Thank you for purchasing through links and ads on this site.
OWC / MacSales.com...
diglloyd Deal Finder...
Buy other stuff at Amazon.com...
Upgrade the memory of your 2019 iMac up to 128GB
PLEASE buy at B&H via this site to support Lloyd’s reviews!
B&H Photo PAYS THE SALES TAX FOR YOU More info...

Promise Pegasus J4 — Initializing Volumes

Last updated 2013-07-03 - Send Feedback
Related: backup, RAID, RAID-0, SSD, storage, Thunderbolt

Update: see issues.

The 4-bay Promise Pegasus J4 is available as 0GB solution (you supply the drives) or a 2TB (4 X 500GB) solution.

The Pegasus J4 acts as a HBA (host bus adapter), so up to four drives can be installed into it, and each hard drive or SSD appears separately in Disk Utility.

That flexibility can be very useful, but it does not include high performance and fault tolerant hardware solutions such as RAID-5 (striping with parity). However, RAID-1 mirroring can be used, or with some low-level configuration effort at the command line, RAID 0+1 (a mirror of stripes).

Example drive install

Shown below, four OWC Mercury Elite Pro 6G SSDs are installed in the Pegasus J4 (cover is removed for the photo). Since each of these drives is by itself a very high performance device, a setup like this is a very high performance arrangement.

As shown, these are 240GB SSDs, but they could just as well be 120GB or 480GB units, capacity being the question.

Possible ways to configure them include:

  • 4 X 240GB RAID-0 stripe producing ultra high performance 960GB volume.
  • Two pairs of 2 X 240GB RAID-0 striped drives (480GB each volume).
  • Two pairs of 2 X 240GB RAID-1 mirror drives (240GB each volume).
  • Four separate 240GB volumes.
  • 3 X 240GB = 720GB RAID-0 stripe + one 240GB volume.
Fast and cost effective way to backup!

How about a 3-drive stripe + 4th drive for clone backup?

That last 3-drive stripe configuration is interesting: a 3-drive stripe provides essentially the same performance as a 4-drive stripe due to the Thunderbolt bus speed limit.

One could instead make that 4th drive a high capacity 2.5-inch 9mm-thick hard drive which serves as a backup clone of the 3-drive stripe (or Time Machine backup). This is not the same as RAID-5 striping+parity, but it achieves a similar reliability goal.

Promise Pegasus J4 with 4 X OWC Mercury Extreme Pro 6G SSD

Initialized as single drives

Here the four OWC 6G SSDs I installed were initialized as separate volumes d1/d2/d3/d4, as shown.

There are reasons to do this, namely to provide separate chunks of space (volumes) for different projects that do not need ultra high performance and are better off not taking the increased failure risks of RAID striping.

Promise Pegasus J4 with 4 X OWC Mercury Extreme Pro 6G SSD initialized singly

Initialized as a single volume — 4-way RAID-0 stripe

Here the four OWC 6G SSDs I installed were initialized as a 4 X 240GB RAID-0 stripe, producing a 960GB single ultra high performance volume.

Promise Pegasus J4 with 4 X OWC Mercury Extreme Pro 6G SSD initialized as 4-way striped RAID-0

MacPerformanceGuide.com
B&H Deal ZoneDeals by Brand/Category/Savings
Deals expire in 4 hours unless noted. Certain deals may last longer.
$1089 SAVE $610 = 35.0% $16 FREE ITEMS Canon 18x50 IS Image Stabilized Binocular in All Other Categories
$2797 SAVE $600 = 17.0% $246 FREE ITEMS Nikon Z 7 Mirrorless in Cameras: Mirrorless
$649 SAVE $250 = 27.0% $6 FREE ITEMS Sigma 35mm f/1.4 DG HSM Art in Lenses: Mirrorless
$2598 SAVE $600 = 18.0% Sony a7R III Mirrorless in Cameras: Mirrorless
$3498 SAVE $1000 = 22.0% Sony a9 Mirrorless in Cameras: Mirrorless
$898 SAVE $100 = 10.0% $145 FREE ITEMS Sony DSC-RX100 VA in Cameras: Point and Shoot
$1329 SAVE $170 = 11.0% ZEISS 18mm f/2.8 Batis in Lenses: Mirrorless
$1169 SAVE $130 = 10.0% ZEISS 25mm f/2 Batis in Lenses: Mirrorless
$1169 SAVE $130 = 10.0% ZEISS 40mm f/2 Batis CF in Lenses: Mirrorless

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2019 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__