Long Shot, But trying to see why I am experiencing slow downs on Pegasus32 and Browser Crashes

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  • Last Post 19 June 2026
John Felske posted this 11 June 2026

Ever sence moving from Intel Mac to Mac Studios I have run into some interesting issues that I have been unable to solve.

 

1. Speeds on Promise Pegasus32 R6 have been subpar based on the TB3 standard from what I can really gather. I at best see around 550 - 800MB/s Writes and 450 - 750MB/s Read. I almost see these similar speeds with USB-C 10Gbps. I have tried numerous cables (active and passive).

 

2. And this is a extremely weird one. (Don't have this at all when using USB-C Drives Directly) When attempting to write files to the PP32 from lets say chrome or safari, it will just end up circle of death and crash the browsers to halt, then I have to force quit, but after that I must reboot as it will just happening again sooner and sooner. 

 

I have been able to replicate this by saving indivdual files, like photos, one after another and then it will cause the halt, this could freeze the browser for 2 - 10 mins then maybe I will be able to save again to the PP32 for a few more times before it happens again and must reboot. 

 

One thing I do notice is that the process of "Open and Save Panel Service" for lets say google does fail and error out, but it seems like the system is either way too fast and cannot catch up or extremely slow. 

 

I have seen some talk about "If a RAID volume has a 16kB stripe size, it is known to cause kernel panics on M-series chips. You may need to back up your data and reformat the array using a 64kB stripe unit size (or convert to a RAID 4/5)" and wonder if there is something here on my end. 

 

I know its a long shot and a lot there, but I have been at this for a long time trying to figure this out, from M1 to M4, just seems I am having issues directly with Pegasus in general and its not happy with Apple Silicone. (Purchased a new M4 fresh out of box thinking it would solve issues and its the same thing.) 

 

Update: as of writting this, I tested brand new TB4/5 Active cables and saw same read and write speeds above. Randomly grabbed a passive TB4 Cable and seeing speeds now reach 1100-MB/s Read and 770MB/s Write which seems to be more aligned with expectations for TB3 and RAID5. Not sure why the actives are reverting to USB speeds as the run is over 3 meters, but it is interesting. 

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John Felske posted this 11 June 2026

Oh and I suppose to add a cherry on top, I also have a Pegasus32 R4 connected to the R6 and randomly it will not mount. Just decides not today and Have to unplug and reboot the R4. Its very random but honestly I am suprised more when it does mount when it doesnt.

Firmware Versions 6.06.0000.45

R P posted this 11 June 2026

Hi John,

There are a few potential sources of the slowness issue.

1. The Pegasus32 has been formatted with APFS, which is designed for flash media, it will get slower as the volume fills.
2. One drive has become slow, a RAID set is no faster than the slowest drive.

There are no known mount/dismount issues with the Pegasus32 with any version of the firmware. The most likely cause here would seem to be an intermittant cable.

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John Felske posted this 12 June 2026

Interesting, appreciate the reply. 

These are HFS+, as I would not bother with APFS on Spinners. 

One drive becoming slow is intersting. I do have some older Pegasus systems I will boot up and format to test. As I am really at a loss here. Its been over a year and back and forth with Apple for some insight, etc... I know at the time, my 27" Intel Mac didnt seem to be an issue with the same drives and system, and once I jumped over to Mac Studios, I noticed the speed issues and for sure the Web Broswers and system halting trying to save small files from browers in repetitive pattern.

I can confirm though, both my Pegasus32's (R4 and R6) don't seem to like any active TB cables lol. I have brand new ones for another project and they throttle down to 10Gbps for sure lol.

Again thanks, back to testing some more.  

John Felske posted this 15 June 2026

So I might have stumbled onto something here. 

I see that my Pegasus32 Systems are stetup with a 1 MB Stripe size and a Sector size of 512kb on a RAID 5. I pulled out an older Pegasus 2 and built out the RAID 5 to be a Stripe size of 256kb and a sector size of 4kb. I got this change based on some chat bot recommendations off other fourms (apple, etc..) and so far I am not seeing the same browers or system crashing as I was with the bigger stripe and sector size.

I also have seen a good amount of issues with SoftRAID and some OWC products and a lot of dealings with Stripe size so it got me thinking. 

Still testing but maybe this is something promising. 

Information (high level) I was getting this change from: (I am using HDD so went with Mac OS Extended Journaled

For the best balance of speed and data safety on your Promise Pegasus with an Apple Silicon Mac, the consensus among professionals is to use RAID 5. To optimize this setup for macOS, format the volume as APFS and configure the array with a 256K stripe size and a 4K sector size. [1, 2]   Recommended RAID Profile

 

  • RAID Level: RAID 5
    • Why: Offers excellent read/write speeds while providing 1-drive parity, ensuring you won't lose data if a single drive fails. [1]
  • Stripe Size: 256 KB
    • Why: The ideal middle-ground block size for sequential creative workloads like 4K/8K video editing and large file transfers. (Avoid 64K, which can bottleneck performance on larger arrays). [1, 2]
  • Sector Size: 4 KB
    • Why: This matches the native block/sector size of modern macOS APFS file systems and enterprise hard drives. [1]

John Felske posted this 19 June 2026

Never mind, this setup worked for a bit but in the end failed.

But.... I do think I found out the final issue and it is not technically fixible for my needs.

Comes down to the amount of files, raid, file system that is overloading the open/save dialog process within finder. When doing a save as or something like that to the Promise speficially, it is attemping to load every single file and meta data within that folder or structure I have setup. This is causeing the open/save and finder to beachball or crash in Chrome or even Safari. 

This doesnt happen saving to external drive like a T7 or internal drive. Its specific to the Promise. I never noticed this with Intel based Macs, but it is by far an issue with the Applie Silicone Macs like M1/M4. 

Its a bummer, but makes sense. Only way to get around this is to bypass the Save As witin the open/save feature, and directly save to a folder then sort later or do whats needed. Even then, I do see this cause errors also at somepoint. Another idea with to move to SSD and APFS and should not see as much issue maybe. However, this has its issues on its own. Also using APFS on standard HDD's is really not a good option for the long haul. 

So next steps will be to figure out a File Structure that is suitable for our needs and bypass the Open/Save feature within chrome, finder, etc... Not ideal but either is the crashing. 

Maybe this helps anyone else having simiarl issues. 

For informaiton, I have a few of these systems and they all expecerience this issue once enough files are on the systems. The main systems I am seeing issues with are Pegasus32's, one is RAID 5 72TB with 60TB useable. Other is 32TB with 24TB useable. 

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