Hello all -

First off, although I consider myself well-versed in Mac 
stuff, I'm a total newcomer to "RAID" and the fine points as 
to how it is configured.

I recently picked up a couple of 1tb drives and a USB 2-bay 
enclosure that is supposed to support RAID "mirroring", as 
well as "striping". You can view the enclosure here:
http://www.shop4tech.com/item8916.html
(I realize this link may soon disappear)

What I want to do is create a "mirrored" RAID. I believe 
that is two 1tb drives onto which I can do backups 
"simultaneously, side-by-side", and then have 2 
"independently-usable" drives if need be.

The enclosure is simple, in that on the back there are no 
configuration switches - just a USB port, power cord port, 
and on/off switch. On the front, it's just a matter of 
sliding in the drives and closing the door, then powering up.

Well, ok. I did that, and then opened Disk Utility to 
initialize them.

BUT - DU doesn't "present to me" TWO drives in need of 
initialization. It only presents ONE.

It shows up in the "top line" (physical drive) as:
"2 TB ST31000f 28AS Media"
Immediately below that is a single logical volume (after 
initialization).

Before I create the RAID, am I not supposed to see TWO 
drives (from which to create it)?

I'm _guessing_ that this could be something to do with the 
USB controller on the drive itself, in that it is 
automatically combining the two drives "into one". I realize 
this might be an inherent limitation with USB, or perhaps a 
fault in the design of this particular enclosure. Perhaps I 
should consider an enclosure that is more sophisticated. But 
for $25 shipped, it was worth a chance.

How do I get the enclosure (and Disk Utility) to "see" that 
I have TWO drives of equal size, and create the mirrored 
RAID from that point?

Thanks,
- John

In article <4c7d2a6d$0$17427$2c56edd9@usenetrocket.com>,
 John Albert <j.albert@snet.net> wrote:

> Hello all -
> 
> First off, although I consider myself well-versed in Mac 
> stuff, I'm a total newcomer to "RAID" and the fine points as 
> to how it is configured.
> 
> I recently picked up a couple of 1tb drives and a USB 2-bay 
> enclosure that is supposed to support RAID "mirroring", as 
> well as "striping". You can view the enclosure here:
> http://www.shop4tech.com/item8916.html
> (I realize this link may soon disappear)
> 
> What I want to do is create a "mirrored" RAID. I believe 
> that is two 1tb drives onto which I can do backups 
> "simultaneously, side-by-side", and then have 2 
> "independently-usable" drives if need be.
> 
> The enclosure is simple, in that on the back there are no 
> configuration switches - just a USB port, power cord port, 
> and on/off switch. On the front, it's just a matter of 
> sliding in the drives and closing the door, then powering up.
> 
> Well, ok. I did that, and then opened Disk Utility to 
> initialize them.
> 
> BUT - DU doesn't "present to me" TWO drives in need of 
> initialization. It only presents ONE.
> 
> It shows up in the "top line" (physical drive) as:
> "2 TB ST31000f 28AS Media"
> Immediately below that is a single logical volume (after 
> initialization).
> 
> Before I create the RAID, am I not supposed to see TWO 
> drives (from which to create it)?

If the enclosure advertises it as being RAID capabale, that means you 
have *hardware* RAID in the enclosure, and the result is what is shown 
to your Mac. I.e. your mac can not access the drives independently for 
creating a *software* RAID. There are pros and cons for both hardware 
and software raid so let's not go into that.

But it seems the enclosure is now configured for striping (RAID0) when 
you wanted it to be st up for mirroring (RAID1). Striping makes for 
faster file access while doubling the risks for data loss. Mirroring 
with hardware raid is generally the same speed as reading/writing to a 
normal disk (and since you're using USB, speed doesn't seem to be a 
concern to you either way).

I would dig up the manual for the enclosure and find out how you make 
it configure the disks in RAID1.


After having written all that, I actually visited the link you pasted 
and this unit seems to be a device like the Drobo - you can actually 
put any size disk in it (up to 2x1TB it seems) and it will always 
configure it in RAID0 (it states explicitly that it's 
non-configurable). So, chances are that it has an internal file system 
on the disks (like the Drobo) and shows them as a HFS disk to your 
computer, but it's all done internally, which of course impacts speeds 
in read/write (the Drobo is notorious for being slow)

I should have looked at the link first :)



-- 
Sandman[.net]

In article <4c7d2a6d$0$17427$2c56edd9@usenetrocket.com>,
 John Albert <j.albert@snet.net> wrote:

