VM Backups over Transport Type = SAN is slow,better Transport Type = nbd

Hi guys 

please help me whether any problem from my configuration 

why backups vm with transport SAN is slow better transport ndb this the detail status backup :

Over SAN 

May 12, 2017 5:00:53 PM - Info nbjm (pid=10184) starting backup job (jobid=25320) for client 10.148.148.201, policy vm_fs1, schedule full
May 12, 2017 5:00:53 PM - estimated 0 kbytes needed
May 12, 2017 5:00:53 PM - Info nbjm (pid=10184) started backup (backupid=10.148.148.201_1494583253) job for client 10.148.148.201, policy vm_fs1, schedule full on storage unit Dedupe_STU using backup host mjtbackup.mjt.app.com
May 12, 2017 5:00:54 PM - Info bpbrm (pid=6048) 10.148.148.201 is the host to backup data from
May 12, 2017 5:00:54 PM - Info bpbrm (pid=6048) reading file list for client
May 12, 2017 5:00:54 PM - started process bpbrm (pid=6048)
May 12, 2017 5:00:54 PM - connecting
May 12, 2017 5:00:55 PM - Info bpbrm (pid=6048) starting bpbkar32 on client
May 12, 2017 5:00:55 PM - connected; connect time: 0:00:00
May 12, 2017 5:00:56 PM - Info bpbkar32 (pid=12240) Backup started
May 12, 2017 5:00:56 PM - Info bpbkar32 (pid=12240) archive bit processing:<enabled>
May 12, 2017 5:00:56 PM - Info bptm (pid=4784) start
May 12, 2017 5:00:56 PM - Info bptm (pid=4784) using 262144 data buffer size
May 12, 2017 5:00:56 PM - Info bptm (pid=4784) setting receive network buffer to 1049600 bytes
May 12, 2017 5:00:56 PM - Info bptm (pid=4784) using 16 data buffers
May 12, 2017 5:00:57 PM - Info bptm (pid=4784) start backup
May 12, 2017 5:00:58 PM - Info bpbkar32 (pid=12240) INF - Backing up vCenter server vcenter, ESX host 10.148.148.31, BIOS UUID 423b24a9-a027-8d7d-4a4f-c2e9a2dfe70a, Instance UUID 503bc590-9ef4-16ce-9cfa-b96c8ae0eb48, Display Name MJTFS1-3, Hostname 10.148.148.201
May 12, 2017 5:01:09 PM - begin writing
May 14, 2017 12:52:38 AM - Info bpbkar32 (pid=12240) INF - Transport Type = san
May 15, 2017 7:29:08 AM - Info bptm (pid=4784) waited for full buffer 840270 times, delayed 11476751 times
May 15, 2017 7:29:10 AM - Info bpbkar32 (pid=12240) bpbkar waited 593955 times for empty buffer, delayed 597878 times.
May 15, 2017 7:30:51 AM - Info bptm (pid=4784) EXITING with status 0 <----------
May 15, 2017 7:30:51 AM - Info mjtbackup.mjt.app.com (pid=4784) StorageServer=PureDisk:mjtbackup.mjt.app.com; Report=PDDO Stats for (mjtbackup.mjt.app.com): scanned: 1948006304 KB, CR sent: 1534887442 KB, CR sent over FC: 0 KB, dedup: 21.2%, cache hits: 575974 (2.3%), rebased: 233321 (0.9%)
May 15, 2017 7:30:51 AM - Info bpbrm (pid=6048) validating image for client 10.148.148.201
May 15, 2017 7:31:31 AM - Info bpbkar32 (pid=12240) done. status: 0: the requested operation was successfully completed
May 15, 2017 7:31:31 AM - end writing; write time: 62:30:22
the requested operation was successfully completed (0)

Over ndb

May 13, 2017 2:01:23 AM - Info nbjm (pid=10184) starting backup job (jobid=25326) for client 10.148.148.203, policy vm_fs3, schedule full
May 13, 2017 2:01:24 AM - estimated 2119934476 kbytes needed
May 13, 2017 2:01:24 AM - Info nbjm (pid=10184) started backup (backupid=10.148.148.203_1494615683) job for client 10.148.148.203, policy vm_fs3, schedule full on storage unit Dedupe_STU using backup host mjtbackup.mjt.app.com
May 13, 2017 2:01:24 AM - started process bpbrm (pid=684)
May 13, 2017 2:01:25 AM - Info bpbrm (pid=684) 10.148.148.203 is the host to backup data from
May 13, 2017 2:01:25 AM - Info bpbrm (pid=684) reading file list for client
May 13, 2017 2:01:25 AM - Info bpbrm (pid=684) starting bpbkar32 on client
May 13, 2017 2:01:25 AM - connecting
May 13, 2017 2:01:25 AM - connected; connect time: 0:00:00
May 13, 2017 2:01:26 AM - Info bpbkar32 (pid=12324) Backup started
May 13, 2017 2:01:26 AM - Info bpbkar32 (pid=12324) archive bit processing:<enabled>
May 13, 2017 2:01:26 AM - Info bptm (pid=12712) start
May 13, 2017 2:01:26 AM - Info bptm (pid=12712) using 262144 data buffer size
May 13, 2017 2:01:26 AM - Info bptm (pid=12712) setting receive network buffer to 1049600 bytes
May 13, 2017 2:01:26 AM - Info bptm (pid=12712) using 16 data buffers
May 13, 2017 2:01:28 AM - Info bptm (pid=12712) start backup
May 13, 2017 2:01:28 AM - Info bpbkar32 (pid=12324) INF - Backing up vCenter server vcenter, ESX host 10.148.148.31, BIOS UUID 423536a3-e76a-53d4-4168-f6d38fc09a6c, Instance UUID 50351418-66d6-11dd-cf96-d61edca9e060, Display Name MJTFS3, Hostname 10.148.148.203
May 13, 2017 2:01:38 AM - begin writing
May 13, 2017 3:44:35 AM - Info bpbkar32 (pid=12324) INF - Transport Type = nbd
May 14, 2017 4:17:42 AM - Info bptm (pid=12712) waited for full buffer 2866029 times, delayed 5064270 times
May 14, 2017 4:17:45 AM - Info bpbkar32 (pid=12324) bpbkar waited 121 times for empty buffer, delayed 8208 times.
May 14, 2017 4:21:01 AM - Info bptm (pid=12712) EXITING with status 0 <----------
May 14, 2017 4:21:01 AM - Info mjtbackup.mjt.app.com (pid=12712) StorageServer=PureDisk:mjtbackup.mjt.app.com; Report=PDDO Stats for (mjtbackup.mjt.app.com): scanned: 1776648238 KB, CR sent: 25803727 KB, CR sent over FC: 0 KB, dedup: 98.5%, cache hits: 267023 (0.5%), rebased: 73006 (0.1%)
May 14, 2017 4:21:02 AM - Info bpbrm (pid=684) validating image for client 10.148.148.203
May 14, 2017 4:21:32 AM - Info bpbkar32 (pid=12324) done. status: 0: the requested operation was successfully completed
May 14, 2017 4:21:32 AM - end writing; write time: 26:19:54
the requested operation was successfully completed (0)

Regards,

sigit