Re: [BackupPC-users] New backup server
2013-05-24 14:34:07
Erik Hjertén <erik.hjerten AT companion DOT se> wrote
on 05/24/2013 12:15:22 PM:
> Hi all
>
> I have invested in a used HP Proliant ML150 G5 server as a new
> backup server. I have about 500 GB of data in 40 000 files spread
> over 8 clients to backup. Data doesn't grow fast so I'm aiming at
> two 1TB disks in a raid 1 configuration.
>
> Do I go with more expensive, but faster (and more reliable?), SAS-
> disks. Or is cheaper, but slower, S-ATA disks sufficient? I'm
> guessing that disk speed will be the bottle neck in performance?
>
> Your thoughts on this would be appreciated.
What is your backup window? 12 hours? You
could do that with a *single* 7200 RPM SATA drive. 8 hours? Probably
still, but you'd have to do some testing to see. Less than that?
You're going to need to intimately undertand both your circumstances
and the various technologies inside of BackupPC to be able to answer that
better.
Frankly, a mirrored array isn't gonna buy you much
performance increase. It won't help write performance at *all*, and
I'm not sure you'll need enough read performance to matter: the high
amount of seeking that BackupPC requires doesn't really hep for getting
sustained high read performance.
I will take Les' advice (don't use the Green drives)
one step farther: I recommend the drives designed for DVR/Video use.
"Normal" drives (the not-Green drives) are warrantied only
for 8x5 usage; the DVR drives are rated for 24x7 usage. They're
a little more expensive, but not much.
There are other questions you will need to ask that
will make as much (if not more) difference than the speed of the drives
you'll be using:
* Would more drives (even if they're slower) give
you better performance?
* How fast can the *clients* push the data? If
you're limited by them, improving the server won't help?
* What is the speed of the network involved? Are
you talking 100Mb/s or slower? That will severely limit your performance.
Do you Gigabit everywhere between them? Are there points in
between that might cause problems (like if the clients and server are in
*different* switches)? Can you do bonded Ethernet on the server?
* What technique are you using to back up the files?
Rsync over ssh (with encryption overhead)? Rsyncd? tar/SMB
(which are much less intelligent in transferring files, but maybe less
disk-intensive)? Will you use compression on the server, and what
level of CPU do you have?
* What do your files look like? 40,000 files
for 500GB of data is a pretty high size-per-file. (Contrast with
one of my servers, which is 800GB, but 400,000 files: 1/5 the data per
file.) Are your files mostly small (say, under 10kB), mostly average
(10k to 10M)? Do you have any massive files (1GB or larger) to deal
with? Backing up a database server and backing up a mail server require
*noticeably* different approaches.
(Believe it or not, even all of *this* is not all
that's involved!)
Your question is along the lines of "Which is
faster, a bicycle or a dump truck?" The answer is: it
depends. Need to move a mountain of sand 50 miles away? A dump
truck. Delivering urgent letters in Manhattan? Bicycle! :)
I know you tried to give us some idea of what you're trying to do
(500GB and 40,000 files across 8 clients), but not nearly enough to accurately
answer the question.
But keep this in mind: the numbers that you
supplied are what I would consider small and "boring": a
relatively small amount of data and a relatively small number of clients.
The only thing I find interesting is that your 500GB of data is only
40,000 files. That's a small number of files, so I am curios as to
the size of your files. Other than that small eybrow-raising item,
your application is extremely straightforward--assuming that the answer
to all of the questions above are the typical answers I would expect in
a decent office environment.
Tim Massey
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