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Understanding Memory Cards

photographylife.com

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Re: Understanding Memory Cards

#11

Post by gruez »

Sharlin wrote: post #6

It’s such a ridiculous dark pattern to only advertise read speed when in almost all cases write speed matters more. Also, the SD speed class notation is almost totally obsolete and anachronistic because these days even the fastest class 10 has a minimum speed requirement so low it tells you almost nothing about the card’s performance.

> Also, the SD speed class notation is almost totally obsolete and anachronistic because these days even the fastest class 10 has a minimum speed requirement so low it tells you almost nothing about the card’s performance.

There are higher speed classes past class 10.

https://en.wikipedia.org/wiki/SD_card#Class

Re: Understanding Memory Cards

#12

Post by dkdklk »

vardump wrote: post #10
verall wrote: post #4

This is an extremely verbose article, but for most people I would highlight the most important things (for SD cards at least): Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. Buy from a real retailer: this means B&H or Adorama or a not-shady brick and mortar store. Amazon will happily ship you counter…

> Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. I've had always bad luck with Sandisk, both CF and SD/microSD cards.

Buying from Amazon? You’re likely getting fakes. Genuine SanDisk memory cards are top notch.

Sure every brand will have lemons, but if you’re seeing consistently bad “SanDisk” cards.. you are pretty certainly not getting genuine product. Find a reputable supplier (which is absolutely not Amazon)

Re: Understanding Memory Cards

#13

Post by Jolter »

goblin89 wrote: post #9
verall wrote: post #4

This is an extremely verbose article, but for most people I would highlight the most important things (for SD cards at least): Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. Buy from a real retailer: this means B&H or Adorama or a not-shady brick and mortar store. Amazon will happily ship you counter…

I haven’t had too many issues ordering from Amazon, but I go through much effort making sure seller is reputable every time and listing was not swapped. Both Adorama and B&H sell on Amazon too, but for photo/video gear I would go to B&H direct.

Amazon will swap in fakes no matter what seller you're using, as long as they're using Amazon's fullfillment services. Search this site, there is like one article a month about it.

Re: Understanding Memory Cards

#14

Post by khedoros1 »

gruez wrote: post #11
Sharlin wrote: post #6

It’s such a ridiculous dark pattern to only advertise read speed when in almost all cases write speed matters more. Also, the SD speed class notation is almost totally obsolete and anachronistic because these days even the fastest class 10 has a minimum speed requirement so low it tells you almost nothing about the card’s performance.

> Also, the SD speed class notation is almost totally obsolete and anachronistic because these days even the fastest class 10 has a minimum speed requirement so low it tells you almost nothing about the card’s performance. There are higher speed classes past class 10. https://en.wikipedia.org/wiki/SD_card#Class

Not in the sense of a "C" surrounding a larger number than 10. Instead, you get a card marked with all of "C10", "U3", "A2", "V60", or some crap like that.

Give me 4 numbers: Read and write speeds, each in terms of minimum sustained transfer rate and minimum random IOPS.

Re: Understanding Memory Cards

#15

Post by barrkel »

vardump wrote: post #10
verall wrote: post #4

This is an extremely verbose article, but for most people I would highlight the most important things (for SD cards at least): Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. Buy from a real retailer: this means B&H or Adorama or a not-shady brick and mortar store. Amazon will happily ship you counter…

> Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. I've had always bad luck with Sandisk, both CF and SD/microSD cards.

I've never had a SanDisk failure in over 10 years. At one point I was recording two hours of 1080p video a day, rotated between three cards, for a couple of years.

Re: Understanding Memory Cards

#16

Post by jagger27 »

dkdklk wrote: post #12
vardump wrote: post #10

Earlier quoted context omitted.

> Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. I've had always bad luck with Sandisk, both CF and SD/microSD cards.

Buying from Amazon? You’re likely getting fakes. Genuine SanDisk memory cards are top notch. Sure every brand will have lemons, but if you’re seeing consistently bad “SanDisk” cards.. you are pretty certainly not getting genuine product. Find a reputable supplier (which is absolutely not Amazon)

The general advice for buying off Amazon it to make sure that it's actually coming from Amazon.com, not CheapMemoryAmerica1999.

