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Re: Advice on system purchase

Martin Steigerwald <Martin@lichtvoll.de> writes:

>> SSDs are a waste of money unless you do have the workload to benefit
>> from them.  And if you have that, where do you store your data?
> I disagree.
> Putting an SSD in this laptop has been the single most effective way to 
> improve all my desktop workloads like it was when I switched from floppy 
> disk to harddisk. Its just insane. This machine is to frigging fast…

Hm what applications or what kind of workload exactly are you talking

> If the CPU isn´t too slow for it and most current CPUs aren´t, a SSD will 
> be highly beneficial for just about any workload that is using random I/O. 
> And most workloads are.

Like?  When you edit a text in an editor or a WYSIWYG word processor or
when you work on a spreadsheet, you are not creating a lot of disk I/O.
When you compress or uncompress a tar archive, you are CPU limited. When
you use a web browser, you are limited by the bandwidth of your network
connection and by CPU --- not to mention your graphics card. When you
play a game, you are limited by graphics card and CPU and perhaps by
memory bandwidth.  When you do photo editing in gimp, you're limited by
CPU and perhaps memory bandwidth and your graphics card, and you my be
limited by having to swap.

Loading the editor or word processor or spreadsheet, tar and bzip2, the
web browser and the game will probably be faster unless they are already
in the disk cache.  Swapping will probably be faster as well.

I just tried with a stop watch: It takes 3 seconds to start libreoffice,
and I have slow disks.  What does it matter if it takes only 1.5 or 2
seconds when you have an SSD instead?

> Thus I would go rather with some dual core i5 + SSD than with a quadcore 
> i7 + harddisk. Save a few bucks on the CPU if you can afford a good SSD 
> then.

I'd rather go with the quadcore.

> And where to store that data? On the SSD.

How much does it cost to make a 4TB RAID-5 and a 500GB RAID-1 with SSDs,
plus having the capacity for backups?  What would be the advantage?

And I'm going to need some more disk space when trying out other
distributions and maybe even windoze in the process of getting rid of

> That said if you just have a media center playing back music or video 
> files the benefits of a SSD would likely only be faster hibernation/resume 
> times.

Sleep and hibernation don't work, I tried that.  I'd really like to have
that working, though.  Perhaps it does with windoze.

If you're stuck with a laptop and don't need to store data on it, I can
see how you prefer SSDs.

> So granted, for workloads, that access big files sequentially an SSD does 
> not make much sense. But in the desktop area thats mainly multimedia stuff 

Yes, I guess if you run things like squid with a big cache on a RAID
built from like 16 SSDs serving a large number of users, you might
benefit from using the SSDs instead of fast SAS disks.  It might even be
cheaper to use the SSDs.  If you do that, you might run into CPU limits
or other limits, though.

> Anyway, in desktops and partly in laptops as well you can combine them. 
> Put random I/O data like OS, applications, mails and other small files on 
> SSD and have a harddisk for photos, music, videos and so on. Thus you get 
> the best of both worlds.

For the money I'd have to pay for the SSDs, I'm better off buying 2TB or
3TB hard drives and just attach them to the RAID.  I don't store data on
a single disk anymore since a long time because I've seen too many disks
failing, so keep in mind that when you talk about "a disk", it is always
at least two of them.

When my system disks fail, I'll go look on ebay and try to get something
like two or three ~320GB disks for about EUR 25 each, or whatever is
available in reasonable size and price.  SSDs can't compete with that,
other than being --- for every day usage insignificantly --- faster.

> Hopefully soon BTRFS will be able to use SSD as cache with the new VFS hot 
> data tracking feature and then you would not have to distribute data 
> manually between SSD and harddisk anymore.

I think my RAID controller can do something like that maybe.  Since SSDs
wear out the faster the more you write to them, I'm not so sure what the
real benefit of such a setup is unless you don't care about the money
--- or have a workload for which it does matter.

Debian testing iad96 brokenarch

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