Re: [Discuss-gnuradio] File sink causes "S" errors

[Tom Rondeau]

On Tue, Oct 5, 2010 at 10:10 PM, Josh Blum <address@hidden> wrote:
> Can you benchmark your hard disk for sustained rate?
>
> I don't think that most disks, even SSD,s can sustain a write rate of 25Msps
> @ 4 bytes a sample (if you are capturing shorts) = 100MB/s
>
> -Josh
>
> On 10/05/2010 06:35 PM, Thomas Hobiger wrote:
>>
>> Hi everybody,
>>
>> I am running a USRP2 with a DBSRX and talking to the hardware via raw
>> ethernet. Running GRC goes well (e.g. doing a real-time FFT spectrum),
>> but when I start recording on disc I get many "S" messages ("2
>> successive packets which do not have 2 successive sequence numbers")
>> after about 10 seconds. I am currently sampling with a decimation of 4,
>> but the problem remains with other decimation factors as wekk, just the
>> messages show up slightly delayed. I think the HD itself is not the
>> reason as I am recording to a 80 GB SSD, which has EXT4 and is mounted
>> in a quite fast mode (I have benchmarked the I/O giving me much more
>> bandwidth than what streams in from the USRP2).
>> I have started to modify parts of the GNURADIO code, but changing buffer
>> sizes does not help much.
>>
>> Is there anybody who experienced similar troubles?
>>
>> Regards,
>> Thomas Hobiger

Josh is probably right about this: sustained throughput at that rate
to anything, even an SSD, is unlikely.

Anecdotally, I found that JFS provided me with higher throughput, but
only by a few % points, which I don't think is going to do it for you.

Tom