ESOS 4.4.1 (SCST 3.9.0) don't support lb_per_pb_exp vdisk attribute

[inbusine...@gmail.com]

Hi!

I completed new ESOS 4.4.1 that include SCST 3.9.0.

SCST 3.8.0 include vdisk_io attribute "lb_per_pb_exp=0" like belows.

https://github.com/SCST-project/scst/releases

https://github.com/SCST-project/scst/pull/136

lb_per_pb_exp option equal to TrueNAS Scale - that use same SCST target - extent option like below.

TrueNAS Scale's SCST 3.8.0 support above option that include SCST 3.8.0 or above.

But your ESOS 4.4.1 SCST 3.9.0 don't support lb_per_pb_exp option.

Could you check it again?

Best Regards,

Jae-Hoon Choi

[Marc Smith]

Yes, it uses SCST 3.9.0 and that version of SCST includes the "lb_per_pb_exp" sysfs attribute for vdisk_blockio SCST devices; try using "ls -ltr /sys/kernel/scst_tgt/devices/lun011/" to see the attribute.

--Marc

 

Best Regards,

Jae-Hoon Choi

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[inbusine...@gmail.com]

Thank you for your quick respond...:)

I made a 1MB zvol "lun011" then add a parameter lb_per_pb_exp=0 like below

echo 0 > /sys/kernel/scst_tgt/devices/lun011/lb_per_pb_exp

That will help to make a VMFS6 datastore for ESXi 8.0.3 that use 1MB partition block.

Whenever try create VMFS6 ESXi datastore without  lb_per_pb_exp=0 option with above 64KB block zvol will meet a error message.

Thank you so very much!

I made a Ethernet iSER target for home lab that show me a perfect performance...:)

Best Regards,

Jae-Hoon Choi 

[inbusine...@gmail.com]

Hi!

I found another configuration method like below

echo 0 > /sys/kernel/scst_tgt/devices/lun011/lb_per_pb_exp

I'm also use this format for VMware VAAI 

echo SCST_BIO > /sys/kernel/scst_tgt/devices/lun011/prod_id

That'll erase problem that ESXi don't accept to create datastore with zvol 128KB or above block size.

I made a iSER target for my homelab block storage with 1MB block size zvol datastore for ESXi server.

High block size will affect massive data transfer.

Previous SCST 3.8.0 was not support what I want block storage.

Thank you for your all kind support.

I'll build a next storage target with NVMe over RDMA...:)

Regards,

Jae-Hoon Choi

On Thursday, June 26, 2025 at 9:51:27 PM UTC+9 Marc Smith wrote:

[inbusine...@gmail.com]

Yes!

I can found that parameter with your sample command like below.

I made lun011 with commands like below.

scstadmin -open_dev lun011 -handler vdisk_blockio -attributes filename=/dev/storage/lun011,thin_provisioned,nv_cache=0,rotational=0,blocksize=512

When if input command scstadmin -open_dev lun011 -handler vdisk_blockio -attributes filename=/dev/storage/lun011,thin_provisioned,nv_cache=0,rotational=0,blocksize=512,lb_per_pb_exp=0 that will accept parameter lb_per_pb_exp=0.

Is there any command option in CLI?

Regards,

Jae-Hoon Choi

On Thursday, June 26, 2025 at 9:51:27 PM UTC+9 Marc Smith wrote: