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Old 06-29-2008, 10:26 PM
Rainer Duffner
 
Default settings up cheap a NAS / SAN server, is it possible?

Am 29.06.2008 um 21:07 schrieb Sorin Srbu:


-----Original Message-----
Actually, the calculation is that it needs a GB of RAM for every
TB of

managed data.

How do you reckon this? Ie, what's the basic assumption(s) for the
statement?

Parity calculations for stripes or what? I don't follow.

I can't say I've ever heard any such like, so please do enlighten me!




It used to be written in the solarisinternals.com wiki - but I can't
seem to find it anymore.


ZFS is a moving target, in some ways, so the requirements may have
changed or are no longer that simple.


But it made sense in the early days, when SUN's thumper (X4500, 2*DC
Opteron, 48 disks, 16 GB RAM) more or less fit the requirements
perfectly.



cheers,
Rainer
--
Rainer Duffner
CISSP, LPI, MCSE
rainer@ultra-secure.de


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Old 06-30-2008, 05:17 AM
Guy Boisvert
 
Default settings up cheap a NAS / SAN server, is it possible?

Les Mikesell wrote:


Are you pricing the low end NAS boxes (like Buffalo
Linkstation/Terastation, etc.)? It might be hard to beat that if all
you want is a file server. Most run Linux of some sort on ARM or PPC
processors and may need to be hacked to add NFS or support >2gig files.






I had an Infrant ReadyNAS NV+ last year (Now Netgear) which was supposed
to be one of the fastest on the market (Cost about 800$ without drives).
A cheaper home made NAS beated it hands down (Software RAID 5). See
last paragraph of:


http://lists.centos.org/pipermail/centos/2008-April/097623.html

The ReadyNAS was a cool little NAS with many services but i found it
slow and choppy. It was a nice little case and the homebrew NAS was
bigger indeed. But the homebrew has power to spare and can do much
more. The ReadyNAS was supposed to get shell access but never made it
before i sold it (WEB Manager only when i had it).



Guy Boisvert, ing.
IngTegration inc.
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Old 06-30-2008, 09:02 AM
"Sorin Srbu"
 
Default settings up cheap a NAS / SAN server, is it possible?

>-----Original Message-----
>>> A cheap server: there are many different values of cheap; it all depends
>>> on what you need it for.
>>>
>>
>> Yupp, break down the requirements into the following three options:
>>
>> * Good
>> * Fast
>> * Cheap
>>
>> Pick any *two*. You can never ever have all three. It's a natural law or
>> something. 8-)
>>
>Sure, SATA isn't as fast as SCSI, so I sacrifice that, but SCSI won't
>give me the same space (3TB) as SATA either. So, a gigabyte mobo + 6x
>1TB SATA HDD's + 4GB RAM + 2.8Ghz Core 2 Duo isn't too bad?

I think your requirements above fall in under "cheap" and "fast". Good in this
case is rather subjective, as SCSI is normally what you want for this kind of
storage.

At work I initially started out with raided scsi-drives for backups and
file-servers whenever I could, but I've lately gone almost completely over to
SATA2-drives with NCQ-features. I get almost the same performance, at a better
price and the MTBF is normally quite good if you chose the right drive-brands.
This too is fast and cheap, although with some caveats visavi longevity. I
think however as long as you have some kind of backup-plan, this isn't really
an issue. With that said, I'd also like to mention we don't do tape-backups
any more. The data-mass is just to much. We use only online-backuping to hd
and rotate the used space as necessary.

What were you going to use this storage server for again? Some kind of
user-homefolder area, backup or such like?

On a different note, our users at the dept' have available a Windows Server
for their homefolder-space. I run this on a low-end Fujitsu-Siemens Primergy
Econel 100-server, with 3x 500GB SATA2/320-drives in Raid0-fashion. The 3x
drives were actually more expensive than the whole server when I bought it
some two years ago. The CPU is a Pentium D at 2,8GHz and has 2GB RAM IIRC. The
price total for this solution was very competitive for us at the time in
Sweden, so you might maybe want to look into the Fujitsu-range low-end
server-line as well.

The Econel-series are as I understand it a sort of hefty
workstation-on-steroids with some server-features included, you kinda' get a
server-workstation hybrid. Look into it and compare prices, you might find
something there.

IMHO, the Econel is the best Good/Cheap/Fast-combo you're likely to find.

HTH.
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Old 06-30-2008, 09:06 AM
"Sorin Srbu"
 
Default settings up cheap a NAS / SAN server, is it possible?

