Sean and Peter -

If I was reading the correct specs, they said Linux up to RH 9. It is compatible with Centos/RHEL?

I may go with the 2-port version and just RAID two-80 GB drives and keep my 2-30 GB drives as extra storage.

*** Can I pre install Centos on one of my 80 GB drives and after the controller arrives, plug the 2-80 GB drives into it and then mirror the drive?

Todd

Sean O'Connell wrote:

On Fri, 2005-09-09 at 13:08 -0700, Todd Cary wrote:

...

I have not used RAID controller boards to date since I have relied on the built in RAID on the motherboards. Thanks to the informative message Byron, I realize the deficiencies of doing RAID 1 this way, especially now that the builtin is out of date with Kernel used by Centos.

I have 4 ATA drives that were configured in two pairs. I assume that I need a 3Wave controller that has 4 ports like the 7506-4LP...correct?

Do I need to install any software during the installation of Centos?

Todd-

The installation will recognize the 3ware card and the arrays that you build on it (you do this in the card bios Alt+3 at boot). As Peter said, you'll want to make sure the card is using the latest firmware (you'll need a dos boot disk and a floppy with the firmware utility on it, comes as a zip file from the 3Ware site) -- iirc, the latest version is 7.7.1 for 7xxx and 8xxx cards. You also probably want to get run the 3dmd utility as it will notify you about failed disks and other issues by email and can do background media checks... very nice.

Sean

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On Friday 09 September 2005 16:45, Todd Cary wrote:

Sean and Peter -

If I was reading the correct specs, they said Linux up to RH 9. It is compatible with Centos/RHEL?

I may go with the 2-port version and just RAID two-80 GB drives and keep my 2-30 GB drives as extra storage.

*** Can I pre install Centos on one of my 80 GB drives and after the controller arrives, plug the 2-80 GB drives into it and then mirror the drive?

Todd

Todd,

yes, they will work with the stock drivers - but for best performance and reliability you need to upgrade the firmware once the OS is installed.

When initializing a raid 1, the controller wipes out all data according to the manuals. Every now and then you hear from people that say that the controller copies everything from disk1 to disk2 and if your IDE controller sector mapping matches what the 3ware controller does, you can keep your data in tact. Unfortunately noone can tell me what controllers would work and what I am doing wrong. I've tried that twice and it didn't work for me though, so from my point of view, what you want to do, isn't going to work...

Peter.

On Fri, 9 Sep 2005, Bryan J. Smith wrote:

Peter Arremann loony@loonybin.org wrote:

...

When initializing a raid 1, the controller wipes out all data according to the manuals. Every now and then you hear from people that say that the controller copies everything from disk1 to disk2 and if your IDE controller sector mapping matches what the 3ware controller does, you can keep your data in tact.

Actually, for RAID-1, 3Ware does _not_ using additional blocking/organization, and does a direct mirror. I.e., the disks _can_ be used "normally."

For RAID-0, 10 and 5, 3Ware uses 32KiB blocking and the volumes are completely _unusable_ by anything else AFAIK (maybe LVM2-MD?).

That's not entirely correct. The 3Ware disks almost use standard raid format, it's just the raid block on each disk that is written at the end of the disk I believe instead of at the beginning. About a year a go we rescued all data from a series of PATA disks from a friend of mine when his 3Ware went bust. We were able to start the array in software raid with the right parameters. Google was my friend then

Remco Barendse redhat@barendse.to wrote:

That's not entirely correct. The 3Ware disks almost use standard raid format,

There is no "standard RAID format."

Different vendors -- be it hardware or FRAID -- as well OS software organizations use different offsets, blocking, etc... for RAID-0, 10, 3, 4, 5, etc... But the overwhelming majority of RAID implementations have a "meta-data block" or set of blocks that describe this organization. It's done so drivers, firmware or even other cards from the same vendor/code can read the disk organization.

The Device Mapper (DM) work is able to read some of these meta-data blocks to understand RAID-0, 10 and even "1e" (2 disc RAID-10, long story).

About the _only_ "industry standard" is RAID-1. I haven't seen a vendor yet who didn't do straight mirroring -- 1 sector to 1 sector.

it's just the raid block on each disk that is written at the end of the disk I believe instead of at the beginning.

Again, you are talking about the meta-data block(s). That's different. 3Ware adds those, yes. It's mainly for managing the disk. Most vendors do put them at the end, yes. But vendors differ on their meta-data blocks. But most have been reverse engineered and documented.

I'm talking about being able to take a standalone disk and put it into a RAID-1 array on a 3Ware card. You can because RAID-1, unlike RAID-0, 10 or 5 on a 3Ware card, does _not_ stripe data in 32KiB (default) blocks.

About a year a go we rescued all data from a series of PATA disks from a friend of mine when his 3Ware went bust. We were able to start the array in software raid with the right parameters. Google was my friend then

Was it RAID-1? Or RAID-10 or 5?

RAID-1 volumes are _extremely_easy_ to read.

RAID-0, 10 or (not yet?) 5 requires Device Mapper (DM) or another software implementation _must_ read the 3Ware meta-data blocks so it can understand the striping/blocking organization. Not being able to read the meta-data blocks will prevent you from finding the _exact_ striping positions and blocking size (32KiB is the default) for RAID-0, 10 and 5.

But RAID-1 is just straight mirroring. It's not as important if you can't read the meta-data block.