[OpenAFS] Speed tests on our AFS Cell

[Lars Schimmer]

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Hi!

Another try to optimize our speed in ou AFS Cell.

Setup is:
1. databaseserver with 1.3.79 and MIT kerberos5
2. Fileserver with 1.3.81-3 and SATA HD and Athlon XP 2000+
3. Client with 1.3.81-3 PATA HD and Athlon XP 2000+
DiskCache on both.

Fileserver is OpenAFS only, so no other jobs on it.
Client is Desktop machine with some other load (XMMS, Firefox, Thunderbird,
XChat, Konquerer).
Both are Debian sarge, server is 2.6.11 kernel, client is 2.4.27 kernel.
Both are 3com cards set to 100Mbit FD, and FTP from one to another shows line
speed with >10 MB/sec.

Some simple tests I made:
Copy 51 Mb from client to server:
real    0m10.180s
user    0m0.000s
sys     0m3.720s
~ (roughly 5 MB/Sec)

Without flushing the cache, it can read it back in .5 sec (hence, the local cahce).
But after a fs flush and a fs flushmount the time doesn't change, so there's
something strange ;-)

Now unrar a 500 MB file from 35 .rarXX files into AFS is nice, to.
With some "simple" traffic graph like gkrellm, it shows 6-8 MB/Sec, nice and
fast. But the traffic isn't a contineous line, it burst for some 50-60 MB at
that rate, fall down to nearly 0, wait some sec and burst again at high rate.
I assume that's the cache to be filled again.
Read back that 500 MB File to another dir on client shows a rate of 7-8.5
MB/sec, constant, without bursts.
Time rate of that shows:
real    1m22.886s
user    0m0.060s
sys     0m4.880s
Size: 561619968 Byte

Now something different:
copy that 5xx MB file from fileserver 1 to another fileserver with time cp path1
path2. But why does the client has traffic over the line? Doesn't AFS sync that
kind of traffic direct from server to server?
Anyone?

Readrate is pulsed, write rate is pulsed. It first reads at 8 MB/Sec, than write
at 4-5 MB/sec, reads, write, and so on and so on.
Fileserver 2 is a debian sarge with 1.3.79, PATA PCI controller, 100Mbit and a
dual PIII at 500 Mhz.
Strange that write rate differs so much (3-4 MB/Sec), later if I update that AFS
Version, I can tell if it's the AFS version or the CPU.
Time rate for that copy:
real    3m46.267s
user    0m0.020s
sys     0m47.830s

Read from Fileserver2 the 5xx MB file gives constant rates at 4 MB/sec roughly.
Time data:
real    2m25.141s
user    0m0.050s
sys     0m4.760s

So I may tell you: speed of fileserver 1 is OK, fileserver 2 not. Although
better than 1-2 MB/sec we had before some changes here.

Another question I've got is about cache-size:
I read somewhere to set cache size to roughly 1 GB on disk cache. Is it a real
nice one to set such a big cache at normal work or is it more like a showstopper
and 50-100 MB Cache is better?

Thx so far
Lars Schimmer
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Technische Universität Braunschweig, Institut für Computergraphik
Tel.: +49 531 391-2109            E-Mail: schimmer@cg.cs.tu-bs.de
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