NAS Basics (Data Protection, Performance, Configuration and more)
NAS Basics (Data Protection, Performance, Configuration and more)PART 2
Other Features
NAS devices are not just boxes of storage on your network, many can provide extra funcitionality.
For example, the latest Synology Disk Station Manager (DSM) software (v2.2) gives the NAS the following features: (and ReadyNAS, QNAP etc provide very similar function sets)
RAID Management (RAID 0, 1 or 5)
iSCSI Target
Desktop Backup (PC/MAC Time Machine)
Server Backup
USBCopy
Windows Mac Linux Access
File Station 2
Encrypted FTP Server
Windows ADS Integration
Privilege Management
Web Station
Photo Station 3
Download Station 2
iTunes Server
DLNA Media Server
Printer Server
DDNS
Link Aggregation
Resource Monitor
3rd-Party Application Integration
Firewall
HDD Hibernation
Fan Control
Schedule Power On/Off
UPS
All of which are detailed here:
http://www.synology.com/us/products/features/index.php
Be sure to check the website of the vendor you are considering for a full feature set of the NAS you have in mind.
Power Consumption (go green with NAS)
A big advantage of having all your storage on a NAS rather than a server running 24/7 is the amount of power used.Below are figures for Synology boxes.I've chosen figures for a 1 disk box, 2 disk box and 4 disk box, with the information coming from their website.
Model, Spin, Access ,Idle, Hibernation
DS107e, 43w, 26.9w, 25.4w, 14w
DS207 , 52.2w, 32.7w, 28.3w, 11w
DS407, 68.5w, 50.6w, 47.5w, 13.4w
Updated 28/10/09 with newer Synology models.
DS109: 19w access, 9w hibernation
DS209: 25w access, 10w hibernation
DS409: 44w access, 16w hibernation
As you can see even when spinning and accessing the power consumption is way below that of a server.And when the idle parameter kicks in (time limit configurable on the Synologys), it can draw under 10 watts.Hows that against what a PC/server would draw?
So that's another great plus point for NAS.
Here is a calculation from NTM where he compares the Synology DS1010NAS to a PC.
ntm1275 said: So below is my attempt to explain the possible difference in running costs between a normal server and the DS1010
Any PC based business class server, will use well in excess of the 68 watts quoted by Synology, and may very well run into hundreds of watts
Using a mythical figure of say 200 watts for a PC based full server which is on 24/7, and comparing it to the 68 watts of the 1010on 24/7, I will show you an approximate difference in £'s per year between the two systems to your electricity bill if run 24/7
For comparison, I will use my own home kW charge of 14.11 pence, but yours may be higher or lower
PC Based Full Server
200 watts multiplied by 24 hours = 4800 watts
Convert 4800 watts to kW = 4.8kW
Multiply 4.8kW by 365 days = 1752kW per year
Multiply 1752kW by charge per kW = £247.20 per year
Synology DS1010
68 watts multiplied by 24 hours = 1632 watts
Convert 1632 watts to kW = 1.632kW
Multiply 1.632kW by 365 days = 595.68kW per year
Multiply 1595.68kW by charge per kW = £84.05 per year
I think the figures speak for themselves, £163.12 difference Click to expand...
Build your own NAS
Rather than looking for an off the self ready built NAS, there is nothing stopping you building your own.
One of the most popular methods of doing this is to use spare PC parts that you might have.
But you really need to watch the power usage when doing this.As shown in the "power consumption" section, running a normal PC 24x7 could really rack up the energy bills.
You'd be much better seeking out some of the newer low power CPU and motherboard combinations. (ITX motherboard boards, Atom CPU's etc).This should allow you to get much closer to the sub 50w ratings of even the largest standalone NAS devices.
Once you've built the hardware, you're going to need some software.
The main alternatives are:
1. Windows Home Server (license around £70)
http://www.microsoft.com/windows/products/winfamily/windowshomeserver/default.mspx
Or for those on a budget, there is always the free alternative.
