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USB3 full backup slow to the point of unusable

dsnpevl
Virtuoso

Re: USB3 full backup slow to the point of unusable

I had hoped to get a bit closer to the potential 5gbps (640 MB/s) that USB 3.0 promises, even with CPU factor and other overhead. When upcoming 6.5.0 release becomes available, I will measure throughput on RN516 (with faster CPU as RN312) also.

 

Message 51 of 58
StephenB
Guru

Re: USB3 full backup slow to the point of unusable


@dsnpevl wrote:

I had hoped to get a bit closer to the potential 5gbps (640 MB/s) that USB 3.0 promises, even with CPU factor and other overhead. When upcoming 6.5.0 release becomes available, I will measure throughput on RN516 (with faster CPU as RN312) also.

 


 

USB 3.0 has a link speed of 5 gbps, but each byte is encoded as 10 bits, so the raw transfer speed is 500 MB/s, not 640.  However, there is overhead in the protocol, and the theoretical transfer speed limit with 3.0 for disks is 450 MB/s.

 

USB 3.1 Gen-2 has a link speed of 10 gbps and lower overhead.  A USB Gen-2 drive has a theoretical transfer speed limit of 1.1 GB/sec.  

 

But in the real world, if you are using a mechanical USB 3.0 drive, your top speed is limited by the drive - usually around 125 MB/sec in a typical  3.5" USB 3.x drive. Even if you use fast SSDs/flash, the fastest USB speeds I've seen in reviews is ~400 MB/sec.  Getting 95 MB/sec speeds in a ReadyNAS with NTFS is really very good, esp. since NTFS isn't a natively supported file system for linux.

 

http://www.everythingusb.com/speed.html

 

 

FWIW ReadyNAS USB ports are spec'ed as USB 3.0 (if they do support USB 3.1 Gen-2, it's not on the the datasheets).

Message 52 of 58
dsnpevl
Virtuoso

Re: USB3 full backup slow to the point of unusable


@StephenB wrote:
Getting 95 MB/sec speeds in a ReadyNAS with NTFS is really very good, esp. since NTFS isn't a natively supported file system for linux.

Thnx for explaining the technical details!

I'll adjust my expectations accordingly.

Message 53 of 58
dsnpevl
Virtuoso

Re: USB3 full backup slow to the point of unusable


@dsnpevl wrote:

I will measure throughput on RN516 (with faster CPU as RN312) also.


Achieved 93 MB/s on RN516 with RC2 (during daytime with medium load). Nightly scheduled backup should be a bit faster.

Message 54 of 58
Michael_Oz
Luminary

Re: USB3 full backup slow to the point of unusable


@mdgm wrote:

Thanks for your patience.

There is a fix in ReadyNASOS 6.5.0 (RC2). The production 6.5.0 firmware is currently expected to be released early/mid May.


Is there any update re early/mid?

Message 55 of 58
StephenB
Guru

Re: USB3 full backup slow to the point of unusable


@Michael_Oz wrote:


Is there any update re early/mid?


RC3 was released yesterday.  I have no inside info (I don't work for Netgear), but I'd expect this to be the last beta - unless they find something unexpected that simply has to be fixed.

Message 56 of 58
kohdee
NETGEAR Expert

Re: USB3 full backup slow to the point of unusable

One of the newer RC builds (2 or 3) should have an enhancement using NTFS. 

Message 57 of 58
mdgm-ntgr
NETGEAR Employee Retired

Re: USB3 full backup slow to the point of unusable


@kohdee wrote:

One of the newer RC builds (2 or 3) should have an enhancement using NTFS. 


Yes it is in RC2.

Message 58 of 58
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