Accidentally deleted the partitions on my boot disk. The system is still running. How can I recover?

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http://unix.stackexchange.com – I just accidentally scrubbed all the partitions from the wrong disk. /dev/sda is the boot disk, and /dev/sdb is a new disk I am trying to set up as a RAID mirror. I accidentally fat-fingered it, and wound up deleting the partition table on /dev/sda, rather then /dev/sdb. The system is still up and running, so it's running off a cached partition table somewhere. Can I recover the partition table, or at least view it, so I can recreate the partitions exactly where they were? fdisk /dev/sda -l yields no partitions. Yeah, I feel clever (HowTos)