samba - Feb 2005 - Building two redundant servers without clustering

Hi,
my Fileserver lately refused to work anymore. I'm quite thankfull for 
that for that it was a bit slow anyway ;-)
My idea is to set up two relativley samba-hosts instead of byuing one 
"real" server with many build in redundancies. That can only work if I
can manage to keep both filesystems in sync and I see two alternatives:
1.: Use drdb to build a RAID1 across the two host's filesystems. If  one 
host fails, the RAID runs in degraded mode but it runs - or does it 
crawl anyway because drdb is slow?
2.:  Use rsync. If I remember correctly, rsync was not supposed to run 
permanently as a daemon to keep two filesystems in sync(?). I could live 
with that, but how big is the overhead if I ran rsync every 5 or 10 minutes?

I want to achieve a trouble free passive fallover. I one host fails, 
people might have to login again and they even might have to wait up to 
30 minutes but then it has to work and they have to get all their files.

This is a public school and data is not worth real money most of the 
time, but once in year there are final exams written and if the server 
breaks down the whole exam has to be redesigned - that could bring me 
into the news.

Does anybody know of any better alternatives I didn't think of?

Thanks a lot,
Malte M?ller
BBS1 Emden

P.S.: My current plans for hardware are two servers, each made up of:
ASUS A8N-SLI plus 2 SATA (WD or Seagate) drives as RAID0 or JBOD.

> Thanks a lot,
> Malte M?ller
> BBS1 Emden
>
> P.S.: My current plans for hardware are two servers, each made up of:
> ASUS A8N-SLI plus 2 SATA (WD or Seagate) drives as RAID0 or JBOD.
SATA sucks. choose SCSI.

anyway You are going to pay more for hardware, so why to choose SATA ?
> -- 
> To unsubscribe from this list go to the following URL and read the
> instructions:  https://lists.samba.org/mailman/listinfo/samba
>

Ilia Chipitsine schrieb:
>> Thanks a lot,
>> Malte M?ller
>> BBS1 Emden
>>
>> P.S.: My current plans for hardware are two servers, each made up of:
>> ASUS A8N-SLI plus 2 SATA (WD or Seagate) drives as RAID0 or JBOD.
>
>
> SATA sucks. choose SCSI.
>
> anyway You are going to pay more for hardware, so why to choose SATA ?
Why should SATA suck? Several comanies build RAIDs with ATA or SATA 
drives (e.g. Transtec). Anyway, I get three years warranty and some 
drives are said to hold that promise. A full fledged server with 
redundant power-supplies and RAID-5 SCSI costs more than 2.5k Euro. A 
cheap one less than 1k. With PCIe it should be possible to get the 
necessary I/O bandwidth.

Thanks for your comment,
Malte M?ller
>
>> -- 
>> To unsubscribe from this list go to the following URL and read the
>> instructions:  https://lists.samba.org/mailman/listinfo/samba
>>
>
>

Thanks a lot Charles. I will try to follow that route.

Malte Mueller

Charles Zealey schrieb:
> WE've gone the drdb route with similar requirements to yours.  Works 
> fine.
>
> Also we've set up heartbeat to do auto failover although not strictly 
> part of the requirement.
> Charles
>
> M. M?ller wrote:
>
>> Hi,
>> my Fileserver lately refused to work anymore. I'm quite thankfull
for
>> that for that it was a bit slow anyway ;-)
>> My idea is to set up two relativley samba-hosts instead of byuing one 
>> "real" server with many build in redundancies. That can only
work if
>> I can manage to keep both filesystems in sync and I see two 
>> alternatives:
>> 1.: Use drdb to build a RAID1 across the two host's filesystems. If
>> one host fails, the RAID runs in degraded mode but it runs - or does 
>> it crawl anyway because drdb is slow?
>> 2.:  Use rsync. If I remember correctly, rsync was not supposed to 
>> run permanently as a daemon to keep two filesystems in sync(?). I 
>> could live with that, but how big is the overhead if I ran rsync 
>> every 5 or 10 minutes?
>>
>> I want to achieve a trouble free passive fallover. I one host fails, 
>> people might have to login again and they even might have to wait up 
>> to 30 minutes but then it has to work and they have to get all their 
>> files.
>>
>> This is a public school and data is not worth real money most of the 
>> time, but once in year there are final exams written and if the 
>> server breaks down the whole exam has to be redesigned - that could 
>> bring me into the news.
>>
>> Does anybody know of any better alternatives I didn't think of?
>>
>> Thanks a lot,
>> Malte M?ller
>> BBS1 Emden
>>
>> P.S.: My current plans for hardware are two servers, each made up of:
>> ASUS A8N-SLI plus 2 SATA (WD or Seagate) drives as RAID0 or JBOD.
>
>

Hi M
> 1.: Use drdb to build a RAID1 across the two host's filesystems. If 
one
> host fails, the RAID runs in degraded mode but it runs - or does it
> crawl anyway because drdb is slow?
[Mitch says:] I've never used this, and a quick google doesn't give me
anything useful - what's the home page?
> 2.:  Use rsync. If I remember correctly, rsync was not supposed to run
> permanently as a daemon to keep two filesystems in sync(?). I could live
> with that, but how big is the overhead if I ran rsync every 5 or 10
> minutes?
[Mitch says:] This is something I've been playing with. Wasn't having
any
problems until the filesets got largish (>40GB) - now I see performance
issues.... one key is to write your sync script with a lock - you don't want
cron starting a second one while the first is still running - at some point,
I'd like to investigate some performance enhancements to rsync - either to
pull a file list from fam or something to eliminate deep traversal of
unmodified dirs (may involve a file system hack).
> I want to achieve a trouble free passive fallover. I one host fails,
> people might have to login again and they even might have to wait up to
> 30 minutes but then it has to work and they have to get all their files.
> 
> This is a public school and data is not worth real money most of the
> time, but once in year there are final exams written and if the server
> breaks down the whole exam has to be redesigned - that could bring me
> into the news.
> 
[Mitch says:] Personally (SCSI bigots aside ;-) I don't have any issues with
SATA drives for a low demand server - sure ultra fast scsi would be quicker,
but a large mirror ALWAYS beats smaller drives in raid 5 or other more
controller dependant setups. There are even a few controllers that do the
raid as a "hardware" sata raid - Adaptec has one - 3ware too I think.
They
have proper recovery tools and so on for FreeBSD and Linuxes I think.

m/