IDE HDs II

Summary:

• RAID
• S.M.A.R.T.
• Performance Tuning

RAID

RAID (Redundant Arrays of Independent Disks) comes various flavors, with RAID-0 (striping) and RAID-1 (mirroring) being the most common. RAID can either be done in hardware (using a controller like the ubiquitous PROMISE RAID chips and controllers) or in software.

On-board RAID controller chips by Promise (e.g. on the Asus A7V) should get detected by the installer and work. The HPT368 (UDMA/66 RAID) should work, too, but might require some special boot loader parameters (read the 'HPT366 chipset support' paragraph in /usr/src/linux/Documentation/Configure.help).
If you want to use a controller card, you will usually have to download and install drivers from the vendor's page. The IDE controller list on linhardware.net has more information on this topic. Another valuable source of information is RAID solutions for Linux.

section index

S.M.A.R.T.

S.M.A.R.T. is the 'Self-Monitoring, Analysis and Reporting Technology' used in most modern IDE hard drives. It is used to check the reliability of the drive and predict drive failures. To put this technology to use in GNU/Linux, you need to enable S.M.A.R.T. in your system's BIOS and you need a program like the UCSC S.M.A.R.T. Suite or ide-smart (Mandrake Contrib RPM). They allow you to run tests (even periodically) and will warn you, if drive parameters drift out of range (indicating an upcoming drive failure).

Handling is very simple (as 'root'):

ide-smart -d /dev/{device} -q

will run a quiet test, only returning messages if there was an error.

section index

Performance Tuning

• The first rule is to refrain from connecting any kind of slave device to a port which already has an IDE master disk. If you really need a second disk, use the second port, and if you've already got a CD/DVD there, get a controller card.
• The second rule is to keep cables as short as possible. The longer the cable the higher the possibility of data transfer errors.
• More RAM ;-). GNU/Linux makes a generous use of RAM for caching disk accesses. Low memory resources will lead to thrashing (i.e. swapping memory to and from the hard disk). Yes, there is the swap file, but the best swap file is an unused swap file1.1
• Think big1.1 Larger disks are (usually) faster. Remember however that more speed in most cases also means more heat and more noise.

It isn't all that dangerous provided you know what you are doing and if you use the right options. And the disk speed will increase significantly even with the conservative settings I'm going to describe here.

hdparm -i /dev/hd{x}

hdparm /dev/hd{x}

hdparm -Tt /dev/hd{x}

Optimization Examples

Since I usually use

hdparm

hdparm -c3 /dev/hda

Now the benchmark shows a value around 5.8 MB which is already a significant increase.

What about (U)DMA?

hdparm -d1 /dev/hda

The benchmark takes a huge leap up to 15 MB/sec. Note that this command will automatically put the drive to the highest available transfer mode (UDMA/33 here), so there is no need to specify the

-X34

And that's all there is to it:

hdparm -c3d1 /dev/hda

-m16

-u1

You might have heard about the

hd{x}=autotune

Mandrake Linux user Roger shares his thoughts:

"One could either add to '/etc/lilo.conf':

append=" hda=dma hdb=dma hdd=ide-scsi quiet hdc=ide-floppy opti"

I'm also seeing some other options for the append line in 'lilo.conf' such as

idex=ata66

~# WDC WD400BB-00AUA1     40GB   100MB/sec   7200RPM UDMA5 hdparm -c1 -m0 -d1 -X69 -S253 /dev/hdg

~# WDC WD102BA 10.2GB    66MB/sec    7200RPM UDMA4 hdparm -c1 -m0 -d1 -X68 -S253 /dev/hdf

Now, add this to your run level.  I used /usr/bin/ksysv (as root) to add this to my run-level 5.  An easier and less messy way of doing this is just adding these few lines anywhere inside your '/etc/rc.d/rc.local', only con is that it will execute at the end of the boot process. Since I have ultra dma hdd's, I enabled udma option by adding the "-X" option.  Not well documented in the man page of hdparm, so here's the options for "-X": 33    multiword DMA mode1 66 UDMA2 68    UDMA4 (My two Ultra66 hdd's support this) 69    UDMA5 (My Ultra100 hdd supports this)

To find out of which your hdd supports & is currently set to, do the following:

# hdparm -i /dev/hdx<br> DMA modes: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5

There's another option called

multcount

Mandrake Linux user Hoyt Duff adds:

"You might want to give the boot option

ide0=0x1f0

floppy=daring

Sleep Mode

hdparm

hdparm -S{xxx}

man hdparm

Notice that the hard drive 'sleep' function puts a great deal of mechanical strain on the hard drive when 'waking it up'. Furthermore does the Linux drive access cache prevent a drive with mounted partitions on it from going into 'sleep' mode. The 'noflushd' package from your Mandrake Linux CD enables you to work around that. You should make sure to its man page before using it, though.

Once you've found a suitable setting, execute the 'hdparm' command again, adding the 'k' option. This will preserve your settings beyond the current session.

section index

Related Resources:

man smartctl

man hdparm

Revision / Modified: Dec. 18, 2001 / Feb. 13, 2002
Author: Tom Berger

Legal: This page is covered by the GNU Free Documentation License. Standard disclaimers of warranty apply. Copyright LSTB and Mandrakesoft.