2. FreeNAS
http://freenas.org/freenas
Filesystem
The majority of NAS boxes use the ext3 file-system (as they are in essence, mini-linux servers)
http://en.wikipedia.org/wiki/Ext3
Both Windows and Mac can read ext3 file-systems, so there is no need to format in NTFS, HFS or any other native file-system to make the NAS compatible with those operating systems.
Using 4k or 8k block sizes in ext3 allows a maximum single file-size of 2tb!!
Want a NAS? Ask yourself these questions
When considering buying a NAS, ask yourself these questions:
What is your budget? (including drives)
What usable capacity do you need?
Based on your capacity requirements, how many drive bays do you need?(max hard drive size at the moment is 2tb)
2 drives in RAID 1 give 2tb usable
4 drives in RAID 5 give 6tb usable.
What is your backup strategy? And have you budgeted for that?
Don't rely on RAID, consider an external drive plugged into the back of the NAS
What is your performance expectation?
Streaming Audio Video?Most of the basic models from the usual suspects will suffice
Heavy File Access and Multiple users?You might want to consider a higher spec unit.
What is you network infrastructure?
If wireless or 100mbit access only, then again, a low end box will probably suffice.
If you are expecting to get gigabit type performance, then you'll need to look higher-end. (and also get your network GigE end-to-end)
Once you've answered those questions, it should be easier to choose a model from each manufacturers range. (QNAP, Netgear, Synology the usual suspects)
Get on their sites and see if they provide all the features that you require.
Conclusion
If its "performance" you are after that is on par with your desktop, then forget it.That sort of NAS device just does not exist in the consumer market place and price point.A NAS is no desktop hard disk replacement.
I'd suggest you continue to use your desktop to do all your intensive work requiring high speed access (uncompressing large files, video editing, video rendering and encoding etc) and use the NAS for protected storage, backups, video/audio streaming or any other low speed access.
Decide what you want from your NAS, be that fault tolerance levels and extra features as listed above.Then use the myriad of webpages dedicated to hardware reviews to make your mind up and of course the forums here at www.avforums.com
Other useful sites:
www.smallnetbuilder.com
www.tomshardware.co.uk
Both of which have their own forums too.
I hope this mini-guide has helped you.If you have any questions, comments or corrections, then please let me know.
One more thing, if you post a question up and someone goes to the trouble of answering you, please have the courtesy to use the "thanks" button to show your appreciation.Rudeness is not a welcome attribute on these forums. NAS Basics (Data Protection, Performance, Configuration and more)
PART 1
Overview
Back in 2007, I put this little guide together after spending a good few weeks researching a NAS purchase myself.I have picked up much of the information from other forum members posts, so many thanks to them for their help, also lots of different websites and reviews of NAS devices.I want this post to be organic and grow or change as appropriate.So if you have any comments about any of the content, want to add anything, change anything or see any glaring errors, please let me know and i'll update accordingly.
Finally, i hope you find this post useful and that it will save you time digging around finding it out for yourself.I wish there was something like this before i started looking!!data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
NAS/DAS Basics
NAS Stands for Network Attached Storage, this is not to be confused with DAS, which is Direct Attached Storage asthere are key differences.
First question, do you need a DAS or a NAS?Easy to answer.
Got 1 PC and want more storage directly attached or the ability to take backups? - DAS
Got 1 PC, want more storage/backups plus you've got a home network and see your infastructure growing? - NAS
Got more than 1 PC/device networked and you want devices on your network to see extra storage or a backup method? - NAS
DAS is a storage device that normally connects to either the USB or Firewire port of your PC and it is mainly used by that PC.Yes, the storageon there could be "shared" at the operating system level, but the PC that the device is connected to would have to be switched on whenever the storage is to be accessed by other devices on your network.DAS boxes are also very useful for taking backups to from the attached PC.
