SxS - SDXC Adaptors.

9 replies [Last post]
steve
Offline
Joined: Apr 8 1999

Can anybody help with this question?
The genuine Sony SxS cards offer guaranteed write/erase cycles, (in thousands), presumably by spreading the data equally over areas and preventing the overuse of certain address ranges, just like SSDs do.
Do the SD adaptors such as the Sony MEAD-SD01 or the 3rd party products like the MxM & MxR manage the write locations in any way, or are they just simple electromechanical interfaces between the SD card and the Express card interfaces?

Steve

SimonMW
Offline
Joined: Nov 16 2004

They are just adaptors.

Alan Roberts
Alan Roberts's picture
Offline
Joined: May 3 1999

Does that mean that they just connect the pins of the card to the sockets of the adaptors? Or is there hardware/software between? That's the real question.

'Proper' card management makes sure that all storage cells are more or less equally used, even to the extent of moving the boot sector around. In P2, this control is in the card itself. I believe that in SD cards, it isn't. But I'm not sure. And I don't know the details of SxS cards.

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

steve
Offline
Joined: Apr 8 1999

Thanks Simon. That's a shame but i suppose Sony wouldn't want to undermine the SxS's USP (just like Panasonic with P2) and the MxM and MxR carriers are too cheap to include management electronics.
Maybe we'll see the flash cards themselves with local management functions on chip offered one day, - a sort of SD Pro range.
It says in various places that the interface between the host (PCI Express) and the flash card is only USB. This is slower than the 34pin PCI Express interface but also a lot cheaper. That's the main reason why Sony and others don't recommend overcranking to them, even though a class 10 card should be able to handle the data easily.

Steve

infocus
Offline
Joined: Jul 18 2003
steve wrote:
Thanks Simon. That's a shame but i suppose Sony wouldn't want to undermine the SxS's USP (just like Panasonic with P2) and the MxM and MxR carriers are too cheap to include management electronics.
Maybe we'll see the flash cards themselves with local management functions on chip offered one day, - a sort of SD Pro range.

Compact Flash has a controller built in to each chip already (I suspect SD may be the same), so it's wrong to think of them as just memory gates, controlled externally. The controller does such functions as "wear levelling" (see http://en.wikipedia.org/wiki/Wear_leveling ) which aims to even out the read/write cycles over all the locations on the chip. It also performs error checking, and if it detects bad blocks on the chip will reassign the data to a different block.

Such functions are far from unique to P2 - though Panasonic marketing would like you to think differently.

What is different with P2 or SxS systems is that the "intelligence" is taken a stage further, doing read/write verifications and they are able to be even more robust under certain conditions. (Such as after a sudden power loss.) The big difference is that with P2, this "intelligence" is intrinsically within the card, with SxS it's mostly within the camera. It performs similarly in each case, but the advantage of the SxS approach is that it only needs to be paid for once (as part of the camera), with P2 it needs to be paid for with every card.

This is one big reason why using SDHC with a simple adaptor is possible for SxS, not for P2 - the "intelligence" is there as part of the SxS camera already. It may be possible to get adaptors eventually to use SDXC cards in a P2 sized adaptor, and I know Panasonic are very keen to make it happen. It needs SDXC performance speed to increase substantially before it can, and will mean the adaptor will then need the extra "intelligence" that currently is in the P2 cards. (So don't expect the adaptors to be as cheap as SxS ones.)

drc_online
Offline
Joined: Apr 19 2010
Alan Roberts wrote:
Does that mean that they just connect the pins of the card to the sockets of the adaptors? Or is there hardware/software between? That's the real question.

Yes, that's exactly what it is Alan. Two connectors joined by a circuit board that has no components on it.
In fact they are just routing the power and the two USB signal connections.

The only drawback of these type of adapters is that because they swallow the SDHC card completely, there's no way to operate the write protect switch on the original SDHC card without removing the card again, which loses some of the benefit of protecting the more fragile card.

I would always feel more comfortable enabling a write-protect switch on solid-state media before plugging it into a card reader!!!

Dave

rone01
Offline
Joined: Feb 9 2009

Yes there will always be draw backs on cheaper media and/or adapters - we discuss this a lot, seems to take a lot of getting through (not yourself) as people just see £££. No free lunch.

As for 'intelligence' I understand the camera closes off the recording cycle on P2 systems every two seconds. I don't think this is a facet of the card. Though there is plenty going off in the card as has been said.

Get what you pay for with recording media IMHO!

@ Infocus - where did you get the news Panasonic are keen to make it happen?

Red EPIC / Scarlet - Panasonic AC 90 -  besq.co.uk

infocus
Offline
Joined: Jul 18 2003
rone01 wrote:
@ Infocus - where did you get the news Panasonic are keen to make it happen?

