Dave Johnson wrote: > You may want to read this thread and try the respective patches but > the best difference for writes where cache pressure is low (cache size > is much larger than write-back cache fill rate) is claimed by testing > at approximately 1.8, aka 80% faster on linux md:
*Very* nice indeed. > > http://thread.gmane.org/gmane.linux.raid/14997 > > The aformetioned thread is regarding write-back cache patches for md. > > I for one fail to see how write-back caching on an UPS-protected > system using the linux md driver is any different than a hardware > battery-backed write-back cache except that the cost of providing the > same amount of protection time for the linux system vs the hardware > cache is much higher. Futhermore, nuts can be monitored and md > informed to disable write-back cache upon tranistion to UPS power in > the event of utility power failure. Comments ? All good points. R. > > -=dave > > ----- Original Message ----- From: "Rafiu Fakunle" <[EMAIL PROTECTED]> > To: "Dave Watkins" <[EMAIL PROTECTED]> > Cc: <[email protected]> > Sent: Monday, July 23, 2007 2:38 AM > Subject: Re: [OF-users] Getting I2O RAID to work > > >> Dave Watkins wrote: >>> Excuse the top posting, I'm stuck on OWA :) >>> >>> There are still some additional benefits if you really need speed, and >>> they are the onboard memory hardware raid cards have, and the ability >>> to add a BBU so you can turn on write-back caching and geta nice speed >>> boost for doing it. >> >> It'd be interesting to see some numbers of SAS RAID with cache and >> write-back vs softraid.... >> >> >> R. >>> >>> Dave >>> >>> ------------------------------------------------------------------------ >>> >>> *From:* [EMAIL PROTECTED] on behalf of Rafiu >>> Fakunle >>> *Sent:* Sat 7/21/2007 3:13 p.m. >>> *To:* Dave Johnson >>> *Cc:* [email protected] >>> *Subject:* Re: [OF-users] Getting I2O RAID to work >>> >>> Dave Johnson wrote: >>> > i for one would like to start the trend of ceasing to call these >>> > "RAID" cards, since they aren't, >>> >>> Hear hear. >>> >>> > and instead calling them exactly what they are, >>> >>> Lemons! ;) >>> >>> > storage device controller cards with an integrated -but for all >>> > intents and purposes- outboard XOR Offload Engine (XOE). >>> > >>> > XOE (zo-wee) cards are notorious for failing on you at the most >>> > inopportune time. I 2nd Rafiu's recomendation to go with a complete >>> > RAID subsystem which includes XOE, storage device controller, and >>> data >>> > transport IO processor all in one complete card. Or simply not use >>> > the XOE of the card and use only the storage controller portion, >>> > relying instead on the RAID support within the LVM2 component, which >>> > has been designed and vetted for safety by considerably more testing >>> > than Promise' 5 beta testers in Taiwan. >>> > >>> > That XOE can be a biotch ! =P >>> > >>> >>> You know, with the average CPU having at minimum 2 cores, the only >>> advantage to using a RAID controller these days - when you weigh >>> softraid against the management overhead of hardraid - is for the >>> hot-swap capability. Otherwise a decent SAS controller + MD RAID and >>> you're good to go. External RAID is a different matter of course, >>> especially when you get into the realm of shared storage. >>> >>> >>> R. >>> >>> > -=dave >>> > >>> > ----- Original Message ----- From: "Rafiu Fakunle" > >>> <[EMAIL PROTECTED]> >>> > To: "Jim Kusznir" <[EMAIL PROTECTED]> >>> > Cc: <[email protected]> >>> > Sent: Friday, July 20, 2007 3:48 PM >>> > Subject: Re: [OF-users] Getting I2O RAID to work >>> > >>> > >>> >> Jim Kusznir wrote: >>> >>> Hi all: >>> >>> >>> >>> After over a week of messing with OpenFiler, I think I'm finally >>> >>> close >>> >>> to getting my hardware I2O RAID card working (Promise SX6000). >>> I had >>> >>> to upgrade the kernel, as the version shipping with OF has a bug >>> in >>> it >>> >>> that breaks all I2O RAID cards. I don't need iSCSI target for >>> now, >>> so >>> >>> I though tthis was acceptable. >>> >> >>> >> Don't use i2o cards ;) >>> >> >>> >> Stay away from anything named "Promise" or "Highpoint" if you want >>> OF to >>> >> play nice with the RAID Controller. >>> >> Cards we tend to play better with are: >>> >> >>> >> 1) 3Ware / AMCC >>> >> 2) Areca >>> >> 3) LSI Logic / Intel >>> >> 4) Adaptec >>> >> 5) ICP Vortex >>> >> >>> >>> >>> >>> Now that I have it showing up in my system, things are close. The >>> >>> problem is I2O raid devices are created in /dev/i2o/hd* (my case: >>> >>> /dev/i2o/hda -- this is NOT the same disk as my system disk: >>> >>> /dev/hda). So, under "Physical Volues", it does not see it, and >>> thus >>> >>> I can't partition or use it. I have verified that the volume >>> itself >>> >>> works by partitioning and formatting it directly. Both operations >>> >>> completed sucessfully, verifying the raid drivers funcitionality. >>> >>> >>> >>> So my question at this point is: how do I get OF to see the disk >>> and >>> >>> be able to create volumes and such. Or, if I partition and set >>> up >>> LVM >>> >>> by hand, will it pick it up at that point? If so, what are its >>> >>> requirements to make it seen? >>> >> Here's a patch to /opt/openfiler/sbin/list-disks.pl >>> >> >>> >> --- list-disks.pl.orig 2007-07-20 15:18:22.000000000 -0700 >>> >> +++ list-disks.pl 2007-07-20 15:26:24.000000000 -0700 >>> >> @@ -123,6 +123,7 @@ >>> >> close(MEDIA); >>> >> if ($media =~ /^disk/ && !$_[0]) { >>> >> push(@devs, "/dev/hd$n"); >>> >> + push(@devs, >>> "/dev/i2o/hd$n"); >>> >> } >>> >> } >>> >> } >>> >> >>> >> >>> >> >>> >> R. >>> >> _______________________________________________ >>> >> Openfiler-users mailing list >>> >> [email protected] >>> >> https://lists.openfiler.com/mailman/listinfo/openfiler-users >>> >> >>> > >>> > _______________________________________________ >>> > Openfiler-users mailing list >>> > [email protected] >>> > https://lists.openfiler.com/mailman/listinfo/openfiler-users >>> >>> _______________________________________________ >>> Openfiler-users mailing list >>> [email protected] >>> https://lists.openfiler.com/mailman/listinfo/openfiler-users >>> >>> ------------------------------------------------------------------------ >>> >>> >>> _______________________________________________ >>> Openfiler-users mailing list >>> [email protected] >>> https://lists.openfiler.com/mailman/listinfo/openfiler-users >>> >> >> _______________________________________________ >> Openfiler-users mailing list >> [email protected] >> https://lists.openfiler.com/mailman/listinfo/openfiler-users >> > > _______________________________________________ > Openfiler-users mailing list > [email protected] > https://lists.openfiler.com/mailman/listinfo/openfiler-users _______________________________________________ Openfiler-users mailing list [email protected] https://lists.openfiler.com/mailman/listinfo/openfiler-users
