# promise ide raid

## col

Can I set up a promise ide raid mirror with hot swap support....so when I remove the mirror drive & plug in a new one it will do a rebuild ?

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## mglauche

yes.

use "modprobe pdcraid" before you make partitons on gentoo,

then use /dev/ataraid/discXX/disc as the device.

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## col

does it support hot swapping of drives ? is there a howto somewhere ?

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## mksoft

No it doesn't support hot swap. I tried installing one with Debian server last week (RAID1 config). 

After the installation I pulled the plug from one of the HD's (to simulate  HD crash), the system started timing out until it was completely unusable.

When I rebooted it could not even boot, looks like a joke of a RAID if it dones't helps the system keep going when HD crashes.

I ended up bying a real IDE RAID controller (from LSI Logic), which passed all the tests with flying colors, and when the HD reconncted it started rebuilding the RAID without intervention - the way it should work  :Exclamation: 

I also recommend using hotswap drive bays for the IDE drives, make replacing harddrives on failure while the system runs easier and safer.

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## klieber

moving to hardware forum.  AFAIK, there is no way to hot-swap an IDE-based RAID.  Something about the way ATA works that won't let it happen.  (could be totally wrong, however.  :Smile: )

--kurt

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## col

hot swap is supported in windows....surprised there is no support for linux.

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## rommel

dont be surprised , its software based raid 'el chepo' stuff that needs windows drivers to work correctly...proprietary stuff like that isnt much good under linux....and its not like promise will release the info to the linux community to come up with a solution....i think unlike linux itself in thei instance you get what you paid for.

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## mksoft

 *rommel wrote:*   

> dont be surprised , its software based raid 'el chepo' stuff that needs windows drivers to work correctly...proprietary stuff like that isnt much good under linux....and its not like promise will release the info to the linux community to come up with a solution....i think unlike linux itself in thei instance you get what you paid for.

 

Correct. And if you're gonna use software raid why not go with Linux's software raid solution  :Question: 

I'm sure the kernel raid does far better job than Promise's software raid (under Linux at least).

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## col

software raid ? but it does not support hot swap.....promise support a number of linux distros (not gentoo) as do highpoint but I cant find any open source support. I assume the binary drivers support hot swap.

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## mksoft

 *col wrote:*   

> software raid ? but it does not support hot swap.....promise support a number of linux distros (not gentoo) as do highpoint but I cant find any open source support. I assume the binary drivers support hot swap.

 

From the tests I've done with promise and Debian it doesn't support hotswap as well, bit what bothered me the most was the the system stopped working when I've killed one of the HD's. So promise doesn't support hotswap as well, in that case what's the differenece between that and the Linux software raid (promise's raid is software as well).

I could get access to the raid with Gentoo's bootable cd, but their solution is not good (at least under Linux), that's why I ended up bying  LSI Logic. It is hardware raid solution (yes, with dedicated CPU on board).

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## col

But Promise dont officially support Debian ? which version of thier drivers are you using out of these ?

http://www.promise.com/support/linux2_eng.asp?mode=linux_download&product_id=15

Interesting to see that highpoint have an open source driver :

http://www.highpoint-tech.com/hpt3xx-opensource-v13.tgz

I compiled this without probs on my gentoo system ..... the redhat release supports hot swap & with a bit of mucking about I reckon you could get it running on gentoo as well as the raid admin GUI ....?

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## mksoft

 *col wrote:*   

> But Promise dont officially support Debian ? which version of thier drivers are you using out of these ?
> 
> http://www.promise.com/support/linux2_eng.asp?mode=linux_download&product_id=15
> 
> 

 

Why should it officialy support any distro at all  :Question:  All distros are using the kernel, promise should provide drivers for that kernel. Why should it support one distro  :Question:  You don't see vmware providing kernel modules only for RedHat.

Hardware soultions shouldn't dictate which distro you use. What happens when you want to switch distros  :Question:  Relying on binary only drivers for RAID is a risk IMHO. This is not like using binary drivers for graphics cards (like nvidia) which can be replaced easily. What happens when the vendor stops supporting them  :Question:  You won't upgrade your kernel/distro  :Question: 

The LSI soultion worked out of the box, with the driver supplied in the stock kernel, no need for binary/special addon modules, and is maintained in the kernel tree.

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## col

Anyway possibly thats why you couldnt get it working with Debian ?? who knows ??....Promise & Highpoint controllers are commonly built into motherboards these days which is why I would prefer to use them but from what you say the LSI controller looks like a good option .... Personally I have the promise controller on my motherboard but wish I had the highpoint now since I have found there is no open source support for my Promise chip.

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## mksoft

Yes, HighPoint looks like a better solution from promise. I had the promise controller on the server's board (Intel ClearWater) as well, now it just sits there consuming power  :Sad: 

Have you tried 3ware solutions  :Question:  I've read some good reviews about them in the past (regarding to Linux), wonder what experience others have with it.

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## rommel

why dont you just use the raid controller as two more ide channels and use LSR raid 1 it will support hotwap

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## col

I am using my promise controller which supports UDMA6 with a UDMA6 maxtor drive in non raid mode which works fine. What is LSR ??

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## rommel

LSR is linux software raid...you can set up a mirrored array using it...it would be the same as promise or highpoint in windows but its actually better ...better algorythm i guess cuz it tends to out perform in raid 0 anyway...as for mirroring well speed isnt the issue so it doesnt matter but i would think it is also more efficient at raid 1 also then its winblows counter parts.

the downside is you cannot have a windows on the array....its linux only..which is how it really should be...lol

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## col

 *rommel wrote:*   

> why dont you just use the raid controller as two more ide channels and use LSR raid 1 it will support hotwap

 

from the LSR howto re hotswap:

Hot-swapping IDE drives

Don't ! IDE doesn't handle hot swapping at all. Sure, it may work for you, if your IDE driver is compiled as a module (only possible in the 2.2 series of the kernel), and you re-load it after you've replaced the drive. But you may just as well end up with a fried IDE controller, and you'll be looking at a lot more down-time than just the time it would have taken to replace the drive on a downed system.

The main problem, except for the electrical issues that can destroy your hardware, is that the IDE bus must be re-scanned after disks are swapped. The current IDE driver can't do that. If the new disk is 100% identical to the old one (wrt. geometry etc.), it may work even without re-scanning the bus, but really, you're walking the bleeding edge here.

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