Subject: Re: twe status queries?
To: None <firstname.lastname@example.org>
From: Thor Lancelot Simon <email@example.com>
Date: 12/02/2005 15:24:39
On Fri, Dec 02, 2005 at 12:12:36PM -0800, firstname.lastname@example.org wrote:
> In message <Pine.NEB.email@example.com>Frank Naumann writes
> >What exact escalade raid controller do you have? The performance
> >difference is normal for the escalade 7000/8000 series. This is because
> >Raid5 is accelerated by the so called R5 fusion technology on this
> >controller (hardware XOR engine or something like that). The problem is
> >that the escalade 7000/8000 can only accelerate one Raid5 array with this
> >technology (so additional Raid5 arrays are much slower). Btw. this is
> >mentioned in detail somewhere in the escalade users manual.
> hi Frank,
> I find that a fascinating detail. Do you know of a comparable (12-port
> or more) escalde series which can support 12-drive or greater configs,
> and which also offers at least one of:
You'd need a 9500 series card, and we don't have a driver for those at
the moment. The FreeBSD driver treats them as SCSI host adapters, so
porting it would not be trivial (Andy Doran, with minimal help from erh
and I, ported the structurally similar 'mly' driver over a weekend a few
years ago, but it was a _painful_ weekend for all involved) though it
would certainly be possible.
The 7500/8500 series 3ware cards are pretty cheezy, IMO. The "R5 Fusion"
is just a stripe cache, and indeed it's only large enough to cache one
stripe at a time -- so they just give it to the first array you configure.
Their error reporting is not very good and their performance is just so-so.
You can boot from a RAIDframe RAID 0 mirror and keep most of your data on
a RAIDframe RAID 5 set. It's not an ideal solution but it should work.
Another option but with less ports than you want would be the LSI MegaRAID.
The newest ones at least have 8 ports (they're PCIe or PCI-X), have large,
*battery backed* nonvolatile cache to speed up RAID 5, and should, AFAICT,
work withour driver -- or, if they don't, the changes necessary to make them
work should be easier to take from the FreeBSD driver than doing a full
port of twa.