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From: Sharon F on 6 Mar 2010 14:15
David Empson <dempson(a)actrix.gen.nz> wrote:

> Dan <me(a)here.net> wrote:
>
> > In article <1jeuscz.1ghd4sndm9n5fN%dempson(a)actrix.gen.nz>,
> > dempson(a)actrix.gen.nz (David Empson) wrote:
> >
> > > A large chunk of the saving is due to using a compression mechanism for
> > > many files in the system.
> >
> > Does this result in a performance hit, by needing to decompress files on
> > every access?
>
> Not a significant one.
>
> Do a Google search for "HFS+ File Compression" to find some background.
> It was described in detail in an Ars Technica review of Snow Leopard,
> and the relevant bit is duplicated here:
>
> <http://blog.fosketts.net/2009/09/11/bizarre-hfs-tricks-in-mac-os-x-10-6
> -snow-leopard/>
>
> In short, the compression is only used for read-only system files, and
> the files in question are likely to be read infrequently (e.g. when
> loading an application or library), so the impact is relatively low.
>
> The CPU is fast enough that it probably takes less time to decompress
> the data than it would to read a larger file from the hard drive. Net
> result is more CPU activity and probably neutral for time required to
> load the file, but a significant space saving.
>
> If the computer has a solid state disk instead of a hard disk, the
> compression may be a performance disadvantage, but the space saving is
> even more important because of relatively small capacities for solid
> state disks.


Why is compression considered a performance disadvantage for solid state
drives?

--
Sharon F
From: Sharon F on 6 Mar 2010 14:31
Sharon F <sharonf(a)mvps.org.invalid> wrote:

> David Empson <dempson(a)actrix.gen.nz> wrote:
<snippage>
> >
> > If the computer has a solid state disk instead of a hard disk, the
> > compression may be a performance disadvantage, but the space saving is
> > even more important because of relatively small capacities for solid
> > state disks.
>
>
> Why is compression considered a performance disadvantage for solid state
> drives?

Never mind. Did some googling and read several articles on SSD
technology. If anyone else is interested, this Anandtech article was a
good all round read:

<http://www.anandtech.com/storage/showdoc.aspx?i=3531&p=1>

--
Sharon F
From: Sharon F on 6 Mar 2010 14:43
Sharon F <sharonf(a)mvps.org.invalid> wrote:

> Sharon F <sharonf(a)mvps.org.invalid> wrote:
>
> > David Empson <dempson(a)actrix.gen.nz> wrote:
> <snippage>
> > >
> > > If the computer has a solid state disk instead of a hard disk, the
> > > compression may be a performance disadvantage, but the space saving is
> > > even more important because of relatively small capacities for solid
> > > state disks.
> >
> >
> > Why is compression considered a performance disadvantage for solid state
> > drives?
>
> Never mind. Did some googling and read several articles on SSD
> technology. If anyone else is interested, this Anandtech article was a
> good all round read:
>
> <http://www.anandtech.com/storage/showdoc.aspx?i=3531&p=1>

PS: Dave's right about system files not being a large impact on
performance. (Should have acknowledged that in my last post but am
suffering from a 24 hour flu and not thinking very clearly. Please
excuse!) Other operating systems do this with system files as well -
well, Windows at least. Until reading I wasn't aware that there was any
more of an impact for SSD vs spinning hard drives. Googled "compression
on solid state drives"

--
Sharon F
From: Geico Caveman on 8 Mar 2010 12:42
On 2010-02-26 13:52:58 -0700, Robert Peirce <bob(a)peirce-family.com> said:

> I am still on 10.4. My wife is on 10.5. I held off on upgrading
> because I kept hearing stories about various driver problems. I haven't
> been hearing those lately. Are we all clear at this point?

Safari has been acting very slow (I have tried repairing permissions).
I switched from Firefox to Safari because it was faster. Its painful
now.

My Leopard machine at work has no such issues.

Second - if you join a lot of PDFs, Preview has changed a bit in Snow
Leopard. Earlier, you could just drag the PDFs to the sidebar, select
all and save as. Now you have use print to pdf.

There are driver issues. NI-VISA does not stable drivers for Snow
Leopard. Comsol does not install without a special patch. There are
others I have heard of, but not experienced myself.

I upgraded as soon as Snow Leopard came out. I have been mostly happy
with it, but if I had to do this again, I would wait until 10.6.3 or 4
came out. Too many rough edges initially - its the nature of the
software development process.

From: Jolly Roger on 8 Mar 2010 14:16
In article <2010030810423950073-spammersgohere(a)spaminvalid>,
Geico Caveman <spammers-go-here(a)spam.invalid> wrote:

> On 2010-02-26 13:52:58 -0700, Robert Peirce <bob(a)peirce-family.com> said:
>
> > I am still on 10.4. My wife is on 10.5. I held off on upgrading
> > because I kept hearing stories about various driver problems. I haven't
> > been hearing those lately. Are we all clear at this point?
>
> Safari has been acting very slow (I have tried repairing permissions).
> I switched from Firefox to Safari because it was faster. Its painful
> now.
>
> My Leopard machine at work has no such issues.

Then again, Safari is speedy and mostly problem-free for most 10.6
users, including me, on multiple model Macs.

Sounds like you should do some work to diagnose the issue and correct
it. I would start by examining the /var/log/system.log for error
messages related to Safari. Then I would look at the console log for
similar messages. If any messages are found, they may give a clue as to
what is causing the issue. Next, I would try running Safari from a
brand-new Mac OS X user account to see if the problem is local to your
user account. Next, I would probably try the Reset Safari command. Etc.
And so on...

> There are driver issues. NI-VISA does not stable drivers for Snow
> Leopard. Comsol does not install without a special patch. There are
> others I have heard of, but not experienced myself.

Yep. Lots of drivers need to be updated for 10.6 compatibility. But then
this was true for 10.4 as well.

> I upgraded as soon as Snow Leopard came out. I have been mostly happy
> with it, but if I had to do this again, I would wait until 10.6.3 or 4
> came out. Too many rough edges initially - its the nature of the
> software development process.

Good idea. I usually wait at least a couple weeks, to see what problem
reports trickle in on the net, before considering whether or not I will
upgrade right away or wait a while for a patch or two to be released. In
the case of 10.6, I waited until 10.6.1 was released, and was happy to
upgrade after that.

--
Send responses to the relevant news group rather than email to me.
E-mail sent to this address may be devoured by my very hungry SPAM
filter. Due to Google's refusal to prevent spammers from posting
messages through their servers, I often ignore posts from Google
Groups. Use a real news client if you want me to see your posts.

JR
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