dchislop
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Sandisk Ultra problem

Wed Oct 31, 2018 2:19 pm

I recently bought a couple of SanDisk Ultra 32Gb cards on eBay only to find it took about 10 minutes to boot up. I contacted SanDisk who said ............
'Keep in mind that we do not recommend using Sandisk microSD cards as bootable cards, and also this voids warranty, unless you are using a high endurance card like 64GB microSDXC memory card.'

I ran Crystal Disk Mark which is a fascinating tool for checking your read/write speeds and found both cards struggled to read at 20Mb and write at 10Mb. It appears they are fakes !!

As Sandisk do not recommend their cards for booting, I think I'll try the Samsung Evo+ next time.
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jamesh
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 2:40 pm

I'd try buying from a reputable source before anything else. Ebay is rife with fake SD cards - if the deal seems too good to be true, it usually is.
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aBUGSworstnightmare
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 3:14 pm

I'm only using Sandisk Ultra cards on my RPi's (o.k. I have one Samsung EVO too) with not a single issue so far!

gordon77
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 3:25 pm

I use SanDisk Ultra cards all the time on my Pi's, never had an issue with them.

Usually bought in store at Tesco when on offer.

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allfox
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 3:33 pm

I'm using two SanDisk Ultra. One with a Pi 3B, another with a Pi 2. They are labeled as A1 class cards, so designed for running applications with them. No problem.

andrum99
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 5:03 pm

dchislop wrote:
Wed Oct 31, 2018 2:19 pm
I recently bought a couple of SanDisk Ultra 32Gb cards on eBay
<snip>
That's the problem right there - buying SD cards on eBay. As jamesh said, buy from a reputable source to avoid fakes. I've been there, done that myself :oops: If I need to buy an SD card I usually buy from Amazon now, although beware of 3rd party sellers on that platform as well - I would recommend only buying SD cards from Amazon themselves if you go down that route, just to be on the safe side.

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bensimmo
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Re: Sandisk Ultra problem

Wed Oct 31, 2018 5:30 pm

Samsung don't warrant their cards either.

SanDisk Ultra A1 or the Samsung Evo Plus are the two better cards for the Pi as they have the faster small file read and write.
The A1 is at least designed for the OS style using and that's similar to their use in Tablets and Phones as extended (adopted?) storage
I have both manufacturers cards.

As a side the Samsung's (Evo and Evo+, the Evo Plus hasn't yet iirc) keep failing in our mobile phones and tablets (Moto, Lenovo, Huawei) :-(

I only buy mine from Amazon, sold by Amazon.
Never eBay, AliExpress...
Cheap too, £13 gets you the 64GB SanDisk Ultra A1
The 16 and 32 GB (£8.32) are of course cheaper still.
Not worth buying slower cards really or trying eBay deals.

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HawaiianPi
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 4:53 am

dchislop wrote:
Wed Oct 31, 2018 2:19 pm
As Sandisk do not recommend their cards for booting, I think I'll try the Samsung Evo+ next time.
You will find the same thing in the warranty of almost all micro SD cards.

SanDisk Ultra A1 cards work very well for me, although the Samsung EVO+ is good as well. Neither is warrantied for use as a computer boot drive. If you want something that is warrantied to use as a computer boot drive, run your system from an SSD (I have a couple of Pi3 computers booting form SSD with a USB-SATA adapter cable).
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allfox
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 8:06 am

So booting an OS is different than running an application? I don't quite get their points.

CPU works in different privilege mode, how could SD card know this?

Anyway SD cards are cheap, warranty is dispensable.

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Re: Sandisk Ultra problem

Thu Nov 01, 2018 9:25 am

allfox wrote:
Thu Nov 01, 2018 8:06 am
So booting an OS is different than running an application? I don't quite get their points.

CPU works in different privilege mode, how could SD card know this?

Anyway SD cards are cheap, warranty is dispensable.
It's to do with the type of accesses. An OS does lots of small random accesses, usually applications (e.g. cameras) do large serial accesses.
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allfox
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 10:01 am

I read the label said A1 cards could handle more random IO.

So even it's more capable, but still not enough for an OS usage. Nor for an warranty to run OS.

I guess I see it more clearly. Thanks.

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Re: Sandisk Ultra problem

Thu Nov 01, 2018 10:25 am

SD cards have a limited lifetime due to physics behind erase/their write operations, and using one as a 'hard drive' for the OS does hammer that. Some cards are better than others, and by reducing the amount of traffic to the card you can make them last a long time.
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Yukon Cornelius
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 1:50 pm

Those certainly look like fakes that the OP obtained .