Re: Understanding Memory Cards

#17

Post by jagger27 »

mikehollinger wrote: post #5
verall wrote: post #4

This is an extremely verbose article, but for most people I would highlight the most important things (for SD cards at least): Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. Buy from a real retailer: this means B&H or Adorama or a not-shady brick and mortar store. Amazon will happily ship you counter…

Yup. The street bazaar in Amazon is quickly turning into a hawkers market where you have to know you’re buying a fake Rolex and negotiate accordingly. The problem is that no one in the general public knows this. A cursory glance around AliExpress shows SD cards with “decorative” labels - and straight up fakes. The problem you get is that any joe blow can buy from Ali- resell on Amazon or elsewhere - and be truthful i…

Small anecdote, but I have had success buying accurate capacity Samsung microSD cards on AliExpress. Just pick the seller with the most sales.

Re: Understanding Memory Cards

#18

Post by 3xblah »

verall wrote: post #4

This is an extremely verbose article, but for most people I would highlight the most important things (for SD cards at least): Buy a real brand: people have there own opinions on this, but to me this means Sandisk, Samsung or Verbatim. Had a bad experience with Lexar once but as always ymmv. Buy from a real retailer: this means B&H or Adorama or a not-shady brick and mortar store. Amazon will happily ship you counter…

https://kb.sandisk.com/app/warranty

I tried a couple of FAT32 formatted 16GB SanDisk microSD that have a "Lifetime" warranty in an OpenWRT-based router that has a microSD card slot. I managed put them both into unrecoverable "read-only" mode by letting some daemon write to them unconditionally.

They were purchased from a large electronics retailer not Amazon.

I normally do not use SD cards or USB sticks for non-interactive, frequent writes. I usually write to them manually (i.e., interactively), either storing files or dd'ing bootable images. For example, I am not one of those people who tries to use an SD card as a substitute for a HDD in an RPi. I only use tmpfs for non-interactive writes.

Is there any reason I should not conclude that these cards are not suitable for high frequency and high volume of writes.

Re: Understanding Memory Cards

#19

Post by goblin89 »

Jolter wrote: post #13
goblin89 wrote: post #9

Earlier quoted context omitted.

I haven’t had too many issues ordering from Amazon, but I go through much effort making sure seller is reputable every time and listing was not swapped. Both Adorama and B&H sell on Amazon too, but for photo/video gear I would go to B&H direct.

Amazon will swap in fakes no matter what seller you're using, as long as they're using Amazon's fullfillment services. Search this site, there is like one article a month about it.

I keep hearing stories but am yet to be burned with a fake myself. Perhaps paying attention to the seller and the listing makes a difference after all (I don’t know how others do it), or Amazon US uses different procedures when shipping internationally, or I’m just lucky and haven’t been buying that much (fewer than ten tech items in an average year).

If anyone chooses to order memory cards or the like from Amazon US specifically for whatever reason, I find that at least an hour reading reviews and surveying listings is required for me personally to be reasonably hopeful I will get what I want. Trying to spot dishonest reviews or signs that older reviews are for a different product (swapped listing). I imagine if I were in the US I could simply order multiple product variations from different listings & sellers and then pick the most genuine-looking one, returning the rest, but that would be a major hassle when ordering overseas.

Re: Understanding Memory Cards

#20

Post by ungzd »

Is there any real difference between SD, SDHC and SDXC, aside "SD uses FAT, SDHC uses FAT32, SDXC uses ExFat"? These cards does not have filesystem controller on it, it's not "FTP over wire", it's block-based storage device. If I format ancient SD from early 2000s with exFat, will it become SDXC?

From Wikipedia (marked with "Citation needed"):

> The SDHC format, announced in January 2006, brought improvements such as 32 GB storage capacity and mandatory support for FAT32 filesystems.

How dumb storage device can refuse to support FAT32?

Fun fact: SD cards support SPI interface and can be easily connected to cheap microcontrollers.

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