Linux Raid cards?

[David Ranch]

Since performance isn't your primary issue, do RAID5. You'll get more usable
storage that way.

Software RAID is quite good on Linux and I've used it for years. The only
problem I have with it is how Linux treats IDE and SCSI differently. For
example, the 3rd drive on a IDE chain is always /dev/hdc. But in SCSI, if you
have drives A, B, and C on SCSI IDs 0,3,4.. that's /dev/sda, sdb, sdc. Ok, now
drive B dies. Does /dev/sdb just go away? No! the C drive becomes /dev/sdb
after reboot (slides down). That's pretty evil stuff.

For HW solutions, I highly recommend 3ware cards. They make 2,4, and 8 channel
PCI controllers for both PATA and SATA. Kinda expensive but very good quality,
Linux drivers have been in the kernels for YEARS, etc.

DON'T get a Promise or Highpoint RAID card. Repeat.. DON'T. Those are
hardware "accelerated" cards (read "winmodem") and require the main CPU to do
most of the work. If a drive fails, the array usually will go offline. ONly
after a reboot, the backup drive would come online and the array would again be
available. Once the defective disk is replaced, you usually have to reboot
AGAIN and reconstruct the data to the new drive cia the raid controller's
BIOS. All this time, your server is down.

I learned this the hard way.

--David



>My current 250gb raid mirror for all my MP3s is running on my windows
>box. I'd like to move it over to linux if I can and build a dedicated
>server for my squeezebox and home audio.
>
>Anyone have a recomendation for an IDE raid card that will work good
>with linux 2.4 kernel? It must do mirroring. My current card will only
>do striping but no mirroring in the 2.4 kernel (debian stable). Hence
>the reason it's in a windows box. I'd like to keep it under a hundred
>bucks if I can.
>
>Thanks,
>
>-Healy
>
>
>
>

[Healy]

On Wed, 2004-05-05 at 22:50, David Ranch wrote:
> Since performance isn't your primary issue, do RAID5. You'll get more usable
> storage that way.

I only have 2x250gb IDE drives so RAID5 is not an option w/out shelling
out more cash.

> Software RAID is quite good on Linux and I've used it for years. The only
> problem I have with it is how Linux treats IDE and SCSI differently. For
> example, the 3rd drive on a IDE chain is always /dev/hdc. But in SCSI, if you
> have drives A, B, and C on SCSI IDs 0,3,4.. that's /dev/sda, sdb, sdc. Ok, now
> drive B dies. Does /dev/sdb just go away? No! the C drive becomes /dev/sdb
> after reboot (slides down). That's pretty evil stuff.

I fat-fingered some raid repair commands a long time ago and hosed data
when doing software raid. I've avoided using it since, nothing but my
own stupidity at the time but I've never gone back to software. Perhaps
it's time to rethink that logic :)

> For HW solutions, I highly recommend 3ware cards. They make 2,4, and 8 channel
> PCI controllers for both PATA and SATA. Kinda expensive but very good quality,
> Linux drivers have been in the kernels for YEARS, etc.

That seems to be the general feeling. They are a bit steep in price but
it sounds like they are worth it. My normal online vendor of choice
(newegg.com) does not appear to have the 2-channel card ( 7006-2 ) in
stock but they do have the bigger models. I'll do some searching around
& weigh prices.

> DON'T get a Promise or Highpoint RAID card. Repeat.. DON'T. Those are
> hardware "accelerated" cards (read "winmodem") and require the main CPU to do
> most of the work. If a drive fails, the array usually will go offline. ONly
> after a reboot, the backup drive would come online and the array would again be
> available. Once the defective disk is replaced, you usually have to reboot
> AGAIN and reconstruct the data to the new drive cia the raid controller's
> BIOS. All this time, your server is down.
>
> I learned this the hard way.

Too late!

I got a HighPoint Rocket Raid 100 about 6 months back and discovered
that raid1 is spotty in the kernel, so everything got put on a windows
xp box. I'm in the process of moving it to a debian server, hence the
reason for this message.

Thanks to everyone for the tips in the slightly off-topic thread.

-Healy