256GB Lexar 1066X CF Card incompatible? Video Attached

[Wilson WONG]

Camera:5D Mark iii
Firmware:1.1.3
Danne's Build:https://www.magiclantern.fm/forum/index.php?topic=23041.0
CF Card:Lexar 256GB 1066x
Problem: 256GB Card has extremely low write speed around 6.5mb/s while 64GB CF card work well
(PS:the 256GB card has been formatted by mac disk utility and tested by Blackmagic Disk speed test app)

Blackmagic Disk speed test snapshot
https://drive.google.com/file/d/1qgNRt0cND3HMBIZ4_3wvQwWnoi6nYSlO/view?usp=sharing

The problem is described in detail in the video below

Can anyone help me ?

[Walter Schulz]

Modules tab -> activate bench.mo
Restart cam in photo mode
Access Debug tab ->  Benchmarks -> Card benchmarks -> Quick R/W benchmark (1 min)

Cam will write results as BENCHx.PPM to card.
Proceed benchmark for both cards and post results.

[Bruno Italiano]

Dear friend,
I would guess, CF cards over 64GB are in a different data format. This should be formatted in ExFat. Are you sure you formatted the card in the camera before you recorded?

Your Bruno  x

[Wilson WONG]

Modules tab -> activate bench.mo
Restart cam in photo mode
Access Debug tab ->  Benchmarks -> Card benchmarks -> Quick R/W benchmark (1 min)

Cam will write results as BENCHx.PPM to card.
Proceed benchmark for both cards and post results.

Thanks and here's the result
https://drive.google.com/file/d/1m3yqIAMkQ5Zpd3x_IoimYUiG6exhimeh/view?usp=share_link

64GB:
Benchmark complete.
ets) tiply. 2022Dec02.5D3113. 6c65806f1ee2+ (crop_rec_4k_mIv_
Mode:
PLAY-PH LCD, Global Draw: OFF
Write speed (buffer =16384k):
Read speed
(buffer=16384k）：
Write speed (buffer =16384k):
Read speed (buffer =16384k):
66.4 MB/s
72.1 MB/S
64.0 MB/S
72.0 MB/s

256GB:
Benchmark complete.
ets) tiply. 2022Dec02.5D3113. 6c65806f1ee2+ (crop_rec_4k_mIv_
Mode: PH-LV LCD, Global Draw: OFF
FF IFXAR ATA FIASHCARD
Write speed (buffer =16384k):
Read speed (buffer=16384k):
Write speed (buffer =16384k):
Read speed (buffer =16384k)
6.6 MB/s
6.4 MB/s
6.6 MB/S
6.4 MB/S

[Wilson WONG]

Dear friend,
I would guess, CF cards over 64GB are in a different data format. This should be formatted in ExFat. Are you sure you formatted the card in the camera before you recorded?

Your Bruno  x

God!!! Thanks Bruno  ! Got the point!
This is the result after formatted in the camera! And all is well again!!
Benchmark complete.
ets) tiply. 2022Dec02.5D3113, 6c65806f1ee2+ (crop_rec_4k_mIv_
Mode: PLAY-UNK LCD. Global Draw: OFF CF LEXAR ATA FLASH CARD LEXAR ATA FLASH CARD
Write speed (buffer =16384k):
118.8 MB/s
Read speed (buffer =16384k):
Write speed (buffer =16384k):
151.1 MB/s
117.5 MB/s
Read speed (buffer =16384k):
151.2 MB/s

[Wilson WONG]

So sorry that I've make a mistake!  I think the 'successful data' is from my old 64GB card .After formatting my 256GB card in the camera, the problem is still here.

[Walter Schulz]

I have troubles making sense of it.

Test 1:
Format card on PC using NTFS or any other file format the camera can't handle.
Insert card into camera. You will be prompted to format the card. Do so. Now try to record a video with Canon's native codec. Try 1080p30 with ALL-I. This should give you a write rate around 11 MByte/s. Are you able to record a full session = 29:59?

[Wilson WONG]

Thank you for your test advice, Walter! I  sincerely follow your instruction to do the test and make it into a video.
Not a valid youtube URL[/youtube]

However, the result is quite...as you said, it dosen't make any sense!

Merry Christmas!

[Wilson WONG]

[Walter Schulz]

Can't see if you used ALL-I or IPB.
That's why I asked about ALL-I: IPB goes with around 5.5 MByte/s on average and should not get into buffer underrun issues. ALL-I averages at around 11 MByte/s.
You may calculate data rate by (File sizes summed up for a 29:59 session)/1800 seconds.

[Wilson WONG]

It is ALL i , timeline around 33:15 can be seen clearly.
However, you've enlighten me to do another test.

(BTW, the video was originally filmed for the seller to explain something wrong with his product, so I didn't use English😂)

Do you think it can improve that it is the card's problem?