NAS devices on the other hand plug directly into your network router or switch allowing all PC's and devices on your network to access the storage at the same time.
NAS Devices are basically a "box of logic" with space for hard disk(s) inside.The number of hard disks depends on your requirements.There are 3 main disk configurations.The logic part providing whatever features your NAS box has, including various levels of data protection.
NAS Configuration Types
There are 3 main configuration types of NAS box, here's a short explanation of them:
1 disk boxes
This the entry level of NAS, but not a recommended method for storing important data.The reason is that you have no resilience or protection from a hard disk failure.If your single hard disk fails, then you lose all the information stored on your NAS.Probably best used for backup purposes only or where data protection is NOT REQUIRED.
2 disk boxes
A much better entry point into NAS.Now you have the ability to protect your data by using mirroring.This is where the logic of the NAS box comes in as the hardware handles the resilience.If you use RAID 1, also known as mirroring, you have 2 drives in the NAS, but one disk is an exact and instantly updated copy of the other so that in the event of a single hard disk failure your data is not lost.You would then replace the faulty hard disk with a new one, the NAS would recreate the copy for you and away you go again.
The downside of RAID 1 is a 50% loss of usable storage as you can only use one of your 2 drives for data, with theother one your protection.
You can also configure these 2 disk boxes as single disks or stripe the data using RAID 0, but there is no protection for your data doing this and it is not recommended if you want to safeguard your data.
4 disk boxes
These devices offer more protection and can also provide better performance. As with the 2 disk boxes you can use RAID 1protection on the pairs of disks and even RAID 0 (but why would you want pure striping with no protection?).
The major advantage of a 4 disk box is the ability to use RAID 5 which is data striping with parity.(requires a minimum of 3 disks)This means that for performance the data is spread across all drives used, but also, so is your protection (the parity).So in the event of a single disk failure you replace the faulty disk and the contents are rebuilt using the parity data from the other drives.
The only downside to this is the loss of usable storage from 1 of the drives in your configuration.But an acceptable loss to get a good level of protection for your data.
** NOTE ** Protecting your data using RAID is no substitute for a proper backup regime.
Most new NAS drives allow you to connect an external drive to them to schedule backups.You can connect these via USB or sometimes eSATA.
Another option is one of the internet/cloud backups available.
Remember with all RAID configurations that ideally you want exactly the same drives, doesn't have to be the same makes etc, but it helps, but definitely the same size otherwise the RAID array will only be created to the lowest sized disk.So if you've got 1 x 200gb and 3 x 300gb disks for example, you would only be able to create a raid 5 array using 200gb per disk.
For a full description of how the various RAID options work, look here:
http://www.acnc.com/04_01_00.html
http://en.wikipedia.org/wiki/Standard_RAID_levels
Performance
In the main, NAS boxes don't perform as well as single hard disks - FACT.
This was a harsh lesson for me as i was expecting blinding performance from NAS boxes, you just don't get it.
Back in 2007, a single Samsung Spinpoint T166 HD321KJ 320gb drive had an average read speed of 63.20 MByte/Sec (update: in 2010, newer drives around the 90MByte/Sec mark)
Back in 2007, most sub £1000 NAS devices ran somewhere between 10 MByte/Sec and 40MB/Sec, with between 15-20 MByte/sec the average. (update: medium range NAS can now post figures around 50MByte/sec, whereas higher end units are now pushing 70-100MByte/sec
This link to Smallnetbuilder shows typical read figures for many popular NAS devices when connected to a GIGABIT infrastructure.
http://www.smallnetbuilder.com/component/option,com_nas/Itemid,190/chart,13/
Remember, these figures are for the NAS devices connected to Gibabit ethernet.To get these figures, all elements of the chain need to be gigabit ethernet.So if you are copying a file from your NAS to your PC, the NAS connection, the network switch and the PC ethernet card all need to be working at gigabit.If any part of the link runs slowly, all the other parts will be dragged down to the poor performance levels of that single part.