From independent dealerships typically – it seems generally accepted that the ability to use full spec OR consumer media in such a camera is seen as extremely good in sales terms and that Panasonic are only too aware of the situation. Does that surprise you? It may not be applicable to you – but to a lot of people it’s a deal maker.

rone01 wrote:
Yes there will always be draw backs on cheaper media and/or adapters - we discuss this a lot, seems to take a lot of getting through (not yourself) as people just see £££. No free lunch.

No, it’s not just £££, though for some users, cheaper media may mean a saving that can be put towards a better quality camera. And it may not apply to you – but for other users it can make a huge difference in workflow. Can make solid state viable, whereas SxS/P2 prices may mean staying with tape.

You’re also ignoring the workflow possibility of being able to hand over the original media to a producer at the end of shoot. Ignoring being able to clone cards in camera. Ignoring risks of having to download in less than ideal conditions to free up card space.

I’ve had such discussions with a number of people, and whilst (like yourself) not all have the need or desire to use consumer media, you are the only one who can’t see why it may be a highly desirable feature in principle.

rone01 wrote:
Get what you pay for with recording media IMHO!

But what are you paying for? This whole thread started with Steve asking ” The genuine Sony SxS cards offer guaranteed write/erase cycles, (in thousands), presumably by spreading the data equally over areas and preventing the overuse of certain address ranges, just like SSDs do. Do the SD adaptors …………….. manage the write locations in any way,…….” Which implies that you have to pay the SxS/P2 premiums to get features such as wear leveling. And that’s not true. Consumer memories such as CF/SDHC have their own on-board controllers, and to get an idea of the sophistication, just look at http://en.wikipedia.org/wiki/CompactFlash . For example:

Quote:
When using CompactFlash in ATA mode as a hard drive replacement, wear leveling becomes critical. The advanced CompactFlash controllers spread the wear-leveling across the entire drive allowing all blocks to participate. The more advanced CompactFlash controllers will move data that rarely changes to ensure all blocks wear evenly....................

For reads, the onboard controller first powers up the memory chips from standby. Reads are usually in parallel, error correction is done on the data, then transferred through the interface 16 bits at a time. Error checking is required due to soft read errors. Writes require powerup from standby, wear leveling calculation, a block erase of the area to be written to, ECC calculation, write itself.............

The currently used NAND[18] flash has an endurance of 1,000,000 writes[18] per location (less reliable than magnetic media) before hard failure and is prone to frequent soft read errors.[19] The CompactFlash card includes error checking and correction (ECC) and wear leveling circuitry that is transparent to the user, although it may slow data access.

Get the idea? I’m not disputing there are some advantages to such as P2 or SxS, but far less significant than much advertising would have you think. A lot of what people think they’re paying the difference for actually comes as standard with such as CF – wear leveling being the obvious example. Yes, the more expensive cards are faster, but does it matter to most users, as long as the card is “fast enough”? Have one SXS card for overcranking, yes, but why do most people need lots of fast cards?

Alan Roberts
Alan Roberts's picture
Offline
Joined: May 3 1999

The advantage of fast cards is much less to do with shooting than with the speed of getting the stuff off the card. The faster the card, the quicker the down-load. It's all down to work-flow. The recording over-crank abilities are much less important to most people, but fast ingest into the editor can be really useful to everybody..

Get my test cards document, and cards for 625, 525, 720 and 1080. Thanks to Gavin Gration for hosting them.
Camera settings documents are held by Daniel Browning and at the EBU
My book, 'Circles of Confusion' is available here.
Also EBU Tech.3335 tells how to test cameras, and R.118 tells how to use the results.

infocus
Offline
Joined: Jul 18 2003
Alan Roberts wrote:
The faster the card, the quicker the down-load. It's all down to work-flow. .......... fast ingest into the editor can be really useful to everybody..

It's impossible to give general figures, but whilst the above is true theoretically, practically the weakest link seems to be somewhere other than the card. Paying a lot more to get a far faster card may result in not that much better performance.

My memories from testing P2 in it's earliest days (with DV25) was a download speed of about 4-5x realtime (so just over 100Mbs) with the card plugged directly into the PCMCIA slot of a fast laptop, and downloading to an external hard drive. I believe this sort of performance was fairly typical for a lot of users.

Yes, it depends on all sorts of factors, and the performance of what it's going onto, and some systems will do far better than that. But it's worth being aware that paying for a card with a nominal read speed 10x faster (say) is extremely unlikely to mean downloads will be anything like that factor faster. In the worst cases there may be little difference.

Amongst the high price/high spec cards (P2/SxS) it's also worth bearing in mind that whilst some laptops have ExpressCard slots, virtually no new machines now have the Cardbus slots on which P2 is based. Consequently, you may be able to plug an SxS card directly into the laptop, a P2 card will likely need an external adaptor. Quite apart from convienience, that's likely to give the SxS card a download speed advantage, independent of the rated card speed.