[Etherlab-users] Best filesystem for DLS?

Dr.-Ing. Wilhelm Hagemeister hm at igh.de
Tue Mar 23 17:30:47 CET 2021

Hi Sebastien,

increasing the number of inodes helps.

dumpe2fs -h /dev/sdxx helps to see what are your limits now.

Regarding dls please check, if you get restarts of the sampling
processes due to sample time constrains. Usually this is the case with
data sources form realtime processes with high jitter. This results in
creating new chunks (and a lot of new files). So have a look in your
channel directory (or in dlsgui) if you have lots of chunks which have a
breaks of only a few seconds.
Also you get a log entry in your messages (or journalctl) saying
something like: "Time diff of xxx us (expected xxx us, error is percent
xxx %)"

Also increasing the numbers for blocksize and reduction in the channel
setup decreases the number of files.

Are you sampling constantly or just small chunks with a trigger for your
job? If later is the case, try to increase chunksize by constant
sampling over longer periods.

"btrfs" and "xfs" have no inode limitation but we have no experience
with that.

Regards Wilhelm Hagemeister

Am 23.03.21 um 17:05 schrieb Merkel, Amos:
> Hi,
> I have never tried, but couldn't you simply manually define a
> higher bytes-per-inode ratio with mkfs.ext4 -i ? 
> Arch-Wiki has some explanations on the topic:
> https://wiki.archlinux.org/index.php/Ext4#Bytes-per-inode_ratio
> <https://wiki.archlinux.org/index.php/Ext4#Bytes-per-inode_ratio> 
> Greetings,
> Amos 
> ------------------------------------------------------------------------
> *Von:* Etherlab-users <etherlab-users-bounces at etherlab.org> im Auftrag
> von blanchet at iram.fr <blanchet at iram.fr>
> *Gesendet:* Dienstag, 23. März 2021 16:35:28
> *An:* etherlab-users at etherlab.org
> *Betreff:* [Etherlab-users] Best filesystem for DLS?
> Hi,
> Short version:
> -------------------
> What is the best filesystem for DLS data ?
> Long version:
> -------------------
> I am running DLS to archive a lot of signals (about 20K), and I am
> facing an issue with the number of files.
> I have a 1TB EXT4 filesystem to store the data. It is 50% full but there
> is no more free inodes, because DLS creates many files and directories.
> According to the output of “df -i”, DLS has already created about 78M of
> files.
> I understand that I have to switch to another filesystem that supports a
> bigger number of files.
> And I wonder, what is the best filesystem for such a case.
> Regards,
>> Sebastien BLANCHET
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