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Re: [gpsd-users] 1PPS NOW working with RPi 3 B+ and Stretch

From: Paul Theodoropoulos
Subject: Re: [gpsd-users] 1PPS NOW working with RPi 3 B+ and Stretch
Date: Sun, 5 Aug 2018 00:02:49 -0700
User-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.0

A quick followup on this, since it's not _directly_ germaine to gpsd, but it can be useful info.

My most reliable SD cards so far have been...Patriots! I bought individual ones more than a year ago. They are fast, overclock better than any of my other SD cards, and I've never experienced corruption (knock wood). So who knows what happened with yours - a bum batch, damaged in shipping, we'll probably never know.

I'll add that I had mentioned the Silicon Power SD cards that I'd recently bought. They have been trouble-free so far, however - the Raspi actually *underclocks* them from the default 50MHz bus down to 25Mhz! I cannot run them at standard or overclocked, at all, so needless to say, performance is poor.

I've been doing my own set of benchmarks similar to those Jeff Geerling has published -

And I'm finding similar results, although the Patriot cards are coming up nearly in the same cohort as the good ones he's listed.

I've sort of focused on the lesser (translation: cheaper!) brands, even knowing they generally are unlikely to perform as well (testing is still ongoing).

Don't know if the chart below will render properly to the list or not. If not, I can post elsewhere if there's interest.

Card Make/Model
Bus speed
hdparm buffered
dd write
4K random read
4k random write
Patriot LX 16gb SDHC Class 10 UHS-1
100 MHz
36.7 MB/sec
8.1 MB/s
8.06 MB/s
3.80 MB/s
Sandisk Ultra 16gb SDHC Class 10 UHS-1 A1
50 MHz
22.7 MB/sec
17.1 MB/s
8.08 MB/s
2.20 MB/s
Sandisk Ultra 16gb SDHC Class 10 UHS-1 A1
83 MHz
37.0 MB/sec
17.9 MB/s
9.38 MB/s
2.22 MB/s
Sony 16gb SDHC Class 10 UHS-1 
83 MHz
35.3 MB/sec
9.2 MB/s
5.9 MB/s
0.26 MB/s
Transcend 16gb SDHC Class 10 UHS-1
83 MHz
37.0 MB/sec
15.5 MB/s
8.65 MB/s
1.53 MB/s
Silicon Power 16gb SDHC Class 10 UHS-1
25 MHz
11.4 MB/sec
10.3 MB/s
3.55 MB/s
0.69 MB/s
Transcend 8gb SDHC Class 6
50 MHz
17.1 MB/sec
11.6 MB/s
gave up
gave up
Kingston 16gb SDHC Class 10 UHS-1
83 MHz
34.4 MB/sec
9.6 MB/s
5.37 MB/s
0.45 MB/s

On 7/29/2018 14:05 PM, Alan Scott wrote:


I purchased Patriots also from amazon got the 5 pack of them.

Yes they are very reasonably priced, but ANYTHING COULD have happened to those cards, even after arriving in my possession, and face it, I have a LOT of MAG mount antenna laying around here, so I simply am going to suggest this, and I will defer to GEMiller for a "correct" or MORE-correct than simply scribbling zeros or random data across the card prior to any use or re-use, I personally could care less about "burning" a write session on the card........face it at some point THEY ALL WILL FAIL.  So weather it fails today, or tonight because I "burned" one Read/Write session on it, I could care less, this is why I carry backups......(enough about best practices)......


On 07/28/2018 01:25 AM, Paul Theodoropoulos wrote:
On 7/28/2018 1:03 AM, Alan Scott wrote:

There is nothing whatsoever wrong with the "clockmaker" script / build recipe.......As gemiller said to me in an email it's very probable that I got a batch of "bad" micro SD cards because the exact same recipe failed after attempting on 4 separate but "brand new" micro SD cards, same brand, same source, same shipping method all together in the same package and even stored by myself in the same container / what ever may have effected one of them p

Hi Alan,

Would you be willing to share the brand/source/specifics of the cards that were bad? Never hurts to be able to scratch something off the list of potential purchases if they have a high failure rate.

Myself, I have both "Patriot" brand and "Silicon Power" brand in use on my Raspi's, with no confirmed failures (the "Patriot" ones in service for over a year, the Silicon Power ones in use only a few weeks, but no issues thus far). Got both brands on Amazon, 16gb sized (only because 16gb seems to be the sweet spot for having current/good specs and great prices - often less expensive than the 8gb's.)
Paul Theodoropoulos

Paul Theodoropoulos

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