Interesting Issue - Pegasus 2 R6 - Drive on way out.

  • Last Post 05 July 2018
Gareth Wignall posted this 04 July 2018

So I had my R6 set up as follows:

  • PD1 - RAID 5 (LD 0)
  • PD2 - RAID 5 (LD 0)
  • PD3 - RAID 5 (LD 0)
  • PD4 - RAID 0 (LD 1)
  • PD5 - RAID 0 (LD 2)
  • PD6 - SPARE

Running latest divers, utility and firmware via MacBook Pro/27" Thunderbolt Screen, High Sierra (10.13.5)


System started going super slow and PD 4 started having minor errors (timeout). Saw somewhere that by shutting system down and then removing faulty drive would speed up system. Which it did. Unfortunatly PD 5/LD 3 was is now listed as Offline too?


Shut system down and replaced PD 4. On start up 'Major error on LD 1 & 2. "Logical drive has been placed offline. Possible Data Loss.


Now in PD List, all green lights on:

  • PD1 - Arry0 No.0
  • PD2 - Arry0 No.1
  • PD3 - Arry0 No.2
  • PD4 - PassThru
  • PD5 - Arry0 No.4
  • PD6 - Arry0 No.3


What should I do?

Would like:

  • PD 6 to revert back to being a spare.
  • PD 5 to retreve data
  • Use PD 6 to build a replica of PD 4.
  • Install a new drive to replace faulty PD 4.

Thank you for your help.


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Pradeep Chidambaranath posted this 05 July 2018

Hi Gareth,

According to first list of dirves shows PD4 and PD5 has been configured with individual RAID0 Logical Drives and PD6 was configured as a Spare drive. The second list shows PD4 shows as passthru as you have already replaced the faulty drive. PD6 is a part of Array0 Seq3 as the rebuilding has been started on the spare drive.PD5 shows Array0 Seq No.4.

As per the first list of drives, PD5 was configured as an individual RAID0 Logical drive. Did you try to delete and recreate the Logical Drive?

PD6 can be reverted as a spare drive only if the drive is configured as a revertable global spare, if it was configured as a global spare, then the drive will not be reverted as a Spare drive.

Could you please go to to create a support ticket with your phone number and the lastest report for further investigation.

Follow the below step to save the subsystem report for further investigation.

- Open Promise Utility.
- Click subsystem information icon on the top of the window.
- Click the lock symbol in the left bottom corner of the screen to unlock the utility.
- Click on save service report button to save the subsystem report.

Go to the below link to access the KB link to get the step by step instruction on how to upload the files to the support case.

Pradeep C

Richard Oettinger posted this 05 July 2018

Hi Gareth,

You used PD1 - 5 for one Disk Array (Arry0), then added one RAID5 and two RAID 0 Logical Drives.

The LDs will be stripped across the five PDs in the Disk Array, not assigned to individual PDs.

So, if a PD fails and a rebuild occurs, LD0 - the RAID5 - will be rebuilt because parity data is available, BUT the two RAID0 LDs do not have any parity data present (RAID0 = no RAID redundancy) so they can NOT be rebuilt.

Also, removing that PD would take both RAID0 LDs offline for the very same reason - no parity is available for data recovery...


Gareth Wignall posted this 05 July 2018

Hi Richard,

Promise Support are investigating further.

I thought I used PD4 & PD5 effectivly as a RAID 1/ a mirror of each other via Carbon Copy Cloner. I accepted that one drive would fail at some point (which it did,) I wasn't expecting that when one was removed, the other would be forced offlline too. 

So moving forward I would be better to set up:

  • PD1 - 5 for one disk array, then add one RAID 5 and one RAID 1 Logical Drives, PD 6 global reverting spare.


  • PD1 - 3 for one disk array RAID 5 Logical Drive, PD 4 - 5 for a second disk array RAID 1 logical drive, PD 6 global reverting spare.


  • PD1 - 3 for one disk array RAID 5 Logical Drive, PD 4 a second disk array RAID 0 logical drive, PD 5 a third disk array RAID 0 logical drive, PD 6 global reverting spare.

Your feedback would be greatly recived.


Richard Oettinger posted this 05 July 2018

A reasonable assumption, but most people dont have a clear understanding of the relationship between Disk Arrays and Logical Drives. There is a bit of voodoo involved. 8^)

Your second option would be a good one, but third would allow the most flexibilty.

Use CCC to keep LD 1 (PD4) and LD 2 (PD5) synched...

Gareth Wignall posted this 05 July 2018

Thank you.  "Life long learning." :-)

Everything is backed up elsewhere, so can format all drives currently in R6. (replacing the faulty drive.)


So what is the best way to change from current setup to future setup?

Richard Oettinger posted this 05 July 2018

You have to use the Promise Pegasus Utiity to delete the exsiting Disk Array, then create your three new DAs and their Logical Drives. Should take five minutes. Dont forget to create the Global Revertible spare...

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