Esxi migration starts fast then becomes really slow.

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frapel25

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Dec 5, 2025
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Hello,
I have just installed proxmox on a dell r730 with a h730mini controller and 2 ssds in hba mode.
I am trying to migrate few esxi vms but it is almost impossible.
Some vms start the migration, proxmox starts copying quite fast but then half way the speed decreases dramatically, from 400mb/s to 1-5mb/s. It took 2 hours for a 50gb vm. Other vms get stuck at 0% copy for hours. Meanwhile proxmox becomes unresponsive and it is very difficult to open the web interface. The ssds are from transcend and have a dram chip.
What could be the problem? If I change the storage to my hdd nas it looks like the speed remains steady, got 10 min for 50gb vms.
Thank you for any help!
 
frapel25 said:
They are transcend 230s, from the specs I read Dram and SLC.
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All (which size did you get?) of the Transcend 230S are 3d v-nand (TLC) as far as I can tell. Where did you get the information about them being SLC? Either way, they are not as bad as QLC but they are not as good as enterprise SSDs with PLP. Getting a write slow down is not uncommon (when the cache runs out) but there might be something else causing the issue you see. Maybe someone else knows?
 
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I read it on Transcend website. In the next days I will try putting an ssd with proxmox on another server in order to see if it might be due to the h730 for example, I hope not.
 
frapel25 said:
I read it on Transcend website.
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Can you be more specific? The general website ( https://www.transcend-info.com/Products/No-756 ) only mentions SLC cache. Many SSDs use part of the flash memory as SLC for short writes and then rewrite it to TLC or QLC. It looks like you bought consumer drives for a clustered enterprise hypervisor and it's no surprise that they don't perform great, but they do work and might be good enough for some (or maybe even most) purposes. With your drives, I would learn to live with some (extreme) write slowdowns, and as long as the IOPS for running VMs is fine (and I have proper backups), life is good (enough).

EDIT: Nobody makes SLC drives anymore, even MLC are rare. But everyone repurposes part of their TLC and QLC memory as SLC cache.
 
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Well, I simply read dram and slc, I thought they would perform better than this. I have Samsung 870 evos in other servers and this has never happened before. It’s not mandatory to use these drives I can just send them back and grab something else. It will be a production environment so i’d better buying something else. Is there any data ssd you could suggest? Do you think a 870 evo could solve the problem? Thank you!
 
frapel25 said:
WIt will be a production environment so i’d better buying something else. Is there any data ssd you could suggest?
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Migration of VMs is something you do only once, so if it's good enough (or not too bad) then it does not matter too much. Test you regular VM work-load with your current system and only then decide on spending money. As I said before, lots of threads about SSD and enterprise drives that provide Power Loss Protection (PLP) that can cache sync writes. Just search for enterprise and PLP.
 
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Dear God, you want to put a consumer Evo drive in a production server?? You wouldn't be working on my team for long.

https://search.brave.com/search?q=2,5+inch+enterprise+ssd+for+proxmox&summary=1&conversation=5b3653a7fd182a09655e79

I hope you have at least bought proxmox licensing and support, they should be able to recommend stuff for decent builds.

Edit: Transcend has an "enterprise" link right down there at the bottom of the page:

https://www.transcend-info.com/embedded/product/enterprise-ssd-solutions/etd210t

https://www.cdw.com/search/storage-hard-drives/solid-state-drives/?lfr=1&w=KE&key=transcend+ETD210T
 
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