SanDisk Ultras have never failed me , and I have a few that are running 24/7 in Pi systems , long-term
with plenty of logging going on .
( I don't care about the warranty . Making a claim would cost more in time alone than buying a replacement ) .

I'm seeing increasing problems in my general repair business that are ultimately rooted in fake hardware .
eg. a Dashcam that I'm convinced came out of the box with a fake sd card fitted

Also , beware of "top-quality" cables from well-known brands , at prices that are too-good-to-miss.
It's rife with HDMI cables .... brand name printed along the cable length , and also molded into the bodies of the connectors ,
( and all the metal parts look right as well ... high-precision ) ..... but they're still garbage , just bin filler in-waiting .

I've cut them apart under a magnifier , and then put the bits under a microscope , and it's very difficult to spot
exactly where the junk factor comes in .
It has to be in the actual materials

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HawaiianPi
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 10:29 pm

Based on the information in the OP, the cards in question were undoubtedly fakes, and none of the concerns in the OP apply to actual A1 cards. Buy from a reputable source and test the cards you receive before using them.
allfox wrote:
Thu Nov 01, 2018 10:01 am
I read the label said A1 cards could handle more random IO.
Not "more" random I/O, faster random I/O.

Random I/O is a performance metric that SD cards have gotten worse at over the years. Modern class 10 cards are horrible at it (some older class 6 cards had better random I/O). Class 10 cards are highly optimized for sequential I/O, because that is the important performance factor in typical SD card use. It became a problem when people started installing smartphone apps on the cards and noticed that performance was much worse than when the app was installed on the phone's built-in storage.

That was good news for our little Pi computers, because the A1 cards also work much better for us, but the demands of running an OS full time are much more than an app that is only run occasionally. So yes, the A1 cards definitely perform better, but do they last longer? Good quality A1 cards should last a long time in a Pi computer, but they won't last forever, so you also need a good backup system.
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Re: Sandisk Ultra problem

Thu Nov 01, 2018 11:04 pm

Beware about fake Sd cards on eBay, just saw a 512 GB one go for $8 in auction. It was a generic class 10. Most likely a fake.
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Re: Sandisk Ultra problem

Fri Nov 02, 2018 3:27 am

andrum99 wrote:
Wed Oct 31, 2018 5:03 pm
I would recommend only buying SD cards from Amazon themselves if you go down that route, just to be on the safe side.
Unfortunately Amazon has something called "stickerless commingled inventory". So even if you buy an item from Amazon there is a risk you will get an item that was sent in by a third party seller.

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Re: Sandisk Ultra problem

Fri Nov 02, 2018 8:38 pm

plugwash wrote:
Fri Nov 02, 2018 3:27 am
andrum99 wrote:
Wed Oct 31, 2018 5:03 pm
I would recommend only buying SD cards from Amazon themselves if you go down that route, just to be on the safe side.
Unfortunately Amazon has something called "stickerless commingled inventory". So even if you buy an item from Amazon there is a risk you will get an item that was sent in by a third party seller.
Hmm. Just googled that. It's not clear from what I have found if Amazon use this for their own stock or just concession stock, although given that the process is to just use UPC and EAN barcodes to identify each item, I'm guessing there would be no distinction between Amazon stock and concession stock of items with the same UPC or EAN barcode. ("Normal" FBA stock all has stickers with X barcodes on them).

Ger_Pa
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Re: Sandisk Ultra problem

Sun Nov 04, 2018 4:27 pm

Just to add another "vote" to the fake Sd card. I mostly use sandisk in various flavours from 8 gb to 128 gb, they may not be the fastest when you compare them to more expensive brands, but they boot raspbian quite fast and they are fast when working with the OS too.

Most likely it's a fake sd card, like everyone else said, don't buy from Ebay. The best thing to do, when buying SD Cards is going to the mfg site and locating official retailers... This i learn the hard way after losing a lot of important data thanks to a counterfeit sd card

dchislop
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Re: Sandisk Ultra problem

Sun Nov 04, 2018 7:26 pm

Thanks for many interesting comments, I think I have learnt my lesson!

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Re: Sandisk Ultra problem

Sun Nov 04, 2018 7:30 pm

dchislop wrote:
Sun Nov 04, 2018 7:26 pm
Thanks for many interesting comments, I think I have learnt my lesson!
Then perhaps the title of the thread should be changed to Fake SanDisk Ultra problem...
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