Hi,
On Fri, Apr 15, 2005 at 09:13:17PM +0200, Harald Finnås wrote:
centos-bounces@centos.org wrote on 15.04.2005 19:11:09:
Does anyone know of any SATA controllers that are well tested for this sort of usage?
Just have to mention it while I remember. If you decide on the 3ware 9500s controller, be aware that you HAVE to do some manual tuning. It performs like crap out of the box.
This is as good insertion point as anything else, for what i am going to say.
3ware is working like a champ, but slowly. The tuning won't make it magically go over 100MB/s sustained writes. Random I/O sucks (what i've seen) for any SATA-setup. Even for /dev/mdX. Puny oldish A1000 can beat those with almoust factor of ten for random I/O, but being limited to max. 40MB/s transfers by it's interface (UW/HVD).
But what i am going to say is that for my centos devel work (as in my NFS-server), i just recently moved my 1.6TB raid under /dev/md5 with HighPoint RocketRaid1820. I don't care that NOT being hardware RAID. The /dev/mdX beats the 3ware 9500S-8 formerly used hands down when you do have 'spare CPU cycles to let kernel handle the parity operations'.
http://www.supermicro.com/products/accessories/addon/DAC-SATA-MV8.cfm
should be even cheaper 8-port solution, but those RocketRAIDs are available on like in every store.
Google reveals that there is souce driver for these Marvel-chips (mvsata340.zip) like in
http://www2.abit.com.tw/page/en/server/server_detail.php?pMODEL_NAME=SU-2S&a...
That driver isn't exactly GPL, but it has been working quite good past month or two while i've been on my 'testing pahse' with this.
With that Supermicro board, one doesn't even have annoying BIOS problems at POST (that damn 128k BIOS init window + order of card detection etc. problems which won't always result the system you'd like to have :).
So i am not saying the 3ware isn't good solution, i am just saying that at least for me there are better solutions which gets me cheaper more compatible and faster solution. The metadevice is just something one can toss in to any hardware as it's in kernel. The 3ware needs 3ware for replacement if RAID5(0) is used. I've told that RAID1 on 3ware is just hardware mirror and those disks can be used on any controller, but i have not personally verified it.
Then few words about this '3ware driver'. How i see it, it's just a few lines wrapping linux SCSI-layer to 3ware firmware and not even doing it too good. There has been constantly talk about that the 3ware firmware would be the reason of bad performance for example CentOS-3/ext3 + 3ware. Noone out of 3ware can do anything about it and it's as it is. With kernel solution, every line of code is there and anyone can study it and find the problem if it should exist.
The now used metaformat for devices is just something which is plug'n'play. I just recently had 'a pack of disk laying around in random order' which had been 8 disk /dev/md5 and RAID5. Plugged those in a machine and found out that it was re-sunching the raid before i logged in and i just tossed those disks in w/o any knowledge about the previous order as i wasn't even going to preserve it. So the linux software implementation has grown to be pretty damn good and neat.
But then again. I need to get another cup of coffee to really wake up :P
my .02 euros