SoftRAID 2.x Setup Information
Setting up SoftRAID from Scratch
This section assumes you have a fresh system and DO NOT need any existing data on the drives you wish to use SoftRAID on.
First plan your volumes. The SoftRAID Quickstart, has a "Planning Chart" for driver partitions and volumes on the last page. SoftRAID allows any combination of volume types. If you are sure which volume you need go to the Mirrors, Stripes and Standard Volumes section below.
Setting up SoftRAID with All NEW Volumes
NOTE: You DO NOT need any special boot software, boot volumes, or other considerations when setting up SoftRAID unless you have a new Power Macintosh G4 or Blue-White G3 computer. See the section for those systems which discusses volume limitations.
- Install the SoftRAID driver on all your system's SCSI drives. They do not need to be initialized or formatted. A "Quick Initialize" will ensure a clean partition map.
- Delete all volumes, or simply "Quick Initialize" each disk.
- If you prepared a chart, consult it to decide which volume type to create first. Drag the appropriate disk(s) to the volumes column (shift click to select multiple drives)
- Select volume type (Stripe/Mirror/Standard), and capacity. Click OK.
- Repeat until finished.
Volumes can be deleted or added as desired at a later date without reformatting any drives.
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Setting up SoftRAID with Existing Volumes
This is similar to the above section with a few minor differences:
- Install the SoftRAID driver on each disk. Installing the SoftRAID driver will not delete existing volumes as be controlled by SoftRAID.
- Delete volumes to make room for new volumes, if necessary.
NOTE: FREE SPACE - space on a disk which has NOT BEEN ALLOCATED TO ANY VOLUMES. You must delete volumes to create free space for more volumes, rather than just deleting files inside a volume.
Setting up a New Blue-White G3 or G4 System
The Blue and White G3 and G4 Computers have some restrictions to the type of volumes you can use as bootable volumes. The boot drive on a new G4 or G3 MUST be a standard (HFS or HFS+) volume or a mirrored volume. You cannot boot a from a striped volume on one of these systems.
NOTE: Even if you have an internal IDE drive, we recommend the following to give yourself maximum flexibility should it fail:
- Create a small HFS volume for booting. This volume may be as small as 200 MB or as large as necessary. 500 MB is a good number. We recommend the same on the next disk.
- After creating bootable volumes, create Striped/Mirror/Standard volumes as necessary. If you are Mirroring your system volume, you may create one large volume to do this, or create multiple mirror volumes. We recommend separate bootable volumes for maximum data safety. (Most volume corruption problems only affect the system volume, so keeping data on a separate volume increases data safety.)
- Create an alternate method of booting your system. Some options are a Zip disk, Bootable CD, jaz cart, spare drive, or spare volume on an installed drive, or an external drive which you can easily connect to your system.
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Tips for Planning Your SoftRAID Configuration
General tips:
Keep lots of RAM, and leave Mac OS Disk Cache settings at the default, or even increase them slightly. Keep SoftRAID Read and Write acceleration settings on at all times.
SoftRAID Stripe Unit Size settings:
These are already optimized. Only if you are exclusively using your system for Digital Video will altering the Stripe Unit Size make any significant positive difference. If you have a DV system, and your drives have large RAM caches, try increasing SU to 192. Do extensive testing before and afterwards.
Mode pages:
This setting is for those with digital video expertise. Changing the settings incorrectly in this dialog box in SoftRAID can dramatically decrease performance.
EXCEPTION: Most Seagate drives purchased from a "PC reseller" have been "optimized" for Windows NT, and will perform less than optimally under Mac OS. If the Mode page settings show 16 cache segments, reset the number of cache pages to a lower number such as 3.
SCSI Tips:
2 SCSI cards or 1 dual channel card?
For small numbers of drives, placing the two drives on separate channels will not increase performance. Often performance will be slower with smaller I/O transfers. The reason is that a two channel card has additional latency from the SCSI bridge chip which allows both SCSI channels to work together. This added overhead translates into latency, which can slow small I/O transfer times on striped volumes.