>-----Original Message-----
>From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf
Of
>Rainer Duffner
>Sent: Monday, June 30, 2008 12:27 AM
>To: CentOS mailing list
>Subject: Re: [CentOS] settings up cheap a NAS / SAN server, is it possible?
>
>>>> Actually, the calculation is that it needs a GB of RAM for every
>>>> TB of
>> managed data.
>>
>> How do you reckon this? Ie, what's the basic assumption(s) for the
>> statement?
>> Parity calculations for stripes or what? I don't follow.
>>
>> I can't say I've ever heard any such like, so please do enlighten me!
>>
>
>
>It used to be written in the solarisinternals.com wiki - but I can't
>seem to find it anymore.
>
>ZFS is a moving target, in some ways, so the requirements may have
>changed or are no longer that simple.
>
>But it made sense in the early days, when SUN's thumper (X4500, 2*DC
>Opteron, 48 disks, 16 GB RAM) more or less fit the requirements
>perfectly.

Gotcha', thx!

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Old 06-30-2008, 05:06 PM
David Mackintosh
 
Default settings up cheap a NAS / SAN server, is it possible?

On Sun, Jun 29, 2008 at 09:08:15AM +0200, Rudi Ahlers wrote:
> Hi all
>
> I want to look at setting up a simple / cheap SAN / NAS server using
> normal PIV motherboard, 2GB (or even more) RAM, Core 2 Duo CPU (probably
> a Intel 6700 / 6750 / 6800) & some SATA HDD's (4 or 6x 320GB - 750GB).
> My budget is limited, so I can't afford a pre-built NAS device.

My own experience: I have done two NAS systems using CentOS. One is
a HP DL585G1 with four 300GB drives using a hardware RAID-5. The
second is a Dell PowerEdge 2600 with four 300GB drives (software
raid-10) and two 32GB drives (software raid-1).

One has a multi-core Opteron processor, the other has a high-end
Xeon processor with HT disabled. Both have 2GB of RAM.

Both are used by high-demand compute processes as NFS servers.

Despite a lot of fidding, configuring, testing and tuning, neither
result is very good when it comes to NFS performance. We've gone
so far as to run everything as noatime (ie local mount, nfs export,
and nfs client mount) hoping for better performance.

In comparing the systems we tried the hardware-RAID5 first on the
assumption that HW-Raid5 is faster than SW-Raid, for a higher yield
than Raid-10. However we don't think that the elevator used in the
kernel makes intelligent stepping decisions on the HW-Raid5 because
it doesn't see the "real" geometry of the disks involved, only the
aparrent geometry of the RAID5 disk.

The Software-Raid10 is better in some ways because the kernel sees
the real disk geometries. Performance is about on par with the
other computer, even though the other computer has the better CPU.

Due to the hardware involved I couldn't try Solaris 10, but we have
had experiences in the past where the NFS server on Solaris was
significantly better than the NFS server in CentOS/RedHat, both in
terms of throughput and perceved latency under load.

If I was doing it again, I'd push harder for a budget for a NetApp
filer. For what we are attempting to do, you get what you pay for.

If I was doing it again with the budget restrictions, I'd probably
try Solaris with software raid. I would then try the *BSD family,
but only after Solaris because I have extensive Solaris experience.

--
/oo/
/ /() David Mackintosh |
dave@xdroop.com | http://www.xdroop.com
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Old 06-30-2008, 05:28 PM
"Ross S. W. Walker"
 
Default settings up cheap a NAS / SAN server, is it possible?

David Mackintosh wrote:

