Re: [Networker] Poor performance backing up netapp filer via FC to LTO-3

 
How is your client savesets defined, by volume or by qtree, or "ALL"? How large 
are your volumes? How many files? What version of OnTAP and Legato are you 
running? What level of NDMP are you set? 

When doing NDMP backups, Legato issues a command to the client to start the 
backup. The actual backup datastream is defined by the client, not Legato. In 
NetApp's case, they use a modified ufsdump. It isn't the most efficient, but it 
is reliable. It also is very serial oriented and has a hard time keeping the 
drives spinning at full speed. In fact, there is a tape media issue with 
"back-hitching or shoe-shining" using NetApps. The LTO-3 is better at handling 
that though.

When 7.2 was released we migrated away from having the tape drives attached 
locally to our NetApps and instead streamed the backups via TCP/IP. This 
allowed a number of things. First it allowed us to share the tape units with 
other backups (without using DDS). In 7.2 you can stream the NDMP backup within 
a Legato datastream so it can parallelize it with other backups. By doing this 
and backing up a the qtree level, we greatly increased our backup speed.

In order to get that backup speed, we had to configure a separate VLAN with a 
dedicated Gigabit ethernet card in our NetApp and backup server. We are running 
Ethernet Jumbo frames with some TCP tuning on our Sun Solaris box to increase 
the window sizes and buffers. Our full backups went from 18 hours to around 5-6.

tcp tuning parameters:

ndd -set /dev/tcp tcp_max_buf    4194304
ndd -set /dev/tcp tcp_cwnd_max   2097152
ndd -set /dev/tcp tcp_xmit_hiwat 1048576
ndd -set /dev/tcp tcp_recv_hiwat 1048576
ndd -set /dev/tcp tcp_tstamp_always 1
ndd -set /dev/tcp tcp_wscale_always 1

We also tuned our Gigabit adapter:

/platform/sun4u/kernel/drv

name="pci100b,35" parent="/pci@8,700000/pci@2" unit-address="0" adv_pause_cap=1 
accept-jumbo=1 infinite_burst=1 rx_dma_weight=3;
name="pci100b,35" parent="/pci@9,700000"       unit-address="2" adv_pause_cap=1 
infinite_burst=1 rx_dma_weight=3;
name="pci100b,35" parent="/pci@9,600000"       unit-address="1" adv_pause_cap=1 
infinite_burst=1 rx_dma_weight=3;

--
Matthew Huff           | One Manhattanville Rd
Director of Operations | Purchase, NY 10577
OTA LLC                | Phone: 914-460-4039 
mailto:mhuff AT ox DOT com    | Fax:   914-460-4139   
-----Original Message-----
From: Legato NetWorker discussion [mailto:NETWORKER AT LISTSERV.TEMPLE DOT EDU] 
On Behalf Of Ronny Egner
Sent: Saturday, November 19, 2005 5:11 AM
To: NETWORKER AT LISTSERV.TEMPLE DOT EDU
Subject: [Networker] Poor performance backing up netapp filer via FC to LTO-3

Hi list,

we are backing up our netapp filer by ndmp. The tape drive is connected via 
fibre channel. We upgraded the drive from lto-2 to lto-3 recently. However: the 
backup performance  havent changed since then (approx 25 mb/s). The new lto-3 
drive should come up with more than 50 mb/s....

Any help ?


-- 



Mit freundlichen Grüßen

Ronny Egner

SIV.AG
Konrad-Zuse-Straße 1
18184 Roggentin

Telefon: +49 (0)3 81 / 25 24 422
Telefax: +49 (0)3 81 / 25 24 399

mailto:ronny.egner AT siv DOT de
http://www.siv.de

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