Matthias Langbein wrote (in part):

> Therefor I wondere wheter an experienced administrator could give me a
> hint, how much RAM I'd need for this? The server is only supposed to
> work as a file server, which means network drives under samba...

I would not call myself an experienced administrator. Other than my own
Linux boxen, I have not had to administer systems since I helped with this
with a battery of UNIX systems running on DEC PDP-11 and VAX-11 machines in
around 1980 or so. And I did not enjoy that very much. Recall that in those
days, to add a new device in the /dev directory, you had to run a debugger
on the directory file and add the entry (name, i-node number, etc.) that way.
>
> Are S-ATA drives good enough, or is the extra cost for SCSI drives
> worth the money??

I do not know. It is going to depend on what you mean by "good enough" and
even then, I believe you are going to have to rely somewhat on your intuition.

* I do not know the top speeds fo S-ATA drives. I know the SCSI drives will
run up to 15,000rpm. Depending on throughput requirements, you may need very
high speed drives (and then again, you may not: only you can tell this). One
way is to examine the performance of your current system to see what
throughput rates your clients demand, determine if you are satisfying the
current demand, make reasonable estimates of requirements for the lifetime
of the new machine, and decide accordingly.

* Depending on usage patterns of the clients, you may want the ability of
SCSI controllers to schedule multiple commands (especially seeks) on
multiple drives concurrently. Perhaps S-ATA controllers can do this just as
well as SCSI controllers (I do not know), but IDE - EIDE - ATA controllers
pretty much do not.

* There is a belief (though I have seen only indications, but no good
statistics) that SCSI hard drives are more reliable than IDE - EIDE - ATA
drives. I do not know if this is true. It is true that the only hard drive I
ever had go bad was an IDE drive, but that is not statistically significant.
I do know that many SCSI drives (perhaps all) come with 5-year warranties
(whatever that proves), and it is rare for IDE drives to come with those.
Maybe the manufacturers know something. I do not know the warranty period
for S-ATA drives, but you should find out.
>
> THX for the help,
> Langi


--
.~. Jean-David Beyer Registered Linux User 85642.
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/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 08:35:00 up 18 days, 19:06, 5 users, load average: 4.18, 4.23, 4.20

On Thu, 15 Dec 2005 08:48:01 -0500, Jean-David Beyer wrote:

>> Are S-ATA drives good enough, or is the extra cost for SCSI drives
>> worth the money??
>
> I do not know. It is going to depend on what you mean by "good enough" and
> even then, I believe you are going to have to rely somewhat on your intuition.
>
> * I do not know the top speeds fo S-ATA drives. I know the SCSI drives will
> run up to 15,000rpm. Depending on throughput requirements, you may need very
> high speed drives (and then again, you may not: only you can tell this).

SCSI is hugely more expensive per storage unit, and vastly superior for
very high throughput uses.

SATA drives are normally identical to the PATA drives of the same spec,
but with different cables.

Are SCSI drives better made? Well, Maxtor, for one, offers a 2-year
warranty on their PATA and SATA drives in Europe. The SCSI drives get
a 5-year warranty. What would you think?

--
mark south: world citizen, net denizen
echo znexfbhgu2000@lnubb.pb.hx|tr a-z n-za-m
"Take it? I can't even parse it!" - Kibo, in ARK

"Mark South" <mark.south@null.invalid> wrote in message
newsan.2005.12.15.20.51.41.429960@bluewin.ch...
> On Thu, 15 Dec 2005 08:48:01 -0500, Jean-David Beyer wrote:
>
>>> Are S-ATA drives good enough, or is the extra cost for SCSI drives
>>> worth the money??
>>
>> I do not know. It is going to depend on what you mean by "good enough"
>> and
>> even then, I believe you are going to have to rely somewhat on your
>> intuition.
>>
>> * I do not know the top speeds fo S-ATA drives. I know the SCSI drives
>> will
>> run up to 15,000rpm. Depending on throughput requirements, you may need
>> very
>> high speed drives (and then again, you may not: only you can tell this).

SATA currently tops out at 10,000 RPM. The resultingly better seek time has
to be balanced off against the fact that memory is much cheaper and caching
much improved, so you don't churn little chunks of data to disk as often as
we used to.

> SCSI is hugely more expensive per storage unit, and vastly superior for
> very high throughput uses.

"It depends". If I can use the same $20,000 and buy 3 times as much storage
and backup for it, and never have to put stuff on tape, that can be a huge
win. If I'm manipulating huge databases where I have no hope of storing it
all in RAM and I have to search disk for complex queries (such as some
indisutrial Oracle setups), SCSI wins hands down.

