Architect1776 Loc: In my mind

The question is strictly for those cameras with identical cards not mixed cards, you can start your own thread for mixed cards.
Thank you

jerryc41 Loc: Catskill Mts of NY

I generally leave the cards where they are. I save the pictures to both cards, so they get equal use. I like the idea of the same pictures in two places.

"...so they do not need to comment." "Need to" and "want to" are two entirely different things.

Architect1776 Loc: In my mind

gvarner Loc: Central Oregon Coast

I shoot RAW on one and JPEG on the other because I would have casual snapshots that wouldn’t need any PP and would just use the JPEG for those. Now I do the casuals with my smartphone but still do the RAW/JPEG thing.

JimH123 Loc: Morgan Hill, CA

Understand that memory cards are not ideal long term storage options. NAND flash has a floating gate that either has no charge or a negative charge with just a few electrons. This charge can slowly bleed off over a few years causing a loss of data.

Cards do have a spec that gives a max storage period of something like 10 years.

The older cards (single level cells, lower capacities and lower speeds) had larger gates and stored more charge and tended to wear out slower and hold charge longer. The newer cards (multi level cells, higher capacities, higher speeds and much longer page sizes) had everything scaled down in size resulting in fewer write/erase cycles and shorter max storage life. That's the price we pay to have these newer features.

FYI: Wear out is based on Write/Erase cycles. Read operations are not part of the wear out process. You can re-read the same card as many times as you want at no cost to wear out. Also, I have heard people claim that reading refreshes the card. This is not true. This is not DRAM. When data is written, that's the only time the gate is injected with electrons.

Architect1776 Loc: In my mind

How fast do cards really wear out from read/write cycles.
I have 20 year old cards that work as good today as they did 20 years ago and they get written to and erased all the time. One card failed about 17 years ago but assumed that it was defective as the other 5 cards are still going strong.
So again what is the life of a card writing and erasing?

jerryc41 Loc: Catskill Mts of NY

My M.1 - Total Write: 10,880 GB, 97% left, according to CrystalDiskInfo

JimH123 Loc: Morgan Hill, CA

The cards from 20 years ago had much larger transistors and gates and were more hardy. They had much larger max figures for write/erase cycles. Perhaps 10x longer.

But those older cards had much lower capacities too.

As for your question, NAND Flash is structured in Blocks. And within a Block is some number of pages. Erase and write is done one block at a time. If you have older data living in another Block, that Block is not refreshed when you write new data to a different Block.

During erase, the whole Block is erased as one operation. And then data is written, one page at a time. Actually, there is RAM memory for the page that is first loaded, and then the whole page is written in parallel. And then on to the next page.

By making pages longer, the write speed of the memory can be made faster. The old memory cards used a page size of 512 bytes (called Core Memory) and some additional space (called Spare Memory - which holds additional information needed). Newer memory has increased that page size (a lot) and has also come up with multiple pages where data is distributed between core arrays, where multiple pages can be written in memory in parallel. Plus, the individual cells have gotten so small that errors are common so the spare area has also grown to hold info needed to do Error Correction within a page. Suppose you have a page size of 16K bytes, and the spare area hold in excess of 2K bytes. The extra data in the spare area is then used to detect and correct a certain number of bad bits within the Core Memory. The details for this are very guarded and vary from supplier to supplier and some can correct more bad bits than others.

As the block ages, certain bits are going to start to fail. And as they fail, Error Correction will mathematically detect and correct a certain number of bad bits on that page, and you the user will never be the wiser that you actually have bad bits that were fixed on-the-fly during a read operation. The manufacturer is likely never going to tell you how many bad bits it can correct and how many it has used up on any given page.

Before I retired, I was involved in writing test programs for these memory devices, and during test, we could determine this information at wafer level. But after the die are built into finished packages, the internal memory manager has no access to this information for the end user.

 

Architect1776 Loc: In my mind

Thx

Rab-Eye Loc: Indiana

I use slot 2 as backup. I never swap cards because my camera uses #1 for video, so I keep a v90 card in slot 1.

junglejim1949 Loc: Sacramento,CA

That is the beauty, set up as you wish!

mwsilvers Loc: Central New Jersey

I indicated what I do on in the third post on page 2 but I will repeat it here.

On my cameras with two identical card slots I always leave one card in a slot fairly permanently, and just remove the other card when needed. I use the permanently installed 2nd card as a backup of the first and capture fine large jpegs and raw files to both.

In my explanation on page 2, I forgot to add that after downloading the images to my computer, culling them and backing them up, I will usually reformat both cards in camera. However, I may occasionally put reformatting off for some period of time after a shoot that is very important to me in case I decide I want to redownload any culled images. I see no advantage swapping cards from one slot to the other.

User ID

Where I have one slot, I fill it. Where I have two, they are not alike, so its EZPZ. Where I have three, I start a troll thread like this one.

TriX Loc: Raleigh, NC

I shoot raw on card 1 and JPEG on card 2. Since the JPEGs are for quick, unedited use, I typically download to a tablet or laptop via WiFi so I never remove the card. I typically remove card 1 (raw) and read it in a fast USB reader for post processing, so I make no effort to equalize the number of writes or slot uses. I only format when the particular card gets maybe 70-75% full, not every time I remove it. The net net is that since SD cards support so many write/erase cycles, I just never worry about it, and I see no need to format each time unless it helps you keep the new content separated from the old. This is only my workflow, not a recommendation.

bnsf

I have 2 SD cards installed in the Sony a99ii camera. I use card 1 for photos and card 2 for videos. This way I do not have to transfer the videos on card 1 to card 2. Card 1 and card 2 are both 128gbs.
So far I have no problem using the cards setup for photos and videos. Just wish the Sony RX10M4 had a 2 card slot.