So if we show you this chart, with is the average read figures of the same NAS devices but when connected to 100MBit networks you can see that none of the devices can get more than 10MB/Sec because the 100MBit network connection is holding the device back.Very Important!!!
http://www.smallnetbuilder.com/component/option,com_nas/Itemid,190/chart,11/
So if you want to get the best out of your NAS and the devices that you want high performance from, ensure that all these elements are all running through a gigbait switch and use gigabit ethernet cards and appropriately capable cabling (Cat 5e or Cat 6)
Also, read access is normally better than write access.
Another point worth making is that even if you have a NAS capable of 100MByte/Sec with full Gigabit networking all along the chain, it still WONT perform as quickly as a single 100MByte/Sec hard disk in your PC.This is because networking (switches/cabling/protocols) add latency to each read and write.
So if you know you only have 100Mbit network or will only be accessing the files over your wireless network, you've got to think is there any worth in spending lots of money on the fastest box out there when the rest of your infrastructure is incapable of using all that bandwidth?
Wireless Device to Gigbabit switch - always 6.75Mbyte max (wireless max drops it down)
100Mbit ethernet to Gigabit switch - always 12.5Mbyte max (100Mbit max drops it down)
gigabit switch to gigabit switch - always 125Mbyte max (full speed allowed all the way through)
So unless you connect both source and destination devices at gigabit,(ie PC and NAS) you are never going to get the best transfer rates out of any NAS. Wireless and 100Mbit connections just strangle the throughput down to the lowest common denominator.
For example, in this chain, your speed will only be as quick as the 'slowest' element.
NAS Hard Disks > NAS Device Capability > NAS Network Card > Switches/Routers > Host Network Card > Host OS > Host Hard Disks.
So if you have a laptop as your host and the hard drive is a small 5400rpm disk that is only capable of 30 Mbyte/Sec, then that's what you'll be limited to, regardless of how good the rest of your kit is.
Another performance issue that has come to light (thanks again ntm1275), this one is round PCI bus limits.
The quote below is from AMD
"The typical PCI bus has a maximum theoretical bandwidth of 133Mbytes and is split between all devices using the bus. In an era of Gigabit Ethernet and RAID controllers, 133Mbytes will act as a bottleneck whether or not PCI uses a shared bus topology"
It basically means that all the PCI slots use 133Mbytes/s, so if you have 5 PCI slots, that would be 133divided by 4 equals 33 each.
I can vouch for this as I had a Gigabit ethernet card in a PCI slot and it was capped at around 30MB/Sec.
A PCI express (PCIe) can run at 250MB/s simultaneously in and out and is not shared with other PCIe slots, so theoretically a PCIe x16 (graphics card slot) could reach 4GB/s
http://en.wikipedia.org/wiki/PCI_Express
So if you can find a PCIe network card, it should give a speed increase over PCI models.
Media Streaming
One of the main reasons we are all looking at these NAS devices is streaming media to various devices (HTPCs, XBOX 360s, PS3, squeezeboxes and media streamers etc)
I've done some calculations using figures found on videohelp.com and come up with the following. These are the"maximum" data rates of video for the following formats:
1x CD-ROM Media: (150 KBytes/sec) 0.15 Mbytes/Sec
And obviously, mp3 and other compressed music formats are less demanding than standard cd-rom material.
Max SD-DVD Media: 1.225 Mbytes/Sec
Max HD-DVD Media: 3.67 Mbyte/Sec
Max Blu-Ray Media: 5.00 Mbyte/Sec
Average bitrate 720p mkv: 8000 kb/sec (1.00 MBytes/Sec)
Average bitrate 1080p mkv: 12000 kb/sec (1.50 MBytes/Sec)
This is a great page for data-rate conversion: http://web.forret.com/tools/bandwidth.asp
EDIT: Please feel free to correct me on any of these figures if you think they are wrong.