> SATA drives are normally identical to the PATA drives of the same spec,
> but with different cables.
>
> Are SCSI drives better made? Well, Maxtor, for one, offers a 2-year
> warranty on their PATA and SATA drives in Europe. The SCSI drives get
> a 5-year warranty. What would you think?

Except that with the money I save buying SATA instead of SCSI, I can often
get twice the amount of space, and look at replacing the whole array in 2 or
3 years, decommissioning the old array for less critical uses.

Nico Kadel-Garcia wrote:
> "Mark South" <mark.south@null.invalid> wrote in message
> newsan.2005.12.15.20.51.41.429960@bluewin.ch...
>
>> On Thu, 15 Dec 2005 08:48:01 -0500, Jean-David Beyer wrote:
>>
>>
>>>> Are S-ATA drives good enough, or is the extra cost for SCSI drives
>>>> worth the money??
>>>
>>> I do not know. It is going to depend on what you mean by "good
>>> enough" and even then, I believe you are going to have to rely
>>> somewhat on your intuition.
>>>
>>> * I do not know the top speeds fo S-ATA drives. I know the SCSI
>>> drives will run up to 15,000rpm. Depending on throughput
>>> requirements, you may need very high speed drives (and then again,
>>> you may not: only you can tell this).
>
>
> SATA currently tops out at 10,000 RPM. The resultingly better seek time
> has to be balanced off against the fact that memory is much cheaper and
> caching much improved, so you don't churn little chunks of data to disk
> as often as we used to.
>
How big are the caches in the SATA drives? 8 Megabytes is typical for SCSI
drives these days.
>
>> SCSI is hugely more expensive per storage unit, and vastly superior for
>> very high throughput uses.
>
>
> "It depends". If I can use the same $20,000 and buy 3 times as much
> storage and backup for it, and never have to put stuff on tape, that can
> be a huge win. If I'm manipulating huge databases where I have no hope of
> storing it all in RAM and I have to search disk for complex queries (such
> as some indisutrial Oracle setups), SCSI wins hands down.
>
It depends on whether you need off-premise backups. You would probably
prefer to put some tapes in a safe deposit box (perhaps a large one) at your
bank, where you would never want to put a set of hard drives from your RAID
system there. ;-)
>
>> SATA drives are normally identical to the PATA drives of the same spec,
>> but with different cables.
>>
>> Are SCSI drives better made? Well, Maxtor, for one, offers a 2-year
>> warranty on their PATA and SATA drives in Europe. The SCSI drives get
>> a 5-year warranty. What would you think?
>
>
> Except that with the money I save buying SATA instead of SCSI, I can
> often get twice the amount of space, and look at replacing the whole
> array in 2 or 3 years, decommissioning the old array for less critical
> uses.
>
Yes, but. Remember all these things, after a large failure rate for
congenital weakness at the beginning, seem to follow a bell curve in failure
rates. So I imagine the peak of the bell curve is at 5 years or a bit more
for units with 5-year warranties, and at 2 years or a bit more for units
with 2-year warranties. This does not mean you will not get failures at 4
years and 20 months, with those drives, respectively.

Now are hot-swappable SATA drives significantly cheaper than similar SCSI
drives? I do not happen to know.


--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ PGP-Key: 9A2FC99A Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 08:30:00 up 19 days, 19:01, 6 users, load average: 4.55, 4.35, 4.29

"Jean-David Beyer" <jdbeyer@exit109.com> wrote in message
news:11q5gmdm70kil27@corp.supernews.com...

> Yes, but. Remember all these things, after a large failure rate for
> congenital weakness at the beginning, seem to follow a bell curve in
> failure
> rates. So I imagine the peak of the bell curve is at 5 years or a bit more
> for units with 5-year warranties, and at 2 years or a bit more for units
> with 2-year warranties. This does not mean you will not get failures at 4
> years and 20 months, with those drives, respectively.

Well, yes. But having four year old SCSI drives is often just a burden, when
you can replace them at 2 or 3 years with much larger, less expensive drives
running on a new server that draws less power and cooling. Such things
matter in both home use and industrial scale. And since the most common
cause of file loss is user error, not disk failure (in my experience),
having spare local disk for nightly mirrors is really useful.

> Now are hot-swappable SATA drives significantly cheaper than similar SCSI
> drives? I do not happen to know.

For the same size drive, not much less. But for the same money in SATA, you
can get a *MUCH* larger drive.I can get a decent 300 Gig SATA for $250 off
the shelf. I can get a decent 300 Gig SCSI for about $800 off the shelf.