[mythtv-users] USB Flash Memory for boot/system. What is fast enough?

Brian Wood beww at beww.org
Mon Nov 23 16:28:39 UTC 2009

On Monday 23 November 2009 09:09:47 Greg Cope wrote:

> I would argue that for an FE you should only tun things for playback
> implying that they should not be swapped out.
> However I see no technical reason why you could npt have swap on
> flash, and with it's low seek tume flash is actually quite suited to
> it.  Windows ready boost is using it in this way (ie extending VM).

The only problem I see is if you are making very heavy use of swap it might 
wear out the flash device, but if you are swapping that much you need more 
RAM anyway.

> > I'm not sure what the noatime parameter would do with a swap
> > partition, it's
> > intended to eliminate writing the access time each time a file is
> > accessed on
> > a normal file system, but swap is not handled as a normal filesystem.
> Noatime will do nothing for swap.

That's what I suspected, thanks for confirming it. I'm surprised the system 
even accepts that parameter for a swap partition.
> > If it's not causing any problems it certainly couldn't hurt, but I
> > would try
> > to get swap off a flash device, either by eliminating it entirely if
> > you can,
> > or writing it to a standard HDD partition, or even use an NFS-
> > mounted file.
> >
> > Swap can be enabled on either a partition or a file, as you probably
> > know.
> >
> > Perhaps someone with a better understanding of how the kernel
> > handles swap
> > will have better suggestions?
> >
> > --
> You can trun down swappyness or run with none at all as long as you
> have enough memory to run all the bits you need.  Otherwise when the
> kernel gets desperate it will run an OOM killer that usually zaps
> something important.  Memory is pretty cheap.
> Netbooting is usually easy to configure and update.  Once running in a
> ram disk things are usually pretty fast.  You then avoid any USB
> storage issues and the CPU overhead of USB storage (Scsi emulation
> etc...)
> Having said that if you are not going to run nfs and or this is for a
> backend flash can be ok as long as you get a reliable stick.  If
> anyone has any recomendations bar the patriot xts pls share!

That's why I get frustrated when they supply such minimal specs for the 
devices. Some have better wear-leveling algotithms than others, but I guess 
you can't expect a vendor to advertise "crappy wear leveling". 

Sometimes different devices with identical capacity have vastly different 
prices, but I never know if a higher price indicates a better device or a 
greedier vendor.

Brian Wood
beww at beww.org

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