I must stress that these figures are theoretical MAXIMUM figures for each technology and the normal usage from these formats would be lower.Plus any ripped files/clips are usually re-encodes with substantially lower bit-rates too.
So as you can see, in theory you should be able to stream even 5.00 Mbyte/sec blueray across a 100MBit Ethernet on the majority of the NAS boxes on the smallnetbuilder list.
The problem will come where you want to stream high volumes to multiple devices.Maybe the kids are watching something on one machine from the NAS and you are in the living room watching another media stream.That's when you need to think is the NAS I'm thinking about going to fulfil my requirement now and for the near future? and is my networking upto the job?
Obviously, wireless networking brings all sorts of other parameters into question with both lower and less than consistent connection speeds.
This table shows the Theoretical Megabit per second speeds converted to MegaBytes per second of various connections (thanks for ntm1275 for posting this).It gives a good overview of the various technologies and achievable speeds.
Code: Megabit first figure (Mbit)MegaByte second figure (MB)USB, Low speed (1.0), 1.5 Mbit/s, 0.18 MB/s USB, Full speed (1.1), 12 Mbit/s, 1.5 MB/s USB, Hi speed (2.0), 480 Mbit/s, 60 MB/s Firewire 400 (IEEE 1394),400 Mbit/s, 50 MB/s Firewire 800 (IEEE 1394b), 800 Mbit/s, 100 MB/s CD-ROM, 1x, 1.2 Mbit/s, 0.15 MB/s CD-ROM, 52x, 62.4 Mbit/s,7.8 MB/s DVD-ROM, 1x, 11.1 Mbit/s,1.3 MB/s DVD-ROM, 16x, 177.3 Mbit/s, 21.1 MB/s Blu-Ray ROM, 1x, 54.0 Mbit/s,6.75 MB/s SATA I, 1200 Mbit/s,150 MB/s SATA II, 2400 Mbit/s,300 MB/s54g wireless, 54 Mbit/s, 6.75 MB/s108n wireless, 108 Mbits/s 13.5 MB/s10Mbit LAN, 10 Mbit/s, 1.25 MB/s100Mbit LAN, 100 Mbit/s, 12.5 MB/s1000Mbit LAN, 1000 Mbit/s,125 MB/s
Listed here on Wikipedia is a far more exhaustive list of equipment, standards and speeds: http://en.wikipedia.org/wiki/List_of_device_bandwidths
The above speeds are only theoretical speeds that the devices "should" be able to reach, however many struggle to reach these speeds.
Part 2 of this Sticky continues in the next post. Very useful thank you. data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 Nice guide now a sticky for your efforts data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 Added section relating to Power Consumption. data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7 I've ordered a PCIe network card (should arrive Monday), so I'll post some transfer figures from PCI and PCIe
I'm hoping the PCIe card will increase speeds
Also, apparently there is a difference in using XP or Vista
On a previous test I ran (my PC has dual boot), XP transfers files a lot faster than Vista
Vista apparently uses more network resources than XP, but I read somewhere that Microsoft has issued a patch that has help Vista somewhat, but XP is still faster
I've also tried using a FTP client, which does appear to be faster still
So I'll do various tests transfering files with XP, Vista, PCI, PCIe and FTP, and also some using wireless to and from my NAS and from PC to PC etc etc, sometime this week if I get a chance I've compiled some information using an Onboard vs PCI, and XP vs Vista, and I've also thrown in the use of an FTP client, some results are very interesting
http://www.ntm1275.f2s.com/nas_transfer_rates/index.htm
When I have received my new PCIe card I'll update the information I've done my testing to find out which combination of various common network cards, operating systems and software work best for maximum file transfer speeds when reading and writing to my own Synology NAS devices
Now that I have finished, I can share my findings with everyone
The figures below are not exhaustive, and only apply to my own system, but can be used as a baseline guide to your own system's performance
Test Rig
ECS nForce 4 A-939 Motherboard
AMD Athlon64 4800X2 Socket 939 CPU