> Hello all -
> 
> First off, although I consider myself well-versed in Mac 
> stuff, I'm a total newcomer to "RAID" and the fine points as 
> to how it is configured.
> 
> I recently picked up a couple of 1tb drives and a USB 2-bay 
> enclosure that is supposed to support RAID "mirroring", as 
> well as "striping". You can view the enclosure here:
> http://www.shop4tech.com/item8916.html
> (I realize this link may soon disappear)
> 
> What I want to do is create a "mirrored" RAID. I believe 
> that is two 1tb drives onto which I can do backups 
> "simultaneously, side-by-side", and then have 2 
> "independently-usable" drives if need be.
> 
> The enclosure is simple, in that on the back there are no 
> configuration switches - just a USB port, power cord port, 
> and on/off switch. On the front, it's just a matter of 
> sliding in the drives and closing the door, then powering up.
> 
> Well, ok. I did that, and then opened Disk Utility to 
> initialize them.
> 
> BUT - DU doesn't "present to me" TWO drives in need of 
> initialization. It only presents ONE.
> 
> It shows up in the "top line" (physical drive) as:
> "2 TB ST31000f 28AS Media"
> Immediately below that is a single logical volume (after 
> initialization).
> 
> Before I create the RAID, am I not supposed to see TWO 
> drives (from which to create it)?
> 
> I'm _guessing_ that this could be something to do with the 
> USB controller on the drive itself, in that it is 
> automatically combining the two drives "into one". I realize 
> this might be an inherent limitation with USB, or perhaps a 
> fault in the design of this particular enclosure. Perhaps I 
> should consider an enclosure that is more sophisticated. But 
> for $25 shipped, it was worth a chance.
> 
> How do I get the enclosure (and Disk Utility) to "see" that 
> I have TWO drives of equal size, and create the mirrored 
> RAID from that point?
> 
> Thanks,
> - John

Mirroring requires an administration tool so that you can tell it to 
rebuild from one of the drives when they are out of sync.  That same 
tool is probably what you're missing to set the RAID mode.
-- 
I won't see Google Groups replies because I must filter them as spam

Salut John

In article <4c7d2a6d$0$17427$2c56edd9@usenetrocket.com>,
 John Albert <j.albert@snet.net> wrote:

> First off, although I consider myself well-versed in Mac 
> stuff, I'm a total newcomer to "RAID" and the fine points as 
> to how it is configured.
> 
> I recently picked up a couple of 1tb drives and a USB 2-bay 
> enclosure that is supposed to support RAID "mirroring", as 
> well as "striping". You can view the enclosure here:
> http://www.shop4tech.com/item8916.html
> (I realize this link may soon disappear)
> 
> What I want to do is create a "mirrored" RAID. 


did you actually read the text in the link you provided?

i.e.: Non-Configurable, JBOD: RAID 0 - Disk Spanning function

Nothing more to be said about that enclosure...

cheers
Andreas

-- 
MacAndreas Rutishauser, <http://www.MacAndreas.ch> 
EDV-Dienstleistungen, Hard- und Software, Internet und Netzwerk
Beratung, Unterstuetzung und Schulung
<mailto:andreas@MacAndreas.ch>, Fon: 044 / 721 36 47

In article <mr-8E17B8.18272831082010@News.Individual.NET>,
 Sandman <mr@sandman.net> wrote:

> After having written all that, I actually visited the link you pasted 
> and this unit seems to be a device like the Drobo - you can actually 
> put any size disk in it (up to 2x1TB it seems) and it will always 
> configure it in RAID0 (it states explicitly that it's 
> non-configurable).

Note to John: 

While the thing you bought may share one very small quality with the 
Drobo (you can put any sized drive in it), that's about it! The Drobo is 
a much, much better solution in almost every way! 

The term "You get what you pay for" certainly applies here!

-- 
Send responses to the relevant news group rather than email to me.
E-mail sent to this address may be devoured by my very hungry SPAM
filter. Due to Google's refusal to prevent spammers from posting
messages through their servers, I often ignore posts from Google
Groups. Use a real news client if you want me to see your posts.

JR

Jolly Roger <jollyroger@pobox.com> writes:
>  Sandman <mr@sandman.net> wrote:

>> and this unit seems to be a device like the Drobo - you can actually 
>> put any size disk in it (up to 2x1TB it seems) and it will always 
>> configure it in RAID0 (it states explicitly that it's 
>> non-configurable).

> While the thing you bought may share one very small quality with the 
> Drobo (you can put any sized drive in it), that's about it! The Drobo is 
> a much, much better solution in almost every way! 

It's not even clear whether it's actually RAID 0 (striped) or
JBOD spanning.  It says both, but it's probably not RAID0 at
all and they are just calling it that.  Real RAID0 requires
the drives to be the same size for striping, as I understand it.