U2W (LVD) SCSI and U160 SCSI
U2W SCSI (also known as LVD or Low Voltage Differential) performs best with 120 Ohm twisted pair cable. Standard 90 Ohm Ultra Wide SCSI cabling will work if you do not use long lengths. UW cabling is acceptable up to a length of approximately 1.5 to 2 meters, before the special twisted pair 120 Ohm cabling becomes a requirement.
U160 is a higher performing version of SCSI and has double the byte transfer rate of LVD SCSI. Quality cabling is essential, including all cabling INSIDE external drive enclosures. U160 SCSI requires twisted pair cabling. Some brands of "U160" drive enclosures are manufactured with standard old style SCSI cabling, which is not twisted pair. Insist on twisted pair SCSI cabling to avoid bus errors, SCSI hangs, and other problems with your system.
NOTE: An LVD or U160 SCSI chain will perform at the SCSI specification of the slowest device. If you use a slower device, such as a Ultra Wide drive on your U2W SCSI bus, all devices will run at the slower UW speeds. A slower UW operational bus will also fall to shorter UW cable requirements.
Mixing drive types, using incorrect cabling/termination, may restrict your entire SCSI bus to standard Ultra SCSI performance. Adaptec has a special "SpeedFlex technology to avoid this by allowing the SCSI bus internally and externally to be electrically isolated so as to enable both ends of the bus to operate at different SCSI speeds without the cabling problems.
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Tips For Different Types of Applications
WorkGroup Server - mission critical
You goal is Data Availability as the key design factor.
- Set up your volumes with:
- Volume 1 Boot volume mirrored
- Volume 2 Data volume mirrored
- Volume 3
- Additional mirrored volumes as needed
NOTE: You may have non-mission critical data on the server. Create Standard or Striped volumes to hold that data. Examples are image archives, reference material, applications, fonts, etc.
NOTE: Many users prefer to have a booting Standard volume. There are a couple different ways to accomplish this, but a common one is to create a mirrored volume for booting, then after everything is set up, configured and working, "split the mirror" with SoftRAID, and leave the secondary volume as an emergency backup copy of your system volume. This setup has the advantage of preventing data downtime from system volume corruption. The trade-off is your system will crash if your primary drive fails.
WorkGroup Server - performance sensitive
Many servers are not strictly mission critical, but need the highest performance. Striping is preferred. We prefer a standard or mirrored volume (see split mirror capability as noted above) for booting and keeping only data on the striped volume. This is particularly desirable for database servers, heavy non-mission critical Appleshare IP servers, etc.
Set up your volumes with:
- Volume 1 Boot volume (Standard or "split mirror")
- Volume 2 Striped volume
- Volume 3
- Additional mirrored volumes as needed
WorkGroup Server - mixed applications
A mix of volume types is one of SoftRAID's greatest strengths. A mix of striped/mirrored volumes will optimize mission critical/performance requirements. The FIRST volume on a set of disks is the fastest volume, by up to 50% as compared to the last volume created on a set of disks.
Digital Video/Audio Capture
Digital Video has a specific application profile. The SoftRAID standard setup is simple, but customization can fine tune performance to give improved throughput.
TIP: Turn your Disk Cache down to a minimum. Disk Cache speeds up smaller I/O, but slows down sustained throughput. Set Mac OS Disk Cache to 96K.
Set up your volumes with:
- Boot drive - get a separate boot disk from your array!!!
- Volume 1 Striped for capture
- Volume 2 Striped for editing/storage
- Volume 3, 4, etc. as appropriate
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SoftRAID Customization
Desktop - Prepress/Photoshop
The goal is to get the fastest possible general purpose disk setup. Below are a few tips. SoftRAID's High Performance tips has more information.
Set up your volumes with
- Volume 1 Striped Photoshop main (fastest volume)
- Volume 2 Striped Photoshop scratch
- Volume 3 Mirrored critical data
- Volume 4 Startup volume (G4 and Blue-White G3 users, create a small standard boot volume, or boot from IDE drives)
Keep Disk Cache normal, although Photoshop will run a little faster with cache minimized.
Virtual Memory should be OFF. If you use Photoshop 3 or 4, turn Photoshop acceleration on in the SoftRAID driver. NOTE:SoftRAID is not currently able to accelerate Photoshop 5.
Set up two separate Photoshop scratch volumes, which you can erase on a regular basis. This will help improve performance of disk intensive filters.
