VMware vSphere • Re: Poor restore performance when restoring in AllFlash environment

Hi together,

Some news from the work on the support case. I did some more testing today. In summary, with a single VMDK, the fastest speed is just under 500 MB/s in hot-add mode with a 4 MB block size. When restoring multiple disks, it's difficult to say which mode is fastest.

1. Restore in Hot-Add Mode

1 MB blocksize with lazy zeroed restore
Restoring Hard Disk 1 (100 GB): 28.2 GB restored at 320 MB/s [hotadd]

4 MB blocksize with lazy zeroed restore
Restoring Hard Disk 1 (100 GB): 28.8 GB restored at 383 MB/s [hotadd]

1 MB blocksize with thick eager zeroed restore
Restoring Hard Disk 1 (100 GB): 28.2 GB restored at 392 MB/s [hotadd]

4 MB blocksize with thick eager zeroed restore
Restoring Hard Disk 1 (100 GB): 28.8 GB restored at 473 MB/s [hotadd]

2. Restore multiple VMDKs simultaneously (hard disks are restored simultaneously, Hard Disk 1 is the fastest, which is why the speed is faster towards the end)

Restore in SAN mode:
1MB blocksize with lazy zeroed
Restoring Hard disk 2 (100 GB) : 4.1 GB restored at 85 MB/s [san]
Restoring Hard disk 1 (160 GB) : 82.6 GB restored at 99 MB/s [san]
Restoring Hard disk 3 (100 GB) : 13.6 GB restored at 90 MB/s [san]

1MB blocksize with eager zeroed disk
Restoring Hard disk 2 (100 GB) : 4.1 GB restored at 156 MB/s [san]
Restoring Hard disk 3 (100 GB) : 13.6 GB restored at 174 MB/s [san]
Restoring Hard disk 1 (160 GB) : 82.6 GB restored at 266 MB/s [san]

Restore in Hot Add Mode:
1MB blocksize with Lazy Zeroed
Restoring Hard disk 1 (160 GB) : 82.6 GB restored at 338 MB/s [hotadd]
Restoring Hard disk 2 (100 GB) : 4.1 GB restored at 263 MB/s [hotadd]
Restoring Hard disk 3 (100 GB) : 13.6 GB restored at 186 MB/s [hotadd]

1MB blocksize with eager zeroed disk restore
Restoring Hard disk 1 (160 GB) : 82.6 GB restored at 338 MB/s [hotadd]
Restoring Hard disk 2 (100 GB) : 4.1 GB restored at 275 MB/s [hotadd]
Restoring Hard disk 3 (100 GB) : 13.6 GB restored at 220 MB/s [hotadd]

Statistics: Posted by MirkoKiel123 — Jul 02, 2025 9:28 am

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