Either way, spanning your data across two disks without
reduncancy makes for data very vulnerable to disk failure.

DroboRAID is a variation of RAID5 - which stripes across disks
but with redundancy so that if one of the drives fails, the
drive may be swapped out and the data reconstructed from the
others.

NetGear does basically the same thing on their ReadyNAS using
their Raid5 variation they call "x-raid".

This ultra-cheap drive is very unlikely to be doing any of
these things.

> The term "You get what you pay for" certainly applies here!

So often the case!

-- 
Plain Bread alone for e-mail, thanks.  The rest gets trashed.

On 2010-08-31 12:12:13 -0700, BreadWithSpam@fractious.net said:

> Jolly Roger <jollyroger@pobox.com> writes:
>> Sandman <mr@sandman.net> wrote:
> 
>>> and this unit seems to be a device like the Drobo - you can actually
>>> put any size disk in it (up to 2x1TB it seems) and it will always
>>> configure it in RAID0 (it states explicitly that it's
>>> non-configurable).
> 
>> While the thing you bought may share one very small quality with the
>> Drobo (you can put any sized drive in it), that's about it! The Drobo is
>> a much, much better solution in almost every way!
> 
> It's not even clear whether it's actually RAID 0 (striped) or
> JBOD spanning.  It says both, but it's probably not RAID0 at
> all and they are just calling it that.  Real RAID0 requires
> the drives to be the same size for striping, as I understand it.

Generally, yes. Unless the controllers are doing something special. 
This case is simply a Concatenation of drives. Any one drive failure 
still busts the volume.

> 
> Either way, spanning your data across two disks without
> reduncancy makes for data very vulnerable to disk failure.
> 
> DroboRAID is a variation of RAID5 - which stripes across disks
> but with redundancy so that if one of the drives fails, the
> drive may be swapped out and the data reconstructed from the
> others.
> 
> NetGear does basically the same thing on their ReadyNAS using
> their Raid5 variation they call "x-raid".
> 
> This ultra-cheap drive is very unlikely to be doing any of
> these things.
> 
>> The term "You get what you pay for" certainly applies here!
> 
> So often the case!


-- 

thepixelfreak

RE:
"This case is simply a Concatenation of drives. Any one 
drive failure still busts the volume."

Not with this one. Something funny is going on.

I took the drives OUT of the dual enclosure, and initialized 
them one-by-one in my USB/SATA "docking station". After 
doing so, I had two distinct 1tb drives.

I then put the drives _back into_ the dual enclosure. Again 
shows as a 2tb SINGLE volume.

I _thought_ I had some kind of mirror set up (again, I 
freely admit I'm not sure of what's going on, or even of 
what I'm doing). So, I partitioned [what I thought was] the 
"mirrored RAID" and copied some data onto it. (Note: I'm 
creating several partitions to back up several Macs.)

Well, I became suspicious that there wasn't any "mirroring" 
at all. So I took the drives back out of the dual enclosure, 
and put them individually into my USB/SATA dock.

One of the drives had all the partitions on it, and the 
copied data. The other had nothing on it (initialized, but 
blank).

But, they both mounted in the dock as working drives (i.e, 
partitioning them in the dual enclosure did not "wipe" the 
initialization I had done to them as "single drives" - they 
kept their "individual identities".

Can't tell what's going on.

The dual enclosure does come with RAID software, but it's 
all Windows. Nothing for the "Mac side".

Other than Disk Utility, is there any other free/shareware 
software/utilities that I should consider investigating?

Thanks,
- John

In article <4c7dc889$0$17474$2c56edd9@usenetrocket.com>,
 John Albert <j.albert@snet.net> wrote:

> RE:
> "This case is simply a Concatenation of drives. Any one 
> drive failure still busts the volume."
> 
> Not with this one. Something funny is going on.
> 
> I took the drives OUT of the dual enclosure, and initialized 
> them one-by-one in my USB/SATA "docking station". After 
> doing so, I had two distinct 1tb drives.
> 
> I then put the drives _back into_ the dual enclosure. Again 
> shows as a 2tb SINGLE volume.

A concatenated RAID 0 array adds both drives to together to create a 
single contiguous volume that spans both drives. This is expected 
behavior.

> I _thought_ I had some kind of mirror set up (again, I 
> freely admit I'm not sure of what's going on, or even of 
> what I'm doing). So, I partitioned [what I thought was] the 
> "mirrored RAID" and copied some data onto it. (Note: I'm 
> creating several partitions to back up several Macs.)

