What FS for a SD-Card is the best?

SarahS93 · l33t Joined: 21 Nov 2013 Posts: 693

I have a SanDisk Extreme Pro 256 GB SDXC SD-Card (95 MB/s, Class 10, U3, V30) (95 MB/s read and 90 MB/s write)
My SD-Card Slot in my Lenovo x121e Notebook is connected by PCIE.

What is the best way to test how fast the SD-Card is?
With the preformatet exFat mounted with Fuse, i only have ~30MB/s writespeed.
Is that normal?
What FS must i use?
Is there any special that i have to do with fdisk?

Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

SD cards are designed as cheaply as possible under the assumption that they'll only ever be used under win32, with the default filesystem drivers. The Linux exfat driver probably has very different access patterns. You may be better off using UDF.

NeddySeagoon · Posted: Fri Jan 26, 2018 8:14 pm Post subject:

SarahS93,

FUSE filesystems are slow because of all the userspace/kernelspace context switches.
Its a design feature.

What data will you put on the SDCard?

For speed, journaled filesystem are best avoided but if you ever need a fsck after an unclean shutdown, it will take a long time as there is no journal to replay.
What other devices need to read/write the filesystem?
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

SarahS93 · l33t Joined: 21 Nov 2013 Posts: 693

I will download and store files from the internet on it
I download with ~25MB/s. The download programm (JDownloader) download a file, read the file to create and compare the checksum of it.
I need 4 files with 2 connection per each file for the best download speed.
If i write on my small SSD, all is OK, but only the space is sometimes not enough.
So i decided to buy a SD-Card, because more space and easy to put out of my Notebook and into my desktop computer for transfer the files from the SD-Card-Reader to my Desktop HDD.
If i write and write to the SD-Card at the same time (more files, ~4..5 files) the download speed goes down for some moments.
So i must download to the SSD and transfer from there to the SD-Card (by useing exFat with Fuse)

I have do some test myself with differnt Filesystems

saboya · Guru Joined: 28 Nov 2006 Posts: 552 Location: Brazil

F2FS maybe?

NeddySeagoon · Posted: Fri Jan 26, 2018 9:45 pm Post subject:

SarahS93,

You need to use bs=1M at least, with dd or most of the time goes into context switching.
SDcards also have a 4k physical block size, so writing 1k blacks is a bad thing.

There are several filesystems intended to get the best out of FLASH memory. Its worth trying some of these.
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

SarahS93 · l33t Joined: 21 Nov 2013 Posts: 693

Why does SanDisk write on the SD-Card "95 MB/s read and 90MB/s write"? Are these true at Windows-Systems?
What do you think is the best write MB/s that i can get in Linux with these SD-Card?

I will try F2FS and post my results.

NeddySeagoon · Posted: Fri Jan 26, 2018 10:39 pm Post subject:

SarahS93,

If you use a FUSE filesystem 30MB/sec is pretty good.

You need a filesystem from the kernel.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

SarahS93 · l33t Joined: 21 Nov 2013 Posts: 693

With F2FS, i have no stops in my downloads and read files for the checksum, it works good.

Goverp · Veteran Joined: 07 Mar 2007 Posts: 1995

FWIW I've been using F2FS on a Raspberry Pi running (on Arch Linux) (a) a CUPS print server (b) a Radicale CALDev server for very nearly a year now, running 24x7. It's been rebooted a few times after applying service and suffered a few power cuts causing a restart. No problems so far.
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beandog · Posted: Tue Feb 06, 2018 11:37 pm Post subject:

beandog · Posted: Tue Feb 06, 2018 11:38 pm Post subject:

For all my flash devices, I mount them with "sync" option, because I hate that "lulz we just copied 20 GBs in one second, and then unmount takes three months." *rage*

That's probably not safe, but that's never been my big concern anyway since I like to break things.
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Ant P. · Watchman Joined: 18 Apr 2009 Posts: 6920

pjp · Administrator Joined: 16 Apr 2002 Posts: 20067

Moved from Multimedia to Kernel & Hardware. Given the subject is primarily SD-Card related and not a sound or video issue, seems to fit better with Hardware.
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