[CentOS] using Linux as a NAS / SAN device

oops, pushed replied too soon :)

On Fri, Aug 28, 2009 at 10:07 PM, Les Mikesell<lesmikesell at gmail.com> wrote:
> Rudi Ahlers wrote:
>>
>> The thing is, how will these kind of option perform in a hosting
>> environment where downtime isn't at all an option. We have backup
>> generators, UPS, load balanced networks, etc Even the Tyan /
>> SuperMicro machines that I'm looking at will have redundant power
>> supplies & hard drives.
>>
>> But the one piece of of the puzzle that I don't understand, will a
>> self-build-Linux NAS device, or even Openfiler / FreeNAS give us that
>> kind of uptime.
>
> High quality servers running an enterprise linux version can give you
> the same uptime as dedicated hardware if you are comfortable with not
> doing updates.  For example I still have a RH 7.3 based box running that
> has only been down a few minutes in about 7 years (had to move it) but I
> wouldn't try that with anything exposed to the internet.  I did replace
> several drives and rebuild the raids over that time - and it is probably
> about to die of old age soon.
>
>> The other thing which I would like to also get to, is that we could do
>> more with a Linux based distro than with a off-the-shelf NAS. For
>> example I could setup storage space for users and build custom
>> applications that could manage it all - for example give a hosting
>> client a reseller account with 1TB space and he could resell that to
>> his clients. And I could go as far as setting up SMB / NFS / iSCSI /
>> rsyn / SSH / FTP / sFTP / podcast / HTTP / etc,  i.e. other protocols
>> which a NAS may not necessarily support. And I could even use it as a
>> dedicated web farm if I feel like it, running HTTP & MySQL as well if
>> the server has enough RAM & CPU.
>>
>> Ideally I would like have a highly-redundant storage device which can
>> be used by numerous users, and also host Virtual Machines on it. So IO
>> will be the biggest concern, in terms of speed, with reliability the
>> 2nd biggest concern.
>>
>> I'll run RAID 10 (1+0) for speed & reliability, and use 1TB / 1.5TB
>> RAID edition server grade SATAII hard drives with hardware RAID -
>> although I also think software RAID on a decent CPU could perform
>> better. But the hardware RAID cards have battery backup which gives
>> better reliability. Then I would like to build 2 devices, each syncing
>> with the other one.
>
> The 2 device failover is the tricky part and it introduces some new ways
> to fail.  I've always preferred to keep things simple with mirrored
> disks in a hot-swap chassis so the likely failure (single disk) doesn't
> slow down operation and can be replaced at a convenient time.  The less
> likely motherboard or power supply failure will cause some down time
> while you swap the disks into a spare chassis, though.  And you still
> need off-site backups to cover other types of problems.


For this reason I would be using server grade motherboards, chassis,
drives, etc. All the drive would be hot swappable, and the PSU would
be hot swappable & redundant as well. The only parts that doesn't have
redundancy is the motherboard, CPU, RAM & disk controller.

But, for redundancy I'm thinking of putting together 2 identical
servers which could be setup in active-active sync.

Openfiler offers this out of the box, but it's still a Linux distro,
so I'm looking at giving this a go and see what how it performs.


>
>> The other question is, how well will my own Linux / UNIX based NAS
>> perform? Surely these companies who build their own NAS devices spend
>> a lot of time fine-tuning the OS to deliver the best performance, and
>> probably spend a lot of time researching and testing different
>> hardware devices and configurations to see what works best?
>
> I'd try the canned openfiler/nexentastore installs to see if they meet
> your needs in terms of functionality and performance and if so, then
> decide whether you want to use a supported version or duplicate their
> work setting up something on generic linux/opensolaris.
>
> --
>   Les Mikesell
>    lesmikesell at gmail.com
>
>
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-- 
Kind Regards
Rudi Ahlers
CEO, SoftDux Hosting
Web: http://www.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532