The device presents the hard drives as a single drive to the system. You 
can create as many logical volumes as you want. But you can't access 
each drive individually. Therefore you cannot mirror these drives with 
this enclosure. The data on these drives is at risk as a result. If 
either one of the drives fails, you run the risk of losing some or all 
of the data on the drives.

> Well, I became suspicious that there wasn't any "mirroring" 
> at all. So I took the drives back out of the dual enclosure, 
> and put them individually into my USB/SATA dock.

It's probably a bad idea to remove RAID disks from the RAID enclosure 
and mount the separately. If you modify the data on the drives while 
mounted separately, you run the risk of corrupting the RAID array or 
losing data stored on the disks.

There is no mirroring with this enclosure.

> One of the drives had all the partitions on it, and the 
> copied data. The other had nothing on it (initialized, but 
> blank).

That's because they are a concatenated RAID 0 array. If you picture the 
two drives stacked on top of one another, data is stored on the top 
drive, and only once the top drive is full does the next drive get used.
 
> But, they both mounted in the dock as working drives (i.e, 
> partitioning them in the dual enclosure did not "wipe" the 
> initialization I had done to them as "single drives" - they 
> kept their "individual identities".

Like I said, doing this is probably a bad idea, if you intend to use 
them in the RAID enclosure.

> Can't tell what's going on.

Hopefully you know now that they are a simple concatenated RAID array.

> The dual enclosure does come with RAID software, but it's 
> all Windows. Nothing for the "Mac side".

That Windows software is probably just simple disk formatting software, 
rather than something specific to RAIDs.

> Other than Disk Utility, is there any other free/shareware 
> software/utilities that I should consider investigating?

Nope. The thing is operating as expected.

-- 
Send responses to the relevant news group rather than email to me.
E-mail sent to this address may be devoured by my very hungry SPAM
filter. Due to Google's refusal to prevent spammers from posting
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Groups. Use a real news client if you want me to see your posts.

JR

In article <jollyroger-CDF84D.00553701092010@news.individual.net>,
 Jolly Roger <jollyroger@pobox.com> wrote:
.... 
> That Windows software is probably just simple disk formatting software, 
> rather than something specific to RAIDs.
> 
I know that NetGear makes RAID boxes with Windows support in firmware on 
the box. Macs are simply not supported.

JollyRoger wrote:
"The device presents the hard drives as a single drive to 
the system. You can create as many logical volumes as you 
want. But you can't access each drive individually. 
Therefore you cannot mirror these drives with this 
enclosure. The data on these drives is at risk as a result. 
If either one of the drives fails, you run the risk of 
losing some or all of the data on the drives."
"Hopefully you know now that they are a simple concatenated 
RAID array."

OK, thanks, I see that now. Should have read more carefully 
before I bought it, but again, it wasn't much $$$.

I've come to the conclusion that RAID 1 (mirroring) isn't 
what I'm looking for.

I put the dual-bay enclosure in the attic, and mounted one 
of the 1tb drives in my USB/SATA "dock", and initialized it. 
I then repeated the process with the other drive. I now had 
two 1tb individual drives.

Next, I used my Rosewill "IDE/SATA dongle" (which I have in 
addition to the docking station) and got both drives to 
mount independently on the desktop.

I opened Disk Utility and was able to create a RAID 1 
mirrored array succesfully, with one "combined" disk icon on 
the desktop.

I found, however, that AFTER creating the RAID, DU offers no 
option to further partition the RAID volume, which is what I 
want to do (I need about 8 different partitions, each will 
have its own dedicated purpose on each drive). Strike one 
against RAID 1.

For experimentation, I dismounted the RAID 1 icon and 
powered down both drives. I then disconnected one, and tried 
re-mounting the other. Wouldn't mount up. Again, I was 
looking for a solution where I could write to BOTH drives at 
once, but be able to "break the RAID apart" and mount them 
independently if needed. I'm guessing others will say 
"impossible" and I accept that -- again, not sure of the 
limitations that a RAID 1 would impose upon me. Strike two 
against RAID 1.

So I guess I'll just have to backup/archive to the drives 
one-at-a-time, so to speak.

Just to clarify, here is what I _thought_ I could do:
1. Have 2 individual drives, each with numerous partitions 
for data
2. Create a system where I could mount BOTH drives "as one" 
and do backups to the individual partitions on BOTH drives 
simultaneously, and then....
3. "Split apart" the drives and have each as an 
independently-mountable/bootable standalone drive.
The goal was to cut in half the "copy time".
Of course, _thinking_ that you can do it has nothing to do 
with whether it's actually possible!

Is there any other method (i.e., "non-RAID") by which to do 
this?

- John