Amanda-Users

Re: Slow dumper

2003-04-07 07:38:04
Subject: Re: Slow dumper
From: Bartho Saaiman <bartho AT cae.co DOT za>
To: Paul Bijnens <paul.bijnens AT xplanation DOT com>
Date: Mon, 07 Apr 2003 11:35:13 +0200
Hi Guys.

Don't know how this came up again as I have resolved the issue a while ago. I am not going to trim the message as some other persons might gain something from this.

I replaced the server in question with a new one using only SCSI disk. Previous setup used IDE (not by choice) and was also using software RAID 5. System is now running on SCSI config with hardware RAID 5 and is dumping to a seperate disk. Huge improvement and this is what I am getting now. One thing I can recommend is that if you have some money to spend on hardware, by the best you can afford. My backups are now completing 3 times as fast as previously and that is a benefit in itself.

STATISTICS:
                          Total       Full      Daily
                        --------   --------   --------
Estimate Time (hrs:min)    0:01
Run Time (hrs:min)         3:51
Dump Time (hrs:min)        3:22       3:22       0:00
Output Size (meg)       15600.6    15600.6        0.0
Original Size (meg)     23192.5    23192.5        0.0
Avg Compressed Size (%)    65.5       65.5        --
Filesystems Dumped           11         11          0
Avg Dump Rate (k/s)      1315.0     1315.0        --

Tape Time (hrs:min)        1:48       1:48       0:00
Tape Size (meg)         15601.0    15601.0        0.0
Tape Used (%)              78.0       78.0        0.0
Filesystems Taped            11         11          0
Avg Tp Write Rate (k/s)  2459.9     2459.9        --

Paul Bijnens wrote:

On Tue May 28 2002 05:09, Bartho Saaiman wrote:

I have a problem where my dumper is slow and the taper seems to be
faster:

STATISTICS:
                         Total       Full      Daily
                       --------   --------   --------
Estimate Time (hrs:min)    0:02
Run Time (hrs:min)        11:21
Dump Time (hrs:min)        9:42       9:42       0:00
Output Size (meg)       14818.3    14818.3        0.0
Original Size (meg)     20804.7    20804.7        0.0
Avg Compressed Size (%)    71.2       71.2        --
Filesystems Dumped            1          1          0
Avg Dump Rate (k/s)       434.8      434.8        --

Tape Time (hrs:min)        1:37       1:37       0:00
Tape Size (meg)         14818.4    14818.4        0.0
Tape Used (%)              74.1       74.1        0.0
Filesystems Taped             1          1          0
Avg Tp Write Rate (k/s)  2606.1     2606.1        --

Is there a way of changing this to speedup backups.



You have 1 DLE, size 20 Gbyte, dumping to holdingdisk at a speed
of 434.8 Kbytes/sec. Then it is written to tape at a speed of 2606 Kbytes/sec.
Amanda cannot take advantage of parallelizing different DLE's
if there is only one.

You do have the advantage that your tape is written at the best speed, without having to stop/start the drive (bad for the tape and drive and
sometimes wasting tape capacity too).
Also, if you add more DLE's (other computers) they will be done
in parallel, and will not add much (if any) to your total run time.
So you have a nice growth path :-)

I see you also compress the backup. You can play a little with the compression settings in your dumptype:
- where to compress: 'server' or 'client (use the fastest CPU!)
- algorithm: 'fast' or 'best'  (fast can much faster than 'best')
Set something like:  "compress server fast".
(But this will not speed up your process from 434 k/s to 2600 k/s.)

Maybe you to investigate a little if there is another reason (besides
a slow file server) why the dumping is so slow.



--
# Bartho Saaiman
# Network Administrator
# Stellenbosch Automotive Engineering
# Tel :: 27 21 882 8820 x 215
# Cell :: 27 82 551 2703
# Email :: bartho @ cae.co.za


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