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ReadyNAS Performance Expectations
By dbott | May 15, 2010
So, you’ve got your new ReadyNAS device and are wondering why it’s not screaming at gigabit speeds. Before going to much further, let’s be sure that our equipment is capable of delivering the speeds we’re looking for.
The Slowest Network Link
One of the problems is that many people fail to take into account that network performance is limited to the speed of the slowest link. Even though the ReadyNAS has a gigabit interface, if your router or network switch does not support gigabit, you will only get speeds that match the network device (typically 100 Mbps for most devices).
You also need to consider the speed on the network card on the PC. If the NIC on the PC is not gigabit or you’re using a wireless connection, performance will also be reduced.
In order to achieve maximum performance, all device connections would need to be wired gigabit connections. This requires:
- gigabit ethernet cards in each computer
- a gigabit-capable router or switch
- category 5e or 6 ethernet cable
- optional jumbo frame support
If you’re looking to upgrade any of your network equipment, be sure to check the Hardware Compatibility List to make sure that the equipment is supported by the ReadyNAS.
Bits-per-second vs. Bytes-per-second
Network throughput is generally measured in bits-per-second (i.e. 100 Mbps, 54 Mbps, etc.) and disk I/O is typically measured in bytes-per-second (i.e. MB/s). When measuring performance, pay close attention to the big B (as in Bytes) vs. the little b (as in bits). A hard-wired connection of 100 Mbps is theoretically capable of 12.5 MB/s (12.5 MB/s x 8 bits-per-byte = 100 Mbps), however, network overhead typically reduces it to about 80% (9 MB/s on average). Same for wireless 802.11g, however, the overhead is much greater and results in about 22 Mbps max (or approximately 3 MB/s).
The only way to maximize performance is to make all links wired gigabit, which should increase disk I/O to it’s maximum.
Typical Performance Expectations
There are a number of factors that can affect performance, such as the size, type and number of files, as well as the protocol used (CIFS, NFS, AFP, FTP, HTTP, etc.). Under ideal conditions, a typical user should be able to achieve the following performance:
- Wireless 802.11g: 2-3 MB/s average (Vista / Windows 7 users should read this)
- Wireless 802.11n: up to 6 or 7 MB/s average
- Fast ethernet (wired 100 Mbps): Max 12.5 MB/s – average 9-10 MB/s
- Gigabit ethernet (wired 1000 Mbps):
- 10 GbE (wired 10,000 MB/s):
- ReadyNAS 4200: 852 MB/s (using 802.3 ad Teaming, drag & drop 20 GB file over CIFS)
ReadyNAS Device Limitations
Performance is also limited by the CPU in the ReadyNAS device itself. The ReadyNAS devices that use the sparc-based IT3107 CPU are limited to a maximum speed of about 25-40 MB/s, where as the Intel-based models like the Pro can surpass 100 MB/s. There are also a number of tweaks that you can make in order to optimize performance on the NAS. Be sure to read the article on optimizing performance: http://www.readynas.com/?p=310
Desktop PC Limitations
Another limitation people fail to take into consideration is the performance of the desktop client computer that they’re using. The disk I/O of most desktop-class PCs are limited to about 60 MB/s and would never be able to reach the capabilities of a product like the ReadyNAS Pro, unless your PC was configured for some sort of RAID. Some might wonder what the benefit of owning a ReadyNAS Pro is if you will never be able to max out the performance. A single PC might not be able to max out the Pro, however, if you have multiple gigabit clients simultaneously reading and writing to the Pro, it will be able to keep up. Using 802.3ad LAG, the ReadyNAS Pro has achieved 240 MB/s read speeds and 140 MB/s write speeds when being accessed with multiple Macs.
Next Steps
Okay, so you’ve checked everything and you’re still not getting the performance you expect. What should you try next?
- Check for network errors in Frontview > Network > Interfaces > Show Errors.
- Direct-connection between PC and NAS. This will eliminate any incompatible network equipment.
- Replace ethernet cables with new or known-working CAT 5e cables. A flaky cable on the NAS or PC can cause all sorts of grief.
- Disable or uninstall any security software. Some security software can be overly agressive.
- Try a different protocol. If using CIFS/SMB (Windows), try copying files using FTP to see if the performance is comparable.
- Try a different computer. If possible, try using a different computer to eliminate the PC as the source of the trouble.
- Try a different operating system. If your PC has multiple OSes (or you have a Live Linux CD), try booting into another OS.
- Check hard disks. Flaky hard disks can cause intermittent read/write issues that can slow the NAS to a crawl.
- Check your RAM memory. If you have upgraded your memory, you may want to re-install the original memory to eliminate the RAM as the culprit.
- Factory Default. Sometimes the OS on the NAS becomes corrupt and can be corrected by resetting the unit. Be sure to backup any data on the unit.
- Contact support. If you’ve exhausted all of the above, you should download your log files and contact support.
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