One Photoshop tip:
Delete your preference file, then set up Photoshop exactly as you like it. Then save a copy of the preference file. Restore this "backup" preference file on a monthly basis to keep optimal Photoshop performance.
High End Desktop
SoftRAID is pre-optimized for desktop usage.
Definition of Mirrors, Stripes, Standard Volumes
SoftRAID handles disks, a partitions, and volumes very differently.
Disks
A disk drive, is a physical data storage device. A disk can be divided into logical sections called PARTITIONS. One or more partitions make up a VOLUME. SoftRAID defines disks as random access, block mapped devices which respond to the SCSI "inquiry" command with a device type of "disk". This includes most removable media devices and some optical disks.
Although SoftRAID will work with removable media, removable devices are not recommended for use with SoftRAID, as SoftRAID does not auto-mount volumes.
Volumes and Partitions
Each disk icon on the Macintosh desktop represents a volume. A partition is the region of a disk used to create a volume. A standard Macintosh volume is created from a single partition. With SoftRAID, a volume does not always represent one partition on a hard disk.
For example, a SoftRAID mirrored volume is created from two partitions on two disks; one partition is the primary and the other partition is an identical "mirror image" on another disk. A SoftRAID striped volume uses two or more partitions, each on a separate disk, to create a volume equal to the total of the combined individual partitions.
SoftRAID can create four different kinds of volumes:
- Standard MacOS
- Mirrored (RAID level 1)
- Striped (RAID level 0)
- Weighted stripe (RAID level 0)
SoftRAID is able to take an existing HFS volume and build a Mirrored or Striped volume, if an additional disk (of sufficient size) is available for building the new SoftRAID volume.
Standard MacOS Volume
An "HFS" or Standard volume is the familiar MacOS volume icon that appears on your desktop. A standard volume is made from a single partition. Standard MacOS partitions created with SoftRAID are identical to those created with Apple's Drive Setup program or any MacOS disk formatting software.
Mirroring (RAID level 1)
A mirrored volume is created from two equally sized partitions located on two different disks. One partition is called the primary and the other is the mirrored partition. The primary and mirrored partitions of a mirrored volume are kept synchronized by SoftRAID. Should a disk, cable, or SCSI adapter failure render data on one partition inaccessible, the SoftRAID program directs the system to read and write to the other partition, transparently and without interruption. All Read I/O requests from the operating system are sent to the primary partition, if available. Write I/O requests are sent to both the primary and mirror partitions. If a failure occurs, the SoftRAID Monitor extension beeps and flashes the SoftRAID icon on the Apple/MacOS Menu bar.
Status of Mirrored Volumes
SoftRAID describes the status of a mirrored volume as:
- Optimal
- Failed
- Rebuilding
NOTE: SoftRAID allows you to build a mirrored volume from a standard HFS volume without erasing the contents of the existing standard volume. This enables the addition of fault tolerance by adding a second disk. To build a mirrored volume, unmount the primary partition. To create a mirrored volume from a startup volume, startup your computer using another disk or a MacOS System software CD.
Striping (RAID level 0)
Striping spreads data across two or more equal sized partitions. A striped volume can improve performance of the array, as well as increase the contiguous storage capacity to create a single large volume. A striped volume is not redundant. If a single disk of a striped volume fails, all data on that volume is lost. Files stored on a striped volume are written on multiple disks. The SoftRAID driver automatically distributes the file data as segments when the file is written, and puts them together when the file is read. Applications on a striped volume function the same as they do on a normal HFS volume. There are many ways to optimize and improve striping performance. See Advanced Techniques for advice about optimizing or tuning a striped configuration. A striped volume does not mount unless all the partitions for that volume are present at system startup. If a partition is missing, the volume has a status of "Partition Missing". If the missing partition(s) become available later, the volume can then be mounted using SoftRAID.
Weighted Striping (RAID level 0)
Weighted Striping is ONLY available on a Macintosh with dual SCSI buses (one internal, and one external) or on an Internal 10MB/s bus, used with a PCI card SCSI bus.
