Pegasus R6 RAID5 read only

  • Last Post 05 March 2019
Henrikas Paukstys posted this 15 April 2018

After security update Mac OS Sierra 2018-002

when i boot my mac i get an error dialog popping up saying:

os x can’t repair the disk “raid.” you can still open or copy files on the disk, but you can’t save changes to files on the disk. back up the disk and reformat it as soon as you can.

i can browse the pegsaus drive fine, all the files seem to be there as far as i can see. but i can't write to it. promise utility shows no problems at all with any of the physical drives for some reason my mac thinks there's something wrong with it, but as far as i can see it's completely fine.

Have one physical drive on slot6 (stand alone from RAID5) it mounts perfectly. I think should shut down the pegasus before installing simple security updates on my iMac, but I just forgot to shut it down.

Now copying all data from RAID, to make a format on RAID partition, but what can I do to prevent from this bug again?

Restored my iMac form backup (without this issue), but RAID5 partition again - read only. Can not repair permissions. Why this happened. Please comment

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Raghuraman Kannan posted this 17 April 2018

Hi Henrikas,

This looks to be a File system issue  as the MAC is not able to write any new contents to it. As you said the Pegasus hardware is fine and all the drives show up fine.

I would recommend you to take the backup of the data as soon as possible and then we can delete and re-create the disk array.

Thanks !

Bill Hertha posted this 05 March 2019

I am having a similar problem:

1. my RAID5 Pegasus 1 R4 drive drops into read-only some time after booting

2. the drive has two partitions, but only one becomes read-only. The other remains read-write

3. I have Pegasus 2 & 3 drives and they seem unaffected (at least to this point)

Rebooting usually resolves the problem. Sometimes it taks a couple of boots.


macOS Mojave, v 10.14.3 (18D109)

iMac Retina 5K, 27-inch, late 2014
Processor 4 GHz Intel Core i7
Memory 32 GB 1600 MHz DDR3
Graphics AMD Radeon R9 M295x 4096 MB