Benjamin Marzinski napisał(a):
> On Tue, Mar 27, 2007 at 10:22:01PM +0200, David Shwatrz wrote:
>> Hello,
>> In short: what are the advantages/disadvantages when using GNBD versus
>> iSCSI for exporting storage in a cluster?
>
> The only real advantage of using GNBD is that it has built in fencing. With
> iSCSI, you still need some somthing to fence all the machines (unless your scsi
> target supports SCSI-3 persistent resrvations). Theoretically, GNBD could
> run faster, since it doesn't need to do the work to imitate a SCSI device, but
> but there's a lot of work that needs to be done for GNBD to reach it's speed
> potential. Since there isn't much active development of GNBD, if iSCSI
> isn't already faster than it, it will eventually be. I am pretty much the only
> GNBD developer, and aside from bug fixing, I do very little work on it. iSCSI
> has an active community of developers. Using iSCSI also allows a much more
> seemless transition to a hardware shared storage solution later on.
>
> If you don't have any fencing hardware, and your iSCSI target doesn't support
> SCSI-3 persistent reservations, then you should probably go with GNBD. Otherwise
> it's up to you.
Hello,
Disadventage of using GNBD is that it doesn't support
authorization/authentication, so it could be a problem in some
configurations.
Here is comparison test with or without GNBD
hardware:
- kernel: 2.6.18-8.1.1
- Procesor: 2x Intel(R) Xeon(TM) CPU 2.80GHz
- Memory: 2GB
- SCSI DISC: MAXTOR Model: ATLAS10K5_146SCA Rev: JNZ6
- Filesystem: ext3
1. local test(/dev/sdb1)
[root@blade03-1 ~]# bonnie++ -d /mnt -s 4g -u root
Version 1.03 ------Sequential Output------ --Sequential Input-
--Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
blade03-1 4G 35829 86 93034 43 35334 13 46666 93 84543 11
484.2 1
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
+++++ +++
blade03-1,4G,35829,86,93034,43,35334,13,46666,93,84543,11,484.2,1,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++
2. GNBD test(/dev/gnbd/sdb1)
- 1Gbit network(Nortel Layer 2/3 Copper GbE Switch Module for BladeCenter)
[root@blade02-1 ~]# bonnie++ -d /mnt -s 4g -u root
Version 1.03 ------Sequential Output------ --Sequential
Input---Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block--
--Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP
/sec %CP
blade02-1 4G 19724 50 20362 11 13391 7 31688 70 79717 16
360.0 0
------Sequential Create------ --------Random
Create--------
-Create-- --Read--- -Delete-- -Create-- --Read---
-Delete--
files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP
/sec %CP
16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++
+++++ +++
blade02-1,4G,19724,50,20362,11,13391,7,31688,70,79717,16,360.0,0,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++
[root@blade02-1 ~]#
Best Regards
Maciej Bogucki
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