A few misconceptions....

[StorageJoe]

I'm a long time reader but first time poster to this forum. It seems like there are some rampant misconceptions that I would like to address.

First is to clear up confusion surrounding SATA II:
SATA II is the name of the organization which authored many extended specifications including NCQ, Hot Plug, Staggered Spin Up, 3Gbits/sec, Port Multiplier and Port Selector. All these specifications will be combined into one spec and SATA II will be completely gone from our lingo. None of the drives available on the market today labeled as "SATA II" meet all of these criteria. The new spec and replacement for SATA150 will be SATA3gb. Currently, SATAII is a marketing term.

SATA II ≠ 3Gbits/sec
3Gbits/sec is simply a speed enhancement from current 1.5Gbits/sec(external transfer rate)

3Gbits/sec SATA will not be twice as fast:
Most 3Gbits/sec performance will only be seen in multi-drive systems…internal transfer rates are still below 100Mbytes/sec.


The second point I would like to address is NAS storage. NAS storage (network attached storage) is not a substitute for SAN. There is no such thing as an iSCSI SAN. I see many posts of people wishing to build a "storage server" for their homes by placing an inexpensive computer in a closet and running a file server. Most people use 10/100 in their homes, but even if you upgraded to gigabit cards and a gigabit switch, a NAS solution is still dreadfully slow. Gigabit ethernet is 1000 megabits/sec or 125 megabytes/s. Realworld you can get a sustained transfer rate of about 50megabytes/sec considering that you allow this transfer to suck down all of your network bandwidth. This gives you a transfer rate roughly half that of the internal transfer rate of your drives. If you're running 10/100, you're getting about 5MB/sec real world. While it's fine for archival storage there is no sense in trying to use it as nearline storage. One would be better off buying a previous generation tape drive than trying to build a nas box.

 

[westrock2000]

I transferred 40gb worth of data a couple times from the Mini to a very good PC with Asus mobo gigabit, 3.0 P4, and SATA. The Mini was actually reading from the external USB, but I only sustained about 9mb/sec. This was on a local LAN with about 30' worth of cable on the same router. Technically none of the formats involved should have limited me to that.

 

[StorageJoe]

You may have had a gigabit nic, but was it a gigabit router? Max theoretical on a 10/100 is 12.5 MB/s , so 9 is reasonable. If everything was in fact Gigabit, 9 is also plausable due to the amount of overhead involved in tcp/ip as well as any other traffic on your network that may have been sucking down bandwidth. Your bottle neck is the fact that you were going over a network. Hence my point that NAS is no replacement for SAN or DAS.

 

[westrock2000]

The router was a Linksys WCG200 which is a 10/100, and the Mini which has a 10/100 as well. I would only consider an NAS as a convience, so that a whole computer doesn't have to be on all the time to share something like music or other media. If you want to run a game or something off of it....I don't know

 

[StorageJoe]

9mb/s over 10/100 is pretty good. Like I said before though your bottleneck is in fact the network. Instead of having a NAS box it would make more sense to just add another HDD to each PC. You'd spend way less money and it'd be 10 times faster.

 

[DougLite]

First, welcome to the [H] forums, and to Disk Storage. Here you will have a chance to answer many storage questions...and have some answered yourself. After doing a quick little search, I see that all of your posts so far have been here in Disk Storage. Don't be afraid to venture to the other forums

I'm guessing that many of your statements about SATA feature identification and nomenclature are based on this document published by the SATA International Organization. It is not uncommon for vendors to 'hi-jack' standards and use them, or parts of them, to their marketing advantage. Part of the business, as a higher interface speed is an easy selling point to the average consumer. As we all know, selling points can be quite misleading, particularly in the case of hard drive interface speeds. The buffer to/from disk rates are much more significant, but even that rate has limits as a measure of hard drive performance.

I am quite sure that no storage subsystem is 100% "SATA-II" compatible. The linked document refers to port multipliers and port selectors, which although I have seen technical data on them before and referred to them as an up and coming technology, we still aren't there yet with any shipping SATA hosts. Many SATA hosts and drives support 3 gbps transfer, NCQ, and hot plug, which are the features of most interest to consumers at present, so those are the ones that get implemented. It's a chicken and egg problem - without demand for the features, who would think to incorporate them into the standards? and without the standards, how would you hope to bring the features to the consumers that demand them?

