getting garbage faster using FreeBSD?

Volker volker at
Mon Feb 19 21:10:04 UTC 2007

On 02/19/07 20:51, Kris Kennaway wrote:
> On Mon, Feb 19, 2007 at 08:40:37PM +0100, Volker wrote:
>> The tape sits there since 48 hours writing a block of data every
>> other minute and still didn't fill up the tape completely. The
>> system this is running on is a P-4 3GHz machine using FreeSBIE 2.0
>> (6.2-RELEASE based).
>> I suspect this to be a slow /dev/random.
> This sounds odd to me, I get 18-20MB/sec sustained read performance
> from /dev/random on this 2GHz system, which is probably faster than
> your tape write speed.

Hmm, so this might be the tape drive(r)? I'll check this out as soon
as I'm going to write to hard disk.

I'm going to make some tests with /dev/random to get the real speed.

>> Is there any chance to speed up /dev/random? Would a hifn
>> accelerator card help here to get FreeBSD produce garbage faster?
>> As there is medical data on all media I really need garbage
>> (/dev/zero wouldn't be enough for data security as this might get
>> recovered).
> Neither would a single pass with /dev/random, but you presumably knew
> this.

Yes, I know... I would like to run 5 or more passes if it's not that

Do you think playing with randoms' sysctl interface might influence
performance? Does /dev/random automatically re-seed from time to
time or is it seeded at boot time only?



More information about the freebsd-stable mailing list