Weighted striped volumes have two partitions on two different SCSI buses which are unequal in performance (for example, 5 MB/second and 10 MB/second buses or 10 MB/second and 20 MB/second buses). When creating a weighted partition, the drive on the faster SCSI bus is allocated twice as much space as the drive on the slower SCSI bus. Since a weighted stripe places twice as much data on the faster SCSI bus, performance is balanced to achieve overall improvement in the striped array. It is preferable to stripe across two PCI Wide drives than to use weighted striping. Weighted striping provides a modest performance gain over a single drive on a faster bus.
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SoftRAID Volume/Partition Limitations
SoftRAID has a few limits when creating partitions and volumes:
Partitions: SoftRAID will allow a striped volume with up to 16 partitions per volume. SoftRAID will create a maximum of 16 partitions per disk.
Volumes: SoftRAID uses a shared memory model, which limits the number of volumes created to leave room for rebuilding mirrors, etc. This limit is affected by the type of volumes created, but should be sufficiently large.
HFS volumes - SoftRAID will allow in excess of 64 HFS volumes.
Mirror volumes - SoftRAID will allow in excess of 64 Mirror volumes.
Striped Volumes - SoftRAID will allow approximately 40 two drive Striped volumes. Large stripe sets, limits drops.
For example, 16 drive striped volumes, will have a limit of around 8 volumes.
Taking Over Existing Drivers and Volumes
SoftRAID is unique in its ability to inherit existing volumes created from different drivers, even different RAID drivers. Existing servers using any of the following RAID drivers, will be instantly converted to SoftRAID volumes.
Remus, by Trillium Research (Adaptec)
- Joule RAID, by Trillium Research (Adaptec)
- Anubis RAID, by CharisMac
- RAID Toolkit, by FWB HDT 2.5 FWB
Older versions of SoftRAID and variants by Conley
- SoftRAID 1.2 or 1.5, by Conley
- Apple's RAID 1.0 and later, obtained from Apple
- Image RAID, obtained from Pathlight
- RAIDware, obtained from Hammer Storage
In addition, SoftRAID can "take over" almost any standard driver, from Silver Lining to Drive Setup. Sometimes there is not enough partition space on the drive, in which case SoftRAID will attempt to shrink existing partitions to create space. If it is unable to do so, disk will need to be initialized in order to install the SoftRAID driver.
NOTE: Some utilities, such as Norton Utilities and Tech Tool Pro install an invisible file at the end of a volume. SoftRAID cannot "shrink the volume" in such a case. If you are having problems, use a program which can read invisible files such as ResEdit or Norton Anti Virus to delete them.
- Instructions for taking over a standard driver:
- Launch SoftRAID 2.2.2
- Inspect the disk column for suitable disks to "take over"
- Highlight the desired disk
- From the Disks Menu, select "Install Driver"
- Repeat as necessary
- Restart to activate the driver
Taking over an existing RAID driver is almost identical barring a few exceptions:
Remus RAID volumes: To take over any Remus volumes, install the driver on each disk. After installing SoftRAID, you can eliminate the Remus extension, and the volumes will be fully bootable as standard Mac OS volumes.
NOTE: IF YOU ARE USING REMUS "FULL" WITH RAID 4 or 5, DO NOT INSTALL SOFTRAID ONTO ANY DRIVES.
FWB HDT and RTK volumes: SoftRAID does not "take over" the newer HDT drivers, but will take over all 2.5 or earlier HDT RAID volumes. SoftRAID must be installed onto all drives controlled by FWB. If you are using encrypted drivers, SoftRAID will take over simple encryption, exposing the data for anyone to read. If you are using "level 2" encryption, DO NOT attempt to take over, as you will end up with a volume of encrypted data that is unrecoverable.
When installing SoftRAID onto HDT 3.x and 4.x RAID drivers all volumes become unavailable. If you reinstall the HDT driver onto the FWB controlled disks and restart the volumes will be intact.
Anubis RAID volumes: SoftRAID should be installed onto all drives controlled by the Anubis drivers.
WARNING: If you have RAID volumes created by ATTO (Express RAID), MicroNet (Disk RAID), LaCie (Silver Lining Pro RAID), Formac (ProRAID) or other unlisted RAID Software drivers, do not install the SoftRAID driver onto those drives without backing up first.
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