For performance a single replica is best: many things take twice as long
with two replicas, e.g. storing a file.

We will be coming out with write back caching: this will hugely improve 
tar zxvf linux.tgz

To see how much the improvement will be you can do the following:

0. use 4.6.5

1. venus-init server 200000 (200MB is a midsize cache)

2. clog (VITAL)

3. cfs wd -age 5 -time 5
This write disconnects the client, and starts writing back at most 1 sec
later and then allows quite a lot of stuff to be sent in one blow (namely
for 5 secs)

4. now tar zxvf your-kernel.tgz

- Peter -


On Wed, 16 Sep 1998, Troy Benjegerdes wrote:

> Well, I set up two coda servers and a volume replicated on both servers,
> and ran the Bonnie filesystem benchmark on nfs and coda. I also untarred a
> linux kernel to check file creation times.
> 
> The machines were new Asus P2DS 100Mhz RAM motherboards with one Pentium
> II 450 and a 4 GB Western Digital IDE drive. Each machine has 256MB off
> RAM. The machines were connected via Fast ethernet and a Bay Networks
> switch.
> 
> The venus cache size was also set 20 MB.
> 
> Both machines were running codasrv and venus, and bonnie was run on the
> second machine.
> 
> For the 30 MB file size, coda actually beat nfs for block writes. On block
> reads for the 30MB size, NFS was over 10 times faster... I believe this to
> be because NFS is using the linux-buffer cache to it's advantange. Does
> the coda fs module use the buffer cache as much? I am using the module
> that comes with the 2.1.121 linux kernel.
> 
> For the untarring, coda was *much* slower. I'm assuming this is because
> file creation has a lot of overhead and such.
> 
> All in all, I am quite impressed, and coda quite looks quite promising
> as a base filesystem for a Beowulf-type cluster environment. My next goal
> is to get 6 more identical machines set up (for a cluster of 8) and check
> how coda performs. Does anyone have any suggestions on how many servers I
> should run? I believe two is the minimum for data redundancy, and 8 (one
> one each machine) would be overkill.
> 
> Here are the results:
> 
> Coda filesystem, replicated on 2 servers, 300MB test file
> 
>        -------Sequential Output-------- ---Sequential Input-- --Random--
>        -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>     MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU 
>    300  1474  8.3  1629  2.3  1022  4.7  1420  5.8  1380  3.4  19.1 0.2
> 
> NFS filesystem, 300MB test file
> 
>        -------Sequential Output-------- ---Sequential Input-- --Random--
>        -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>     MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>    300  2268 13.7  2226  2.4  1150  3.9  2702 13.2  2603  4.7 219.8 2.0
> 
> Coda filesystem, replicated on 2 servers, 30MB test file
> 
>        -------Sequential Output-------- ---Sequential Input-- --Random--
>        -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>     MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>     30  3256 17.9  4405  5.7  3134  7.7  2007  7.3  3474  3.1 378.6 2.0
> 
> NFS filesystem, 30 MB test file
> 
>        -------Sequential Output-------- ---Sequential Input-- --Random--
>        -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
>     MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
>     30  2831 13.0  2216  3.3  3181  8.4 28403 99.9 115432 101.5 2790.6 18.8
> 
> 
> 
> Untarring linux-2.1.121 on nfs:
> 
> [troybenj_at_mos11 test]$ time tar zxvf /tmp/linux-2.1.121.tar.gz  
> 
> 4.18user 3.97system 1:14.74elapsed 10%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (3163major+9197minor)pagefaults 0swaps
> 
> 
> 
> --------------------------------------------------------------------------
> | Troy Benjegerdes    |    troybenj_at_iastate.edu    |    hozer_at_drgw.net   |
> |    Unix is user friendly... You just have to be friendly to it first.  |
> | This message composed with 100% free software.    http://www.linux.org |
> --------------------------------------------------------------------------
>