Nautilus disk cache behaviour

Narcis Garcia informatica at actiu.net
Wed Jul 15 09:44:57 UTC 2015


Although dilesystem/device write cache is a kernel level feature,
userspace tools can ask kernel for syncing.

I suppose in UG 32-bit UG variant it's kernel responibility to not apply
write cache for USB block devices, but in UG 64-bit write cache is
working for those cases.

When write cache is working, Nautilus calls some sync at end of copying
files. You can reproduce it with UG 14.04 (64-bits):
1. Plug an USB pendrive (4GiB or more)
2. Copy there files bigger than 1GiB, from a faster volume (hard disk p.e.)

You will see a reasonable speed from 1% to 99%, but at the end you will
see Nautilus talking about 0 seconds remaining during large time. When
Progress dialog closes, pendrive activity finishes inmediately.
That "large time" lapse only can be the sync task.


El 15/07/15 a les 10:57, Tim ha escrit:
> 
> 
> On 15/07/15 18:51, Narcis Garcia wrote:
>> Hello,
>>
>> I've seen that in Ubuntu-Gnome 14.04 (32-bits), when copying files from
>> internal device to USB store (such as pendrive), disk write cache is not
>> working.
>>
>> In Ubuntu-Gnome 14.04 (64-bits) disk write cache works (it's better),
>> but at the end of copy progress bar cache is synced, and I feel is
>> convenient to wait before doing more write operations.
>>
>> My question:
>> Is there any way to configure Nautilus to not sync write cache at any
>> time (only when umount, of course)?
> filesystem write cache is a kernel level feature, I seriously doubt nautilus has any knowledge of that!
>>
>>
> 
> 



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