> On Sun, Jun 29, 2008 at 09:08:15AM +0200, Rudi Ahlers wrote:
> > Hi all
> >
> > I want to look at setting up a simple / cheap SAN / NAS server using
> > normal PIV motherboard, 2GB (or even more) RAM, Core 2 Duo CPU (probably
> > a Intel 6700 / 6750 / 6800) & some SATA HDD's (4 or 6x 320GB - 750GB).
> > My budget is limited, so I can't afford a pre-built NAS device.
>
> My own experience: I have done two NAS systems using CentOS. One is
> a HP DL585G1 with four 300GB drives using a hardware RAID-5. The
> second is a Dell PowerEdge 2600 with four 300GB drives (software
> raid-10) and two 32GB drives (software raid-1).
>
> One has a multi-core Opteron processor, the other has a high-end
> Xeon processor with HT disabled. Both have 2GB of RAM.
>
> Both are used by high-demand compute processes as NFS servers.
>
> Despite a lot of fidding, configuring, testing and tuning, neither
> result is very good when it comes to NFS performance. We've gone
> so far as to run everything as noatime (ie local mount, nfs export,
> and nfs client mount) hoping for better performance.
>
> In comparing the systems we tried the hardware-RAID5 first on the
> assumption that HW-Raid5 is faster than SW-Raid, for a higher yield
> than Raid-10. However we don't think that the elevator used in the
> kernel makes intelligent stepping decisions on the HW-Raid5 because
> it doesn't see the "real" geometry of the disks involved, only the
> aparrent geometry of the RAID5 disk.
>
> The Software-Raid10 is better in some ways because the kernel sees
> the real disk geometries. Performance is about on par with the
> other computer, even though the other computer has the better CPU.
>
> Due to the hardware involved I couldn't try Solaris 10, but we have
> had experiences in the past where the NFS server on Solaris was
> significantly better than the NFS server in CentOS/RedHat, both in
> terms of throughput and perceved latency under load.
>
> If I was doing it again, I'd push harder for a budget for a NetApp
> filer. For what we are attempting to do, you get what you pay for.
>
> If I was doing it again with the budget restrictions, I'd probably
> try Solaris with software raid. I would then try the *BSD family,
> but only after Solaris because I have extensive Solaris experience.

On Linux storage servers that use RAID try elevator=deadline for
better io scheduling performance.

The default 'cfq' scheduler is really designed for single-disk
interactive workstation io patterns.

-Ross

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Old 06-30-2008, 07:08 PM
Les Mikesell
 
Default settings up cheap a NAS / SAN server, is it possible?

David Mackintosh wrote:


Despite a lot of fidding, configuring, testing and tuning, neither
result is very good when it comes to NFS performance. We've gone
so far as to run everything as noatime (ie local mount, nfs export,
and nfs client mount) hoping for better performance.


Have you updated to Centos 5.2 yet? And if so, did it improve NFS
performance?



--
Les Mikesell
lesmikesell@gmail.com
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Old 07-01-2008, 02:07 AM
David Mackintosh
 
Default settings up cheap a NAS / SAN server, is it possible?

On Mon, Jun 30, 2008 at 02:08:33PM -0500, Les Mikesell wrote:
> Have you updated to Centos 5.2 yet? And if so, did it improve NFS
> performance?

Sorry, these computers are in production now so I can't fiddle with them.

Besides, this would be a "long" upgrade -- they are both CentOS 4.x systems.

--
/oo/
/ /() David Mackintosh |
dave@xdroop.com | http://www.xdroop.com
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Old 07-01-2008, 04:51 AM
Rudi Ahlers
 
Default settings up cheap a NAS / SAN server, is it possible?

David Mackintosh wrote:

On Mon, Jun 30, 2008 at 02:08:33PM -0500, Les Mikesell wrote:

Have you updated to Centos 5.2 yet? And if so, did it improve NFS
performance?



Sorry, these computers are in production now so I can't fiddle with them.

Besides, this would be a "long" upgrade -- they are both CentOS 4.x systems.


------------------------------------------------------------------------


_______________________________________________

This raises an interesting question. What do you do in this kind of
scenario? How do you upgrade a NAS / SAN with say 5 / 10 TB worth of data?


--

Kind Regards
Rudi Ahlers
CEO, SoftDux

Web: http://www.SoftDux.com
Check out my technical blog, http://blog.softdux.com for Linux or other technical stuff, or visit http://www.WebHostingTalk.co.za for Web Hosting stuff

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Old 07-01-2008, 05:12 AM
"nate"
 
Default settings up cheap a NAS / SAN server, is it possible?

Rudi Ahlers wrote:

> This raises an interesting question. What do you do in this kind of
> scenario? How do you upgrade a NAS / SAN with say 5 / 10 TB worth of data?

Lots of the more modern enterprise arrays support online upgrades.
Some of them even support re-distributing data across the new spindles
to maximize performance/limit hot spots.

I personally wouldn't want to purchase any storage array that will
have important data on it that doesn't have these abilities.

My favorite storage company - 3par has some of the more advanced online
optimizations, sample -

http://www.3par.com/documents/3PAR-do-ds-08.0.pdf

Grow data online, convert between RAID levels online, migrate data
between spindle types(FC<->SATA) online etc. Create a volume, and
you never have to worry about answering the question 'is it really
optimal?' because you can change it at any time without application
impact or downtime.

nate

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