLine.wmv

"What is history but the story of how politicians have
squandered the blood and treasure of the human race?"
--Thomas Sowell
 
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