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Re: amanda dumps on Sun E250
2008-03-18 18:35:58
I'm going to cut sections out of the exchange in order to focus. Anyone
coming in late should look back on the thread. -- Chris H.
Brian Cuttler wrote:
On Tue, Mar 18, 2008 at 04:32:53PM -0400, Chris Hoogendyk wrote:
<snip>
I believe your speed to tape is less than mine. It looks like you are up
over 500G being backed up. If I plugged that into my tape speed, I would
be doing it in about 10 hours. Of course, that assumes other factors
aren't bottlenecking, which you say they aren't. And your tapes should
be faster.
Well, I'm getting data to the holding areas faster than I'm clearing
them, so I think I can eliminate the other issues. It looked like
simple logic to me, which usually means I've overlooked something.
So, where to from there? I have two 300G ultraSCSI/320 10k-rpm Seagate
Cheetah holding drives. They are mounted internally. I have a PCI
Ultra320 dual SCSI expansion card that I added to the E250. The tape
library is connected through that. I bought it through our authorized
Sun reseller, and it's a Sun branded card.
My amanda work areas are all in a multipack connected to a Sun branded
HBA. Similarly the connection to the tapes, either the original ext bus
or an approved HBA (I have to look).
<snip>
At the moment, we are running 100Mb/s ethernet using the onboard
connector (hme0). We are about to switch to GigE using PCI cards that we
bought from the same reseller. They are also Sun branded cards. In
discussing with their engineer how to configure this, we decided that we
would keep the Ultra320 SCSI card in PCI slot 3, which is 66MHz, and put
the GigE card (single) into one of the other slots, which are 33MHz.
<snip>
I disabled compression back when each of the two Lotus notes servers
was an E250 and each ran their own amanda server and had only themselves
as a client. We moved to HW compression at that time. We are still
running HW compression now.
<snip>
Beyond possible tuning issues, I believe amanda actually uses # DD
to move the data to tape. While I do want to upgrade amanda, and I
would do so tomorrow if someone said it was causing any sort of
performance issue, I don't know if that is the place to look.
yup. Amanda uses dd. I doubt upgrading would solve the problem.
<snip>
I'm stuck with hand-me-down E250's, because I can't get either
department to squeeze any money out of their budget for upgrades. While
I think a newer server would handle some things faster, I also think the
E250 ought to be able to drive the tape faster than you are experiencing.
I thought it would also, I just need to find out what to push on to
improve the situation.
Here are the amdump results.
This is from the once/week run - where we expect level 0 for
all partitions, I would expect at least 10x the I/O rate to
the LTO drive.
<snip>
Tape Time (hrs:min) 39:44 39:44 0:00
Tape Size (meg) 556921.9 556921.9 0.0
Tape Used (%) 278.5 278.5 0.0
Filesystems Taped 18 18 0
Avg Tp Write Rate (k/s) 3986.3 3986.3 --
USAGE BY TAPE:
Label Time Size % Nb
NOTESX29 15:51 87296.7 43.7 10
NOTESX30 3:40 130923.7 65.5 2
NOTESX31 8:56 127639.2 63.8 3
NOTESX32 7:26 103730.4 51.9 2
NOTESX33 3:52 107332.0 53.7 1
<snip>
These are the results from the LTO3 drive, dumps performed 5x/week.
I'd hope for way more performance from this drive.
<snip>
Tape Time (hrs:min) 39:37 4:09 35:28
Tape Size (meg) 514464.9 118889.8 395575.1
Tape Used (%) 133.3 30.8 102.5 (level:#disks ...)
Filesystems Taped 18 3 15 (1:15)
Avg Tp Write Rate (k/s) 3693.4 8140.4 3172.5
USAGE BY TAPE:
Label Time Size % Nb
NOTES11 36:08 459823.1 119.1 17
NOTES12 3:29 54641.9 14.2 1
<snip>
Interesting that your LTO3 is doing no better than your LTO for speed. I
would guess you should be getting 3 times the speed you are getting on
LTO and well over 10 times the speed you are getting on LTO3.
Also, doing hardware compression, I would expect you to get more than
you are on tape unless the data is relatively uncompressable. If Lotus
keeps its stuff in compressed form, you could be running into slowdowns
on the hardware compression.
With the speeds you are getting, I would be worried about shoe shining.
Can you actually watch the tapes while they are running and see what's
happening? That will take a slow speed and make it dismal, which is what
you have. My AIT5 on my E250 is beating out your LTO3, and it shouldn't.
You should be 2-3 times faster.
If any of that makes sense to you, and since you don't seem to be
gaining much from compression, I'd be inclined to turn off compression
altogether and see what happens. Of course, that can be a bit tricky
with tapes that have already been used with compression. I think I saw a
discussion somewhere about someone turning backflips to accomplish that.
Might have been on the bacula list. Tape drives and OS level stuff
translate almost completely between the two lists.
If you can ever get any down time, I would be inclined to take one of
the large notes partitions, recover it to the holding disk, and then
play with dd'ing it to the tape until you figure out what's up.
If you use the standard SCSI port on the back of the E250, it is
UltraSCSI, but only the earliest version. It can only do 40MB/s. It also
supports single ended, wide or narrow SCSI devices. So, if there are
other things also connected, and you are using that connection, then you
probably have a problem with LTO3 from that perspective. I would double
check and make sure you have connections and adapters that will support
the throughput you need. I presume you have the E250 Server Owner's Guide?
Good luck (intended positively ;-) ).
---------------
Chris Hoogendyk
-
O__ ---- Systems Administrator
c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst
<hoogendyk AT bio.umass DOT edu>
---------------
Erdös 4
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