Mac Discussion

I've posted half a dozen different ways at MacRumors searching for much needed help for a storage crisis I'm having right now. I have a MBP (no, not MacPro) because I need portability when in the field but my storage is for editing at home. I don't want to give anymore info just yet because it always seems to take the responses off track. For now I need to know this:

The MBP has one expresscard slot. So if you use an eSata adapter (even if it has dual eSATA ports) it would only have one eSATA channel..... And that would be limited by the express card slot and further still by the type of card (make, model, etc..).

My question is: with Barefeats claiming even the best eSATA card for a MBP being 200MB/s, using a dual eSATA RAID connection for a stripped array would be limited to 100MB/s per port.

Is this correct? Because I'm trying to understand this to see if it's worth building a RAID setup for my MBP when I'm home. Would a RAID0 setup where I'm limited to 100MB/s for each port on a single eSATA channel see any benefit over a single eSATA HDD. For some reason no one answers this specific and fundamentally critical question of mine.

I am not interested in FW800 because I want the fastest I can get.

So you are talking two external drive cases, each with 2 drives setup as a RAID 0, and then each one going into each port on the eSATA card, right?

---------------------------------
Posting And You: [www.albinoblacksheep.com]

It looks like the Tempo SATA Pro ExpressCard might be the fastest. I think you only get continuous throughput of over 100 MB/s with new large drives when they are under 1/3rd full. You would need two hard drives on each channel to really be sure that the ExpressCard is close to being fully utilized if the drives are starting to fill up.

It might be possible to get close to saturating an ExpressCard with a single SSD. What is the smallest drive capacity you could work with?


From a Raines Cohen T-Shirt: "The day Microsoft makes a product that
does not suck will be the day they start making vacuum cleaners."

rawdawg Wrote:
-------------------------------------------------------
> I am not interested in FW800 because I want the
> fastest I can get.

Then you're interested in FireWire 800 because there's no performance advantage to eSATA in single channel setups:

[www.barefeats.com]

-----------------------
Nemo me impune lacessit

Sonnet is pretty reputable. (See below...) While the drivers are reliable under 10.4-10.5, Sonnet hasn't updated their drivers for Snow Leopard yet. The drivers may work under Snow Leopard, but they're known to cause crashes and hangups.

Check with the manufacturer of any card you're considering and make sure that their drivers are certified to work with the OS that you're running.

Dunno if this'll help. It's old:
[macperformanceguide.com]

Quote:

Conclusions

The Sonnet Tempo SATA Pro ExpressCard/34 with its Marvell chipset is the speed champ as of December 2008: speeds are substantially higher than with my former favorite, the FirmTek SeriTek/2SM2-E.

Please note that the high performance seen here requires Sonnet’s more expensive “Pro” card, not the regular version (which like the FirmTek offering is based on the Silicon Image chipset and likely to experience the same issues and performance).

When choosing eSATA on the MacBook Pro for performance reasons, the higher price of the Tempo SATA Pro ExpressCard/34 is easily justified for big jobs, such as Photoshop. And for backups of large data sets, the higher sustained throughput will cut the time down considerably.
System software version, firmware version and MacBook Pro variant have a large influence on performance, please review the test parameters carefully.

Since you visit the barefeats site, you did see the 4 bay OWC case they tested?

Limited, but they still got 200 MB/s with it.

You could get 8TB on a single eSATA port.

---------------------------------
Posting And You: [www.albinoblacksheep.com]

chine Wrote:
-------------------------------------------------------
> rawdawg Wrote:
> --------------------------------------------------
> -----
> > I am not interested in FW800 because I want
> > the fastest I can get.
>
> Then you're interested in FireWire 800 because
> there's no performance advantage to eSATA in
> single channel setups:
>

You are kidding, right? A 4 year old test that includes G4 hardware... am I going to have to point at you and laugh?



From a Raines Cohen T-Shirt: "The day Microsoft makes a product that
does not suck will be the day they start making vacuum cleaners."

chine Wrote:
-------------------------------------------------------
> rawdawg Wrote:
> --------------------------------------------------
> -----
> > I am not interested in FW800 because I want
> the
> > fastest I can get.
>
> Then you're interested in FireWire 800 because
> there's no performance advantage to eSATA in
> single channel setups:
>

I actually did see that test and it's directly related to my question. I want to know if a dual eSATA card means it still shares the same data channel (as I suspect it does). Because it also states in the test that eSATA 2x2 is faster than FW800.