Elixir 2GB DDR400 (4 x 512MB) RAM
Inno3D GeForce 7900GS 256MB Ram Graphics Card
Wester Digital 74Gb Raptor Hard Drive
Network Cards
nForce 4 onboard Gigabit (uses PCI bus)
Belkin F5D5005 v2000 PCI Gigabit
Intel Pro/1000 PCIe Gigabit
Network Switches
Netgear 8 port GS608
Netgear 5 port GS605
Operating Systems
Windows XP Professional SP2
Windows Vista Business
Software
CuteFTP 8 Professional
Synology Products
DS-106e (266mhx CPU, 32MB Ram) 1 X Seagate Barracuda 7200.10 SATA II 320Gb Hard Drive
DS-207(500mhx CPU, 128MB Ram) 2 X Western Digital Caviar SE16 750Gb Hard Drives
All test were carried out three times, and an average was taken of the three runs
All test were done using a 1.06Gb mkv video file
Jumbo Frames have been enabled (9000)
The test with the FTP program is only shown using the PCIe network card because during the test all the different cards had the same transfer rates and to include them would have made the graphs more confusing
All figures are in Megabytes/second
/proxy.php?image=http://www.ntm1275.f2s.com/synologygraphs/ds-106e.jpg&hash=238f2b573c8296785a6c28a90da32074
/proxy.php?image=http://www.ntm1275.f2s.com/synologygraphs/ds-207+.jpg&hash=7228f981b5ab3e4319ba07ea3283ac82
Concluions
1. There is a slight advantage by using a PCIe network card
2. XP is faster than Vista for Reading, but falls well behind Vista for Writing. There must be someting in XP that limits the Write speed as all figures seem to be topping out at about 10.53MB/s
3. The 207is well ahead of the 106e in Reading and Writing as expected due to the faster CPU and more RAM
4. Using an FTP program to transfer files from the NAS is by far and away the fastest option, FTP best 54.25 and 33.90 MB/s, Windows XP best 26.46 and 20.47 MB/s
5. An FTP program is also the fastest for Wrting to the 207but not for the 106e, where a combination of a PCIe network card and Vista is fastest
Summary
Best case scenario for DS-207= FTP Program and Vista
Best case scenario for DS-106e = FTP Program and Vista
Final Thoughts
Has XP got a bit of a bug when Writing to both the 207and 106e, or is there something that needs to be changed from the standard XP configuration that would bring it's speed up
If anyone has any ideas, I would like to hear from them
The value of the faster CPU and more RAM of the 207is evident over the 106e
The difference in the price between the two, is well worth the paying
I am so glad I bought my 207
My 106e has done me proud for the past year, but the 207is something else Wonderful analysis NTM.The PCIe card really does the business for 'FTP reading' by the looks of things.Now how do we incorporate FTP access into all our apps?? data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7
Have you posted your findings on the Synology forum?I'm sure people on there would be very interested too and someone might have the answer to the XP problem.I know i'd be interested in what that is.
I'd assume that my 407 would have similar performance to your 207 as they are built around the same 500mhz proc and 128mb ram combination.Which is good to know.
Thanks again. Yes I have posted it on the Synology forums
The method used was to copy and paste the file while I timed it with a stop watch - more realistic than synthetic benchmarks
I was expecting more from the PCIe card to be honest, perhaps if it was in a more modern PC than mine, it may be a different story
The Belkin card had an anoying habit of reverting to 100mb after coming out of standby, and I would have to remove the card from the case and then reinstall it again
Yes I would asume that your 407 should have similar performance, depending on the spec of your PC
The FTP transfer rates blow Windows out of the water, I have tried to search for information about optimal network configuration for Windows, but I haven't found any as yet
The only thing I can think of is that Windows does not like the Linux file system on NAS devices, where as FTP bypasses Windows