Raid0 or Raid5 for network to disk backup (Gigabit)?

markm75 wrote:

Anyone have any thoughts on which is going to give me better write
speeds.. I know raid0 should be much better and if i combine it with
raid1, redundant..

But I'm assuming when I backup my servers to (this backup server)
across the gigabit network, my write speeds would max out at say 60 MB/
s wouldnt they?

I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..

Any thoughts?


two disk raid0 with write cache turned on. better read/write
performance all around and twice the disk space. run the
backup machine with a UPS power supply

so what if it (raid0) fails every few years? it's a minor backup
machine and odds are that it won't be the end of the world

if the backup is not "minor" (meaning totally critical),
then go with slower raid5 (or something similar)

bill

markm75 wrote:


I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..

Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

In comp.sys.ibm.pc.hardware.storage Maurice Volaski wrote:
markm75 wrote:


I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..

Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

With a reasonable buffer (not cache) implementation, yes. Something
seems wrong or MS screwed up rather badly in implementing this.

But the 75MB/s figure only applies to the start of the disk.
At the end it is typically is somewere in the 35...50MB/s range,
since the cylinders contain less sectors.

Arno

On Mar 29, 5:59 am, Arno Wagner wrote:
In comp.sys.ibm.pc.hardware.storage Maurice Volaski wrote:

markm75 wrote:

I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..
Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

With a reasonable buffer (not cache) implementation, yes. Something
seems wrong or MS screwed up rather badly in implementing this.

But the 75MB/s figure only applies to the start of the disk.
At the end it is typically is somewere in the 35...50MB/s range,
since the cylinders contain less sectors.

Arno

Apologies.. Yeah when bypassing the cache I got an index of 57MB/s...

"markm75" wrote in message oups.com
On Mar 29, 5:59 am, Arno Wagner wrote:
In comp.sys.ibm.pc.hardware.storage Maurice Volaski wrote:

markm75 wrote:

I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..
Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

With a reasonable buffer (not cache) implementation, yes. Something
seems wrong or MS screwed up rather badly in implementing this.

But the 75MB/s figure only applies to the start of the disk.
At the end it is typically is somewere in the 35...50MB/s range,
since the cylinders contain less sectors.

Arno

Apologies.. Yeah when bypassing the cache I got an index of 57MB/s...

No, really?
Who would have thought that from your first post. Thanks for clearing that up.
It all becomes much clearer now.

On Mar 29, 11:29 am, "markm75" wrote:
On Mar 29, 5:59 am, Arno Wagner wrote:





In comp.sys.ibm.pc.hardware.storage Maurice Volaski wrote:

markm75 wrote:

I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..
Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

With a reasonable buffer (not cache) implementation, yes. Something
seems wrong or MS screwed up rather badly in implementing this.

But the 75MB/s figure only applies to the start of the disk.
At the end it is typically is somewere in the 35...50MB/s range,
since the cylinders contain less sectors.

Arno

Apologies.. Yeah when bypassing the cache I got an index of 57MB/s...- Hide quoted text -

- Show quoted text -

If I use the option, checked off, "Bypass windows cache" I do in fact
get HIGHER values than when not bypassing the cache..

I know this sounds reversed, but it is what happens.

In comp.sys.ibm.pc.hardware.storage markm75 wrote:
On Mar 29, 11:29 am, "markm75" wrote:
On Mar 29, 5:59 am, Arno Wagner wrote:





In comp.sys.ibm.pc.hardware.storage Maurice Volaski wrote:

markm75 wrote:

I think right now on Raid5, sataII, i'm getting a write speed of 57 MB/
s (bypassing windows cache, using SIsandra to benchmark).. if you dont
bypass the windows cache this becomes more like 38 MB/s..
Aren't these numbers reversed? Anyway, good drives should be 75
MB/second when the cache is bypassed. Not bypassing it should give
significantly greater performance.

With a reasonable buffer (not cache) implementation, yes. Something
seems wrong or MS screwed up rather badly in implementing this.

But the 75MB/s figure only applies to the start of the disk.
At the end it is typically is somewere in the 35...50MB/s range,
since the cylinders contain less sectors.

Arno

Apologies.. Yeah when bypassing the cache I got an index of 57MB/s...- Hide quoted text -

- Show quoted text -

If I use the option, checked off, "Bypass windows cache" I do in fact
get HIGHER values than when not bypassing the cache..

I know this sounds reversed, but it is what happens.

It is possible. It does however point to some serious problem
in the write-buffer design.

Arno

If I use the option, checked off, "Bypass windows cache" I do in fact
get HIGHER values than when not bypassing the cache..

I know this sounds reversed, but it is what happens.

Depends on data access pattern, on some patterns it is really profitable. For
instance, databases like MSSQLServer also use cache bypass.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation

http://www.storagecraft.com