Thanks for the advice on cards. I've clearly seen eSATA is faster than FW800, that I'm not sure is worth arguing. The unresolved question is how to utilize eSATA to it's potential. Especially when it comes to RAID. A single SSD is an excellent suggestion for the quick solution but I need 2TB storage and don't have money for SSD. So I feel HDD RAID0 would be best. I just don't know the figures to determine if stripping is really worth it since I still have the single eSATA data channel.

After that is resolved, I want a backup. But I don't require realtime redundancy and to save money was thinking against mirroring or RAID 0+1. Instead I could use a separate backup drive to do daily backups. I feel this would insure my mirrored drives wouldn't slow down the array. RAID 5 would be even better since I get more storage for the same amount of drives, but I haven't found any information on how to make this possible cheaply.

Thanks a ton everyone for all your help. This is exactly what I'm going through right now. For some reason the people at MacRumors keep avoiding the specifics of these questions. I can't spell it out any more exactly. This is what I need to know.

Thank again!

Also... in addition to my last post above which pleeeeas pleeeeease pleeeease read first since it's the main concern here I just was reading about the possibility of getting an expresscard FW800 adapter.. Then I would effectively have 2 FW800 channels, correct? Therefore I could definitely go 2x2 or 4x2 the FW800 route.

I am VERY surprised these issues haven't come up before......

If a dual channel eSATA ExpressCard can only reach 200 MB/s, then that is likely the limitation of the bus connection between the ExpressCard and the Northbridge.

I glanced at the threads at MacRumors. RAID 0 is faster than RAID 1 because with RAID 0 the data is being split between two drives. With RAID 1 (mirroring), all the data is going to both drives. RAID 5 with three drives is likely to be slower than RAID 0 with two drives because there is some overhead in striping the parity blocks.

You could have a single 2 TB drive as a backup of two 1 TB drives set up in a RAID 0 array.


From a Raines Cohen T-Shirt: "The day Microsoft makes a product that
does not suck will be the day they start making vacuum cleaners."

Mr. Penguin, thank you so much for coming to the rescue (as you always do the many years I've been posting here).

I see you read that particular thread, thank you. You explanation makes sense and confirms my setup could work. I actually started other threads over there specifically about this eSATA bottleneck at the expresscard which is what my current line of questioning entails. Could I simply as this of you:

Would I benefit from a RAID 0 array using eSATA on my MBP if the single data channel can only reach 200MB/s? I'm thinking it would have to hooked up to a dual port eSATA adapter and with a dual eSATA enclosure such as this [eshop.macsales.com] or this [www.newegg.com] but then again the dual port eSATA would be negated because it's all funneled through the same data channel -- but of course there are no dual enclosures that have a single eSATA connection unless it has a RAID controller.

So the alternative to get the real throughput needed to benefit from RAID would be to get an ExpressCard to FW800 adapter and then you have 2 FW800 data channels and can effectively RAID 2 FW800 drives..... Am I missing something.

I suspect I must be confusing people with my line of questioning because it seems simple to me and yet no one can answer this. And the fact I haven't found any info on it throughout the entire internet (because I've read all the internet) is very surprising to me. Unless I'm wrong it appears this is the only way to truly get the throughput necessary for actual RAID performance on a MBP.

> Would I benefit from a RAID 0 array using eSATA
> on my MBP if the single data channel can only
> reach 200MB/s?

Yes. If you already have an ExpressCard/34 eSATA controller with just one port, the OWC eSATA case you linked should work but I am not positive it will be the fastest among the similar looking external SATA cases. A pair of the 1 TB Western Digital Caviar Black drives are what I would currently recommend.

> I'm thinking it would have to hooked up to
> a dual port eSATA adapter and with a dual
> eSATA enclosure such as this or this but
> then again the dual port eSATA would be
> negated because it's all funneled through
> the same data channel -- but of course
> there are no dual enclosures that have a
> single eSATA connection unless it has a
> RAID controller.

I have not seen any tests to really nail down the ultimate top speed of the ExpressCard slot. Barefeats seems to imply it is 200 MB/s because they have gotten over 250 MB/s on a single eSATA channel using PCIe cards in the Mac Pro. If this is the case, a properly designed single port eSATA ExpressCard could be hitting the ExpressCard port bottleneck with two drives in an external case.

> So the alternative to get the real throughput
> needed to benefit from RAID would be to get
> an ExpressCard to FW800 adapter and then
> you have 2 FW800 data channels and can
> effectively RAID 2 FW800 drives..... Am I
> missing something.

A dual channel FW800 ExpressCard is the absolute fastest FireWire option but it will be limited to a maximum of about 145 MB/s under optimal conditions. Apple has removed the ExpressCard slot from all new laptops the but 17" MacBook Pro.


