Linux sees both drives on my FastTrack100 TX2 RAID

[AluminumStudios]

I just installed a Promise FastTrack100 TX2 in a Red Hat Linux 9.0 machine. I used the card's BIOS to configured 2 drives which are mirrored.

When I run the Hardware Browser in Linux it sees BOTH hard drives as /dev/hde and /dev/hdg!!! It should see a single drive (the mirroed volume.) Why is Linux aware that there are 2 drives hanging off the IDE RAID controller? How do I mount it and how do I be sure that it is mirroring the drives properly?

HELP PLEASE!

 

[mikecel79]

The Promise FastTrak TX 2 is a hardware/software RAID controller so you'll need drivers to load for Linux. I'm nto sure if they were included in Redhat 9 or not. Probably not from what you describe. Linux probably took it's best guess as to what IDE controller it is and is using it as a normal controller instead of in a RAID array.

 

[AluminumStudios]

Can you or anyone else recommend a pure hardware IDE RAID controller (inexpensive) that would work in without drivers? One that would simply appear as a SCSI or IDE device despite what is attached to it ...

 

[VirtualLarry]

I think Adaptec sells an actual hardware IDE RAID controller, as does 3Ware.

 

[n0cmonkey]

There was an interesting thread about accusys hardware the other day on misc@openbsd. Apparently it should work just about everywhere.

 

[drag]

I beleive you should look at a combination of Linux software RAID and LVM (logical volume management)

Linux software RAID is very fast. Faster then even pure hardware RAID in most cases. (the hardware raid will have a 200mhz or so CPU dedicated to it vs the 2.0+ ghz cpu you use).

And LVM will allow you to resize partitions on the fly and modify them as your needs change.

Hell with SATA and it's ability to be hotwappable, I beleive that you can probably plug in a new IDE device, partition it, format it, add it to your software RAID array and then extend the logical volumes to use the extra space..

And have it all completely done without even having to shut down your computer.

LVM + Software RAID overview
LVM howto
Software RAID howto
Learning LVM, part 1

One of the major advantages to this way of doing things is that you can all the nice goodies, and with SATA probably get 90% of the features of hardware RAID, without having to buy any special hardware.

You can just use the regular IDE controllers + mostly generic IDE to PCI adapters without any special drivers outside those just needed to operate the IDE controllers. Although I'd probably only want to do this with all the harddrives in "master mode", because having drives as slave to a master that is on the same array can realy slow things down.

edit:

Plus you can do RAID 5 without any super expensive setups, all you need is just 3 drives and a extra controller, which you already have.

 

[drag]

I found this interesting website here..
experimental Unix raid benchmarks

This guy had recently (then) upgraded his file server's RAID array. Peopel kept telling him that Linux software RAID was faste. So then he decided to run some benchmarks on them. And he was very extensive and documented everything...

He compared various OSes running hardware vs software RAID.

Execuative summary:

Basic configuration and targetted file systems

The specification of the benchmark machine is Pentium III 933 MHz, FSB 133MHz, 640MB memory for bonnie++ or 128MB memory for iozone, TUV4X motherboard, IDE card 3ware Escalade 7506-8. Target raid systems are:

* RedHat Linux 9 software RAID5 and hardware RAID5
* NetBSD 1.6ZC (current at 2003/9/21) software RAID 5 and hardware RAID5
* FreeBSD 5.1 software RAID 5 (vinum) and hardware RAID5

Conclusion

For the case of read/write, the difference of file system didn't show dramatic differences. The total read/write speed is ruled by the RAID system. The comparison of read/write speed is something like this:

* Write:
o Linux software RAID5 25MB/s
o NetBSD software RAID5 10MB/s
o FreeBSD software RAID5 5MB/s
o Linux hardware RAID5 10MB/s
o NetBSD hardware RAID5 25MB/s
o FreeBSD hardware RAID5 20MB/s
* Read:
o Linux software RAID5 45MB/s
o NetBSD software RAID5 33MB/s
o FreeBSD software RAID5 25MB/s
o Linux hardware RAID5 25MB/s
o NetBSD hardware RAID5 30MB/s
o FreeBSD hardware RAID5 24MB/s

The only thing that came close to Linux's software RAID performance was a NetBSD Hardware RAID setup. And the RAID controller needed to do this cost 15 times as much as the generic IDE controllers that would do the same in Linux.

 

[Nothinman]

Why is Linux aware that there are 2 drives hanging off the IDE RAID controller?

Because it's a cheap software RAID controller, the real RAID is done in the driver in software. The only hardware piece is the little bit of magic to make it bootable.

RH 9 is pretty old, get something newer and it'll probably already come with the right software RAID driver for your card.

 

[Klixxer]

Originally posted by: mikecel79
The Promise FastTrak TX 2 is a hardware/software RAID controller so you'll need drivers to load for Linux. I'm nto sure if they were included in Redhat 9 or not. Probably not from what you describe. Linux probably took it's best guess as to what IDE controller it is and is using it as a normal controller instead of in a RAID array.

No it is not, it is software raid made in a flash chip with a driver required to understand the flash chip.

It is NOT hardware RAID in any way.