ZFS write speed go down over time ?

T

tobiasl

Weaksauce
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Nov 19, 2007
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hi I have make a test machine to test zfs
os solaris 11 express
cpu E2200
ram 2GB DDR2
HDD 4 2TB WD Green raidz1

so I make af samba share and start to transfer the over whit 33-70mbs most 60-70mbs
but when I have transfer 1TB it dropp down to 33mb and now it only 18mbs. why it drop down so much are it cpu power it need ram use it only 600mb but when the fast transfer the cpu use whs the same. I know the setup are not the best to ZFS but I will test the rebult time befor I buy som xeon and meby jump over to zfs
 
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you need a lot more ram IMO
8GB minimum... 32gb or more for baller status
 
yes I have read zfs nede ram and I will also get som more ram it I jump but why it is a ram problem it not use it all now 600mb of 2GB
 
if it comes to performance, it is good to know:

Solaris will run with 768 MB Ram without problem.
More RAM is not needed for Solaris or ZFS but for your performance demands.

All free RAM is used for Read/ Write caching, so if you add Ram, performance will be better Usually with 4 or 8 GB Ram its ok.
If you use deduplication, you should add 2,5 GB RAM per TB Poolsize.

The same with CPU. ZFS does not need a Xeon, Intel Atom is ok.
But then you should avoid multi-user access, storage for virtual server, serverbased file editing, deduplication, encryption and prefer Raid-1 over Raid-Z.
So YOU may need a Xeon.


In your case, you have an additional performance problem with your green drives especially if they are 4k drives.
They are as cheap as they are slow. There is a good reason why the 4k thread here is as large as it is.

I have seem much better performance values with slow green drives in general when i upgraded my box from 4 to 8 GB RAM.

Your performance degration (fast and then slow down) could be due to low RAM. First it will write to RAM until there is nor more RAM and then performance degrees.
You may also try bonnie or dd to see raw disk-performance instead of SMB rates.


About SMB and Samba on Solaris

But in General i would suggest:
Samba has more options than the Solaris Kernel-based CIFS Server. But the second is faster, much more easy to use due to its ZFS integration,
Windows compatible ACL support with Workgroups and Domains and support for Windows previous version and share level-ACL.
Its not only a good Unix-Server with SMB Shares but a nearly 100% replacement of a real Windows Server

(Personally i would say its a 120% replacement, because it has much more features and much less problems)

Gea
 
thx for the help the funny think is it go up to 50mbs when I try a new HDD on my desktop so I run som speed test on my desktop but all hdd show 80mbs++ :confused:

but thinking to get

Intel Xeon DP L3426
Supermicro X8SIL-F
and 8GB ddr3 ECC

it will run as zfs filesever and a win 7 in vituelbox to do som video encoding
 
How about doing the video encoding on the native system instead of through emulation? I guess that depends on what kind of encoding and what is available for whatever os you are using. I do all my encoding in linux but the PVR is under linux as well.
 
drescherjm said:
How about doing the video encoding on the native system instead of through emulation? I guess that depends on what kind of encoding and what is available for whatever os you are using. I do all my encoding in linux but the PVR is under linux as well.
Click to expand...

yes I will like to but Handbrake can I get to work under solaris.
 
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