[nycbug-talk] File Backed Disks- Speed Issues

[Isaac Levy]

Hi All,

Wow everyone had constructive responses- though I don't know why I'm  
surprised, nycbug talk list always rocks,

On Sep 28, 2006, at 3:17 PM, Trish Lynch wrote:

> On Thu, 28 Sep 2006, Isaac Levy wrote:
>
>> During the FreeBSD 4.x days, (wow what an era), file-backed disks
>> were snappy, with little overhead, no? (vn(4) and vnconfig(8),
>> respectively)
>>
>> --
>> In the immediate future, I'm taking some jailing systems back to just
>> running jails on the filesystem, (and partitioning, yuck), but in the
>> meantime does anyone have any thoughts on the subject?  It simply
>> seems like the file-backing part of the memory disk implementation
>> was slapped on, or perhaps is just cruft left over from the 5.x era?
>>
>> Hrm...
>>
>
> Ike,
>
> 	I'm not sure they ever were really "snappy", but I think you've  
> got two things to content with....

> not any optimization in the code they currently use now to do file  
> backed storage devices *and*

Yes, with GEOM getting all the exiting attention(?)...

> the fact that the size of them has to be much larger than what you  
> used to use back in the 4.x days anyway (I know all my filesystems  
> are definitely much larger than then.....

Ahh- too true.  RAID array size back then was around 80-100gb usable  
space, now the same 1u systems have 850-1400gb.

>
> 	File out who the maintainer of the code is (done by looking in the  
> source for the command), and contact them directly on this issue,  
> they may have some kind of system tuning directly involved with  
> this, either changing block sizes or anything like that in the  
> filesystem creation..... when you get an answer, let us know!
>
> -Trish

Will do- downloading source to grok as I type this...

Rocket-
.ike