Topic: Adaptec Raid Controllers for e-smith

[Tom Keiser]

I know that e-smith offers software raid in the form of disk mirroring, but that's slow compared to real hardware raid, especially raid 5 with a cpu on the controller board and some memory for caching the array data. Adaptec has finally posted RH 7 drivers for its low-to-mid-range raid controllers on their site, and one type of driver will allow Red Hat 7 to be installed right to the raid array, instead of installing it to a separate boot drive, then adding the raid array via an RPM for separate data storage. They have a new ATA-100 controller for IDE drives (model 2400A) and another for more expensive SCSI drives (model 2100S and higher). You can see the drivers on http://linux.adaptec.com, and yes, they are GPL'd. Compared to the list of other hardware raid controllers in the e-smith documentation, the Adaptec controllers (around $350 to $450, give or take) are super-cheap, and excellent  performers.(No, I don't work for Adaptec )

The problem is that you will want both the INSTALLATION and the DATA protected by the raid drives. In a normal RH7 install, you simply type "expert" at the first LILO prompt, and a script runs which will later ask you to insert your driver diskette so that the drivers become an integral part of the installation, and re-loading them will be done automatically at boot time.

The e-smith people suggested I post here to see whether anyone would like to look into the possibility of integrating RH's "expert mode" install script variations into the e-smith install script. I am not a programmer, or I would work on it myself. I think this is a great opportunity to give e-smith, and its customers a substantial benefit in disk storage sanity and speed.

For those who are new to raid, the notion is to have 3 or more drives, where all  drives in the group contain enough information to rebuild the data on any single drive that fails (this is raid 5). This is faster than mirroring, and not as wasteful of storage space as mirroring -- if you use 3 drives, you have the combined storage of two of them; if you use 4 drives, you get the storage space of three, etc. These controllers will do other forms of raid, but this is the one people will want to have. If a drive fails, insert a new one, and the controller will automatically rebuild its data.

I hope someone finds this interesting. Who knows, there may be other drivers that can be loaded via the Red Hat "expert mode" as well.

Thank you,

Tom Keiser

[peter]

Tom, your post inspired me to try a hardware RAID-1 install using some old hardware I had lying around. DPT Smart Cache IV controller with RAID/Cache module (16 meg cache) and two IBM DFHSS2W  2g disks. It went like this:
1.Install the card and disks into a spare PC (Acer celeron 300, 80 meg RAM)
2. Boot from a DOS diskette,
3. Run the "install" program from the first of the DPT diskettes (V1.p) to set up the DPT Storage Manager.
4. Set up the drives as a mirrored pair and format.
5. Boot from the E-Smith CD (4.1.1) and install taking the "single drive or hardware RAID" option.
6. E-Smith found the DPT card straight off and installed using the EATA driver.
There is no separate boot drive, as far as E_Smith is concerened, there is a single 2 gig drive.
7. Once setup was completed, shut dwn and disconnected one of the disk power cables.
8. Rebooted, E-Smith came up normally and the only indicationof a problem was the alarm buzzer on the card was shrieking its head off!
9. Shut down and reconnected the power connector to the disk. Rebooted and noted that the DPT BIOS only found one disk. Booted to DOS (diskette) then rerun the DPT Storage  Manager.
10 Went into "Array Group Information" and it said that the array group was "degraded - one drive failed"
11. Selected the Rebuild button to repair - the rebuild took about 20 minutes.
12. Rebooted to E-Smith.

It doesn't get much simpler than that, no additional stuff needed from Red Hat.
I would expect RAID 5 to be exactly the same in terms of installing and rebuilding.
The only thing I would like to see is an indication that a drive had failed, at present it depends on someone hearing the buzzer.  The Storage Manager for Windows was able to send messages to e-mail, pagers, system message queues, etc.

The DPT cards are oldies but goodies, and the rotating LEDS on the side look cool. Like having the Night Rider car inside the case!

[Tom Keiser]

Peter:

   That "old card" you had lying around is one of the finest raid controllers made. Too bad it's no longer available -- I have one of those in my own main server with 64MB of ram, running 4 x 9GB Quantum Atlas drives on raid 5, and it's marvelous. When we set mine up, we had to use an IDE boot drive, install RH 6.0, then load their "i2o" module into the kernel at bootup to use the DPT array.

   So, either RH and e-smith have now included a driver for that DPT controller, or else you are running raid 1 (mirroring) straight from the internal bios of the DPT card. (I don't know what the "EATA" driver might be). If you are only running from the bios, your performance is less than it would be if the real DPT driver were installed. On the other hand, it works.

   As to an "indication that a drive had failed" the "storage manager" software is what you need, but I don't believe they ever wrote one for that board for Linux. The adaptec storage manager for the 2100S, on the linux.adaptec.com site might work, as it is a descendant of that DPT controller you have, but I kind of doubt it, and trying to use it may mess up your present install.

   In any event, thanks for responding, and for agreeing that installing directly to the raid drive(s) is the best way to go. Now, I just need a way to do that...

Regards,

Tom

[peter]

I had a look at the I2O driver and stuff, but they say its for the V & VI  series of controllers. Mine is the IV, it says the IV and earlier cards used a different driver and the I2O will not work.
Did a google search on EATA.DMA and came up with 1000's of hits, have a look at http:new.linuxnow.com/docs/content/DPT-Hardware-RAID/

When I frst got this card I contacted DPT about a driver, they said a driver has been built into Linux since 1.1.13 (the eata driver) and my first outing with Linux - RH6.0 -  used this and a Raid Tower I built using 7 x 1 g HP drives. So much heat and noise for 6 gigs!

Incidentally I was given the card and cache module by a Sysadmin who thought it was faulty and killing disks in his NT server. The fact that his drives were stacked one above the other with no cooling....

[Tom Keiser]

Peter:

   Oops, my card is a DPT V, and it does use the i2o driver, but has no management s/w. I guess I looked at the prices of the IV so long before buying, that's what I thought I purchased.

   Still, you have a great card, and its a pity they're no longer available.

   Thanks for the replies -- now all we need is for someone to look at the original challenge and say: "no problem".

Regards,

Tom