Raid O total

[keithallenlaw]

When you Raid 0 two HDD's, will the total capacity be the size
of one HDD, or the total of both combined?

I have a pair of 300gig Raptors in Raid 0, and it shows up as
C/: = 600gigs. The tech at the local PC store said I have
something wrong, and it should show only 300gig in RAID 0.

Me thinks he's wrong.

 

[Jeroen1000]

He's confused with raid 1 (mirroring).

 

[drescherjm]

Me thinks he's wrong.

Me thinks he does not know a thing about raid...

 

[DrFreeze]

Me thinks he does not know a thing about raid...

methinks he is just confusing raid 1 and 0, i did too, untill i read the following line somewhere:

"The 0 in Raid 0 stands for the amount of data you have left when one drive dies"

 

[Trepidati0n]

methinks he is just confusing raid 1 and 0, i did too, untill i read the following line somewhere:

"The 0 in Raid 0 stands for the amount of data you have left when one drive dies"

I find that funny yet a good mnemonic.

 

[Tolyngee]

"The 0 in Raid 0 stands for the amount of data you have left when one drive dies"

While RAID 0 has no redundancy, to say you lose all data when one drive fails is also false.

Easier to just remember the logic of 1=true, 0=false regarding redundancy.

Only one level of "RAID" doesn't have redundancy, and it's the one that already tells you it's false.

 

[Trepidati0n]

Can you explain that data loss is not absolute if a drive dies in RAID0? If the argument is a very small file might fit in a stripe is not legitimate.

 

[Biznatch]

While RAID 0 has no redundancy, to say you lose all data when one drive fails is also false.

Easier to just remember the logic of 1=true, 0=false regarding redundancy.

Only one level of "RAID" doesn't have redundancy, and it's the one that already tells you it's false.

You're right, you only lose half the data. But that missing portion of data make the rest of the data useless. So you can play word games, but if a drive in raid 0 dies, all of the data on the array is toast.

 

[Tolyngee]

Can you explain that data loss is not absolute if a drive dies in RAID0? If the argument is a very small file might fit in a stripe is not legitimate.

Wow, [H] ain't what it used to be if that honestly needs to be explained.

Do you really believe data is completely gone in a RAID 0 if just one drive is gone?

While I wasn't even considering stripe sizes, some of these stripe sizes are 1MB+. A lot of data can be 100% intact inside of 1MB. People have been given life sentences and executed over data that fit on a 360KB floppy.

Say you have 12 2TB HDs, so a 24TB RAID 0 array. Say there's evidence of a crime all over this array, like it's completely full of child porn.

But in busting the perp, the cops tell you the perp was able to destroy one, but only one of the HDs.

I sincerely hope you're not on their payroll in the forensics lab if your answer to them is "sorry, without all of the HDs, there is no way to salvage any data as evidence. It's all completely gone."

Even some computer illiterate cop would know that's bullshit.

You're right, you only lose half the data. But that missing portion of data make the rest of the data useless. So you can play word games, but if a drive in raid 0 dies, all of the data on the array is toast.

That's assuming a two-drive array. RAID 0's only limitation is a minimum of two drives. No real max.

But I'm not playing word games, your data isn't toast.

It's disappointing on here in this sub-forum to have anyone suggest otherwise.

 

[drescherjm]

Say you have 12 2TB HDs, so a 24TB RAID 0 array.

That is insanity but I imagined that more than 2 drives or an unusually large stripe size were used in your scenario.

 

[adi]

Semantics people.

RAID 0 doesn't mean absolute data loss, if you have deep pockets and don't mind shipping the drive(s) to a data recovery firm. Then again, that's the same solution if you only have a JBOD drive fail.

A better term for the people that like to think of obscure scenarios is that RAID 0 means "you cannot recover gracefully or rebuild from parity easily from a single drive failure"

 

[john4200]

Say you have 12 2TB HDs, so a 24TB RAID 0 array. Say there's evidence of a crime all over this array, like it's completely full of child porn.

But in busting the perp, the cops tell you the perp was able to destroy one, but only one of the HDs.

I sincerely hope you're not on their payroll in the forensics lab if your answer to them is "sorry, without all of the HDs, there is no way to salvage any data as evidence. It's all completely gone."

Even some computer illiterate cop would know that's bullshit.

As drescherjm wrote, that is a crazy setup. RAID 0 is not used for storing a bunch of data files -- it is mostly for fast temporary storage.

But to go with your crazy example, say the chunk size is 512KB. Then it is possible that files as large as 512KB x 11 = 5.5MB are intact. But it is not likely. Most of the files that big will have a hole in them. But there is a better than even chance that a given 2MB file is intact. But the problem is that the filesystem metadata has holes in it. So you probably have to reconstruct the files by scanning them sector-by-sector, rather than reading some allocation table.

If the files are mostly video, then a clever reconstruction program could probably salvage some of the files with holes in them. So you would have a video file with missing bits, but some of it would be viewable

So in your crazy scenario, yes, data could be salvaged.

But in a realistic scenario, it would be a long, tedious job to salvage much of the data. Most people would just consider it lost. Especially since most sane people do not store irreplaceable data in a RAID 0.

 

[Trepidati0n]

Wow, [H] ain't what it used to be if that honestly needs to be explained.

Do you really believe data is completely gone in a RAID 0 if just one drive is gone?

I know that. You are just being pedantic. Seriously.

1. The typical stripe size is not in the megabytes.
2. The typical file will be bigger than a stripe
3. Therefore, for 99.9%+ of cases...all files are lost if a drive is lost. I really don't want to look at half a picture of my mother.

 

[Monkey God]

Semantics people.

RAID 0 doesn't mean absolute data loss, if you have deep pockets and don't mind shipping the drive(s) to a data recovery firm. Then again, that's the same solution if you only have a JBOD drive fail.

A better term for the people that like to think of obscure scenarios is that RAID 0 means "you cannot recover gracefully or rebuild from parity easily from a single drive failure"

And at an absolute minimum at LEAST 50% of all data will be gone. Depending on how the file is structured, if even a small part of the file is missing, the file is useless. Compressed files, .exes, .dlls, etc.

For all intents and purposes, 99.99% of users who suffer this sort of failure are screwed.
keep the semantic BS for a political argument.

 

[ghost6303]

"The 0 in Raid 0 stands for the amount of data you have left when one drive dies"

Wow, [H] ain't what it used to be if that honestly needs to be explained.

Do you really believe data is completely gone in a RAID 0 if just one drive is gone?

no one ever said the drive gets disintegrated or all data gets dban'd or is otherwise completely gone by a disk dropping out of a RAID 0. take some midol, calm down, and reread what context all of this was written in.

 

[Krazypoloc]

You're right, you only lose half the data. But that missing portion of data make the rest of the data useless. So you can play word games, but if a drive in raid 0 dies, all of the data on the array is toast.

The data integrity is lost if 1 drive fails as there will still be data on the other drive/drives just not usable data.

 

[drescherjm]

The data integrity is lost if 1 drive fails as there will still be data on the other drive/drives just not usable data.

Some of it can be usable but there are several factors that determine how much work recovering will take and the possibility of recovery. This was discussed above so I will not repeat that again..