2015-07-23, 05:19
While I was choosing the hardware to build my HTPC system and reading all about SATAIII, Gigabit ethernet and so on, I came across the question:
"How much specific hardware speed I need to stream my media, from HDD to the tv?"
I thought I could share my thoughts with you and please, tell me if it was done before, I have not found any previous thread on this topic. I have no problem in being absolutely wrong in anything stated here, as long it leads to a usefull discussion. Sorry for typos or bad english.
Put that I don't have a 4k capable tv (and I won't in the near future), I'll use as reference a theoretical FullHD video (1920x1080, widescreen), at maximum AV bitrate encoding of 48 Mbps or 6 MBps [source].
What's the path the movie's bytes take from my NAS towards my HTPC box and how much bandwidth/tranfer rate I need from my hardware?
HDD ----> [motherboard interface ----> OS] ----> network interface ----> [HTPC box]
Let's examine each device separetely:
1) HDD
Model used here:
- Seagate ST4000DM000
- 4 TB disk space, 64mb cache
As a reference, the sequential read throughtput of this HDD on a Sata III interface is 138 ~146 MB/s [source]
(One Sata III port could be shared by 5 of this HDD model)
Possible ports (ascending speed order):
- USB 1.1 - 12 Mbps or 1.5 MBps
- USB 2.0 - 480 Mbps or 60 MBps
- Ultra DMA (ATA 133) - 1064 Mbps or 133 MBps
- SATA I - 1500 Mpbs or 150 MBps (Sata uses 8b/10b encoding [source])
- SATA II - 3000 Mbps or 300 MBps
- USB 3.0 - 5000 Mbps or 625 MBps
- SATA III - 6000 Mbps or 600 MBps
Hell, even Ultra DMA ATA 133's speed (1064 Mbps / 133 MBps) would be enough to transfer the 48 Mbps stream.
2) Network interface
Ethernet:
- Fast Ethernet (100BASE-TX) - 100 Mbps or 12.5 MBps
- Gigabit Ethernet (1000BASE-T) - 1 Gbps or 125 MBps
Wireless:
- 802.11b - 11Mbps
- 802.11a/g - 54Mbps or 6.75 MBps
- 802.11n - 600 Mbps or 75 MBps
- 802.11ac - maximum theoretical speed 6.8 Gbps or 850 MBps
Considering the theoretical HDD and network interfaces speed, a NAS device capable of streaming 1080p media could be built with the minimal requirements regarding HDD interface and networking:
- HDDs connected to USB 2.0, Ultra DMA ATA 133 or SATA I ports;
- Fast Ethernet (10/100) adapter or
- Wireless IEEE 802.11a/g (or 802.11n to leave some room for overhead and other traffic)
Conclusion:
Building NAS boxes with SATA III, SSD, Gigabit ethernet or IEEE 802.11ac wireless is a waste of hardware and money, regarding only the task of moving the media from the HDD to the network. It's not taken in consideration file copy/move/download operations.
NOTE:
xbps / 8 = xBps
1 byte (B) = 8 bit
1 kbps = 1000 bit/s
1 Mbps = 1000000 bit/s
1 Gbps = 1000000000 bit/s
1 kB/s = 1000 byte/s
1 MBps = 1000000 byte/s
1 GBps = 1000000000 byte/s
1 TBps = 1000000000000 byte/s
"How much specific hardware speed I need to stream my media, from HDD to the tv?"
I thought I could share my thoughts with you and please, tell me if it was done before, I have not found any previous thread on this topic. I have no problem in being absolutely wrong in anything stated here, as long it leads to a usefull discussion. Sorry for typos or bad english.
Put that I don't have a 4k capable tv (and I won't in the near future), I'll use as reference a theoretical FullHD video (1920x1080, widescreen), at maximum AV bitrate encoding of 48 Mbps or 6 MBps [source].
What's the path the movie's bytes take from my NAS towards my HTPC box and how much bandwidth/tranfer rate I need from my hardware?
HDD ----> [motherboard interface ----> OS] ----> network interface ----> [HTPC box]
Let's examine each device separetely:
1) HDD
Model used here:
- Seagate ST4000DM000
- 4 TB disk space, 64mb cache
As a reference, the sequential read throughtput of this HDD on a Sata III interface is 138 ~146 MB/s [source]
(One Sata III port could be shared by 5 of this HDD model)
Possible ports (ascending speed order):
- USB 1.1 - 12 Mbps or 1.5 MBps
- USB 2.0 - 480 Mbps or 60 MBps
- Ultra DMA (ATA 133) - 1064 Mbps or 133 MBps
- SATA I - 1500 Mpbs or 150 MBps (Sata uses 8b/10b encoding [source])
- SATA II - 3000 Mbps or 300 MBps
- USB 3.0 - 5000 Mbps or 625 MBps
- SATA III - 6000 Mbps or 600 MBps
Hell, even Ultra DMA ATA 133's speed (1064 Mbps / 133 MBps) would be enough to transfer the 48 Mbps stream.
2) Network interface
Ethernet:
- Fast Ethernet (100BASE-TX) - 100 Mbps or 12.5 MBps
- Gigabit Ethernet (1000BASE-T) - 1 Gbps or 125 MBps
Wireless:
- 802.11b - 11Mbps
- 802.11a/g - 54Mbps or 6.75 MBps
- 802.11n - 600 Mbps or 75 MBps
- 802.11ac - maximum theoretical speed 6.8 Gbps or 850 MBps
Considering the theoretical HDD and network interfaces speed, a NAS device capable of streaming 1080p media could be built with the minimal requirements regarding HDD interface and networking:
- HDDs connected to USB 2.0, Ultra DMA ATA 133 or SATA I ports;
- Fast Ethernet (10/100) adapter or
- Wireless IEEE 802.11a/g (or 802.11n to leave some room for overhead and other traffic)
Conclusion:
Building NAS boxes with SATA III, SSD, Gigabit ethernet or IEEE 802.11ac wireless is a waste of hardware and money, regarding only the task of moving the media from the HDD to the network. It's not taken in consideration file copy/move/download operations.
NOTE:
xbps / 8 = xBps
1 byte (B) = 8 bit
1 kbps = 1000 bit/s
1 Mbps = 1000000 bit/s
1 Gbps = 1000000000 bit/s
1 kB/s = 1000 byte/s
1 MBps = 1000000 byte/s
1 GBps = 1000000000 byte/s
1 TBps = 1000000000000 byte/s