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By Mike B.
Notes on OS X: This article was written before OS X was released. OS X 10.1 and later have builtin support for RAID 0 (striping) and RAID 1 (Mirror). Softraid was not OS X compatible in versions up to 2.x - version 3.0 released in late August 2003 is OS X compatible, but the first 3.0 release is not bootable from the RAID volume.)
Notes on IDE RAID cards:
This page assumes you've already installed the Softraid application on your system. You simply double-click on the Softraid icon to prepare the drives. The images and text below describle the steps required to setup the RAID array. The total time required is only a few minutes (less if you accept the defaults as recommended).
Note that as mentioned on the previous drive install page - you must have a PCI IDE card controlling the IDE drives to install any Mac RAID software on them. IDE drives connected to the onboard IDE controller will not appear in the RAID software list of devices as it only scans for SCSI drives. (The PCI IDE controller is seen as a SCSI device by the MacOS, which allows drives connected to the card to appear in the list of SCSI drives.)
Initializing the Drives in Softraid
When you first run Softraid with the new drives connected, you'll need to install the Softraid driver (or initialize the drives) via Softraid's menu options. The image above shows a new/blank drive (top icon) and a drive with Softraid's driver installed (lower icon).
After selecting a disk in the right-hand column, select 'install driver' from the Softraid 'Disk' menu and the following driver paramaters box will appear.
Installing Softraid Driver (Paramaters Screen)
For these tests the default options (as shown below) were used. (Just click the 'OK' button to accept them and dismiss this dialog.) The optional Photoshop acceleration increases ram used by the driver but is said to accelerate Photoshop v3 or v4 (not currently compatible with Photoshop v5.x according to the Softraid web site setup page, customization section). The slider for 'concurrent I/Os' can be increased which also increases memory usage. In most cases the default IOs setting will be fine.
The defaults are considered the best general settings but if you want to experiment, read the Softraid Advanced Techniques page. As noted above, the latest info I have says the Photoshop acceleration option is compatible with Photoshop v3 and v4 only so I did not enable it as I'm running Photoshop 5.5 on this system.
Softraid has a mode page settings option (advanced driver/disk settings) but to avoid confusion I'm not covering it here. Most users will not have to change the defaults. One note: I could not enable write caching in the mode page settings with these IDE drives.
Drag Drives to Create RAID Volume
Once you've installed the Softraid Driver, simply select the drives you want to form the array and drag them to the left hand column which will cause the 'Create New Volume' dialog box (below) to appear:
Creating the Softraid Volume
This is where you set the type of the RAID volume in the drop-down menu (Striped RAID 0 is the fastest - see the Softraid site for info on RAID Mirror and other options), the size of the RAID volume, its name, and optionally alter the stripe unit size (the default setting is recommended for most users). Stripe unit size defaults to 128 blocks (64KB), which means that's the 'chunk size' (so to speak) of data that will be written to each drive in the array.
You can also check-off the 'HFS+' option to have the disk formatted in HFS+. This saves a lot of disk space if you'll be working with smaller files and in my tests, seems to have no negative effects on performance. (I was originally surprised at this, due to experience with the PC's FAT32 vs FAT16. HFS+ has more blocks/volume to increase storage efficiency, so I expected more overhead and reduced file IO speed but my tests of Ultra2 SCSI cards showed HFS+ was as fast or faster than HFS.)
Softraid Volume Created
After defining the RAID volume, the Softraid window will appear as shown above. For this article, two 27GB Maxtor IDE drives were set as a single RAID Volume. (Primarily due to the binary vs decimal system [1024 vs 1,000], the 27.2GB drives format to 25.42GB of usable disk space each.)
Drive Sleep Note: Since Softraid was designed for high-performance (servers, etc.) the driver will not power down in sleep mode (at least the version I used). This is also true of some other disk drivers. (Note: Also some PCI controller cards themselves do not support the "deep sleep" mode of later Macs - B&W G3, Yikes G4/PCI and older macs do not support "deep sleep", where the fans turn off, etc.)
For a list of specific Softraid hardware/software compatibility issues see this Softraid's web site.
I welcome other feedback on IDE Raid Performance - please list your Mac model, OS version, IDE PCI Card, drives used, Raid Software/version, etc.
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