Happy new year! Snowing here and my new year party was cancelled. Ok, let me do more boring IT stuff then.
Orvar, sorry I misunderstood you. Please feel free to explore the limitations of hardware RAID, and hopefully one day you will come to a conclusion that -- it was invented for saving CPU juice from disk management in order to better fulfill the application needs, and that fundamental driver is weakening day by day. NetApp argued that with today's CPU power and server technologies, software RAID can be as efficient and even better if it is done right. And Datacore went beyond NetApp by enabling a software delivery to customers, instead of an integrated platform... Anyway, if you are still into checking out HW RAID capabilities, I would suggest to do that in a categorized fashion. As you can see, there are many many RAID cards at very very different price points. It is not fair to make a statement that covers all of them. (and I can go to china tomorrow and burn any firmware into a RAID ASIC and challenge that statement...) Hence your request was a bit too difficult -- if you tell the list which HW RAID adapter you are focusing on, I am sure the list will knock that one off in no time. ;-) http://www.ciao.com/Sun_StorageTek_SAS_RAID_Host_Bus_Adapter__15537063 Best, z, bored ----- Original Message ----- From: Tim To: Miles Nordin Cc: zfs-discuss@opensolaris.org Sent: Wednesday, December 31, 2008 3:20 PM Subject: Re: [zfs-discuss] ZFS vs HardWare raid - data integrity? On Wed, Dec 31, 2008 at 12:58 PM, Miles Nordin <car...@ivy.net> wrote: >>>>> "db" == Dave Brown <dbr...@csolutions.net> writes: db> CRC/Checksum Error Detection In SANmelody and SANsymphony, db> enhanced error detection can be provided by enabling Cyclic db> Redundancy Check (CRC) [...] The CRC bits may db> be added to either Data Digest, Header Digest, or both. Thanks for the plug, but that sounds like an iSCSI feature, between storage controller and client, not between storage controller and disk. It sounds suspiciously like they're advertising something many vendors do without bragging, but I'm not sure. Anyway we're talking about something different: writing to the disk in checksummed packets, so the storage controller can tell when the disk has silently returned bad data or another system has written to part of the disk, stuff like that---checksums to protect data as time passes, not as it travels through space. The CRC checking is at least standard on QLogic hardware HBA's. I would imagine most vendors have it in their software stacks as well since it's part of the iSCSI standard. It was more of a corner case for iSCSI to try to say "look, I'm as good as Fibre Channel" than anything else (IMO). Although that opinion may very well be inaccurate :) --Tim ------------------------------------------------------------------------------ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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