Hi Mark; You suggest FCP for larger disk allocations, and we've looked at that here, but we've back-burnered it for two reasons.
The first is mirroring. With our mainframe DASD, we get mirroring for free (meaning that it requires no software or CPU time or additional I/Os within our Linux guests). If we start using FCP, suddenly we have to do our own mirroring in Linux, which means double the I/O, more CPU, and additional software in the install to support it. Also, current Linux mirroring does not keep duplicate copies of the mirroring index, meaning that if you lose the master of the mirror set which contains the index, once it's back up your only choice is to re-mirror the entire disk, or set of disks. We've had to do this in our Intel Linux environment; it took several days for it to catch up. The second is multipathing. Again, using DASD, this is entirely free, and handled at the controller level. Doing so with FCP requires additional software in Linux to set up the redundant paths, and this translates into more CPU expended to provide the feature. These two bottlenecks have kept us from trying to exploit FCP. We mirror and multipath everything, in all environments (mainframe, Intel Linux, Solaris, AIX...), so it isn't just a special project consideration; it's a requirement for installing a system here. (We're a medical facility; we like things to survive, be it patients or computers. :-) -- Robert P. Nix Mayo Foundation .~. RO-OE-5-55 200 First Street SW /V\ 507-284-0844 Rochester, MN 55905 /( )\ ----- ^^-^^ "In theory, theory and practice are the same, but in practice, theory and practice are different." On 3/13/08 5:01 PM, "Mark Post" <[EMAIL PROTECTED]> wrote: > To be able to use striping, you need more than one virtual disk/minidisk. > Mod-54s sounds like you're planning on a lot of data. SCSI over FCP should be > considered at that point. ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