Also, I would like to address your concerns with NAS. Many users find it extremely practical, and I myself wish I had one. I have a very large music collection that I would like to be able to play at any of three locations in my house. At present, with your suggested method of a hard drive hosting it locally at each location, I must have a "master" collection where all of the updates and additions are performed, then push those updates and additions to the other copies. If I had a NAS setup, I could simply access one set, and make changes at one location and have it instantly updated on all of my systems. Even allowing for fault tolerance in the NAS, I only have to buy two big drives to host the content, and small boot drives for my clients, rather than having a big drive in all of my playback stations. NAS is great from a practicality standpoint for situations like this where throughput is not a priority. Your comments on throughput are well taken, and where speed is a concern, NAS falters. However, most NAS users, especially on this board, find it extremely useful and economical, and as WestRock points out, don't need killer throughput.

And that leads me to another reminder. While there are some IT Pros on this forum, it is primarily a gamer and home computer enthusiast community. Many things that are true in enterprise computing must be evaluated from a different perspective, and may not be true at all, here. I cannot tell you what to do, but I suggest keeping that it mind, as it does much to explain the views of other members, and will help you as well. Also, read up before you tackle "misconceptions" on my "pet topic," RAID-0

 

[Wolfsbane2k]

Welcome to the forums StorageJoe...

I'm in total agreement with Douglite on this one.

Although i have always looked at NAS as a suitable storage solution for the typical home user that has a lot of storage that wants to spread music and video across a couple of machines - a pc in a bedroom, pc in office, mini-pc/xbox in the living room connected to the hi-fi & tv etc.

Let alone somewhere to keep all the windows updates to spread across all the machines on the home network... although it's slow, its more efficent to keep one hard disk with the patches etc on rather than download it from the internet at 1Mbit download compared to a standard 9MByte network transfer....

It's a matter of as cheap as possible for as efficient as possible.

And I agree - SAN would be brilliant, but would you ever recommend it for a company of 4 people just doing office work? Or would you tell them to get a dell server and stick hard drives in it.

 

[StorageJoe]

Well by definition a SAN needs at least 3 servers w/ firbe HBAs and a fibre switch, so no I wouldn't tell a company of 4 to go get a SAN. I can see the appeal of such a system, but I feel most people don't realise that it's slow and kills your network bandwidth. If you're streaming music, great. If you're looking for distributed storage, get an external USB drive, it's faster and doesn't hog your network.

 

[StorageJoe]

I'm not trying to start a flame war or anything, but sharing music from a PC and adding a dedicated NAS box are two completely different things.

 

[Wolfsbane2k]

I'm not trying to start a flame war or anything, but sharing music from a PC and adding a dedicated NAS box are two completely different things.

Oh, don't worry, flames only ever come from my psu as it takes out my harddisks...

Althought i understand where your coming from wrt to sharing music and a NAS being different, different requirements for databandwith, access speeds etc, i'm not sure i agree about the external usb box being the best use for a home user with a few pc's.

Although the general talk here is defined as NAS, many people want to turn it into more than that - look at the uNSLUng hacks for the linksys NSLU2 boxes. I personally use a NAS for more than NAS purposes - it's also an email server, web server, web development box opengl rendering center. Difficult to get all that running on an external enclosure. It's definately a low powered server

And it cost me £40 more than firewire enclosure - because everything in it is hand-me-downs from my old system builds - i just added 1gb more ram, and i can add 4 hd's into it.

I guess it's a Pro/Con & Compromise Match:

External Hard Disk
Pros:                           Cons:
Access Speed             Limited File Access Control ( between machines)
Transportability         Difficult for multiple machine access.
Small Size               System Functions Not upgradeable (Storage Only)
Cost                     Limited System Storage

NAS/Server
Pros                             Cons
Versatility              Always On Power Consumption
Storage Expandability    Limited Transportability
Multiple User Access     Costs More.
RAID 5 in 1 box          Harder to Configure ( pos!)
File Access Control

Ok - so removing the extra functionatity of a server ( email access etc) , you end up with an ideal of of 1xNAS (250gb) for music and a 40 gig external drive for moving large files around? That 40Gb external will cost the same initial cost as an old knock togther...

Not a bad idea, but i'm a lazy bugger and prefer sitting in front of one pc, playing games, while the pc is downloading from the server rather than getting up out of my chair and running to my other PC for the harddrive!
To be honest with you - that's not a bad idea for all the Windows updates @ 600 meg from retail release now - including sp1, sp2, and office 2003 sp1!