Most of the people I know that have used SSD's are almost addicted to them.
[www.barefeats.com]


They are starting to get cheaper, I expect prices to drop about 33% on most models by next March.



From a Raines Cohen T-Shirt: "The day Microsoft makes a product that
does not suck will be the day they start making vacuum cleaners."

Thanks again for the reply!

That OWC enclosure I linked actually had dual eSATA connections (when I said single channel I meant being the one obvious one ExpressCard slot). I looked over all the enclosures available to me at OWC. They have the:
Triple interface -- FW400, FW800, USB2.0
Quad interface -- FW400, FW800, USB2.0, + eSATA
eSATA interface - dual eSATA ports.

The last is the one I linked to. It seems the Quad interface must have a controller built in since it offers RAID and yet only a single eSATA connection.

I can't afford to go SSD as I need at least 2TB storage and don't have much money. I also don't have a eSATA card so I the option of having dual eSATA ports or single isn't a factor.

Have you heard of this eSATA interface enclosure I linked? I've heard mixed reviews about the RAID controllers, many people claim they use software anyhow and set it to JBOD. In this case would you recommend going for this cheaper eSATA interface adapter?

If I really wanted to spend more money wouldn't I be better off with this RAID 5 Pro setup at OWC [eshop.macsales.com] and get an extra TB?

Which would you recommend or truthfully does it really not matter and comes down to what I want (i.e. all good options for the price)?

So you have no ExpressCard at the moment? It sort of sounded like you already had a single port eSATA ExpressCard.

I would recommend these (the last of the three is the case you already mentioned) with direct connections to each of the drives:
Two drives [eshop.macsales.com]
One dual port eSATA ExpressCard [eshop.macsales.com]
One dual bay case [eshop.macsales.com]
Total about $496

An alternative would be four 500 GB drives and two of the dual bay cases, setting up the drives as RAID 0 in each case. It would use about 60% more power and be less reliable but potentially faster when the array is over 75% full.
Total about $612

FireWire 800 setup:
Two drives [eshop.macsales.com]
One dual port FW800 ExpressCard [eshop.macsales.com]
Two quad interface external cases [eshop.macsales.com]
Total about $530



From a Raines Cohen T-Shirt: "The day Microsoft makes a product that
does not suck will be the day they start making vacuum cleaners."

Thanks you VERY much for this advice... I'm sorry to confuse the situation when I made you think I had a single port eSATA. Because you then suggested enclosures with a control built in and a single eSATA connection I thought you were implying that was better than a dual port enclosure doing to a dual eSATA card. My apologies, with so many variations I wanted to make sure I didn't screw myself.

Thank you again! I'm going to make my final decision now and buy something!

Sorry to chime in late, but I had two things to mention.

First is the ExpressCard. An ExpressCard connects internally with one of two interfaces, USB or PCI Express.

From everything that I've read, it appears that the Sonnet Pro card is the only one to consider, as it is the only one that uses PCI Express. Most (all?) others use USB. Silly, right?

Second is which method would work better: RAID 0 drive enclosure with 1 eSATA channel or dual enclosure with 2 eSATA channels. My gut feeling is that both methods would give similar performance as the bottleneck seems to be the ExpressCard interface, even though it has a theoretical bandwidth of 2.5Gb/s.

My suggestion has to do with the physical aspects, however. eSATA is not the most robust connection method. I've often just shifted an eSATA enclosure slightly and had it disconnect on me. Not unplug, but lose its connection. Another wiggle of the plug and it's back. Could be an issue with my configuration, but my point is that you're going to have the eSATA ExpressCard with one or two cables sticking out of it literally inches from your hands on a daily basis. If you have two cables, it's twice as likely your going to knock one loose. Does anyone know what happens to a RAID 0 volume when one channel is removed? I don't, but I'd tend to believe that it would corrupt the stripe and your volume would be in danger. With one channel, you'd be disconnecting the entire volume which should be safer in that journaling should verify the volume when it's reattached.

Well, I think I'm rambling, but hopefully you get my point. I believe that from a physical standpoint, one channel would be safer.

I'll sit back now and wait for anyone that sees a weakness in my thinking.

Rawdawg-
Something you might want to look into is a ExpressCard eSATA adapter that supports Port Multiplication, such as the FASTA-1ex SATA ExpressCard from CalDigit (no affiliation, just a satisfied customer) - and a multi-bay enclosure, like the Firmtek 5-bay. As Mac Savant said, you will have a high-capacity data interconnect sticking out of the side of your MBP, but that hasn't been an issue for the systems I've set up for editing in hotel rooms and such on Final Cut Pro. You can get enough bandwidth out of them to cut HD, easily twice the bandwidth of FW800.