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Posts in Storage
ZFS dataset and volume properties
A few chapters of the upcoming OpenSolaris Bible have been released. Specifically, looking through chapter 8 on ZFS, I came across this handy list of properties and their descriptions. Some of these properties were new to me, as they probably only exist in later versions of ZFS in OpenSolaris. Specifically, vscan, to scan files for viruses is interesting…
$ read more →Figuring out if a dedicated ZFS intent log will help
ZFS uses the ZFS intent log (also referred to as a ZIL) to store synchronous writes. This has the advantage that a full transaction group doesn't need to be written when a synchronous write occurs, and maximizes the use of I/O bandwidth. For some applications (databases come to mind), placing the ZIL on a dedicated device can be extremely helpful. But how can you tell if placing the intent log on a separate device would be useful…
$ read more →zpool shrink / evict is almost here
The inability to remove devices from ZFS Zpools has been one of the most annoying / inflexiable things about ZFS. I once read a blogpost about somenone who added a USB flash stick into the root ZFS pool, and now the USB stick became a perminent fixture of the machine! There was no simple way to fix this issue other than backup / network dump / rebuild machine / network restore. Matthew Ahrens workedon changing the ZFS scrub code in SNV 94 (which made its way into the Fishwork's Amber Road NAS Appliance), but this work will also lay the groundwork for "zpool evict" or the such…
$ read more →SCSI Enclosure Services
Eric Schrock has done some really cool work with integrating disk (SMART) /platform monitoring (IPMI) information into Opensolaris. Just recently, he has extended FMA with a new technology called SES (SCSI Enclosure Services) into build 93 of OpenSolaris. This looks like some really cool stuff. The following was taken directly from his blog on the examples of using the new fmtopo utility to map out an external storage array.
$ read more →The wonderful world of Leadville
In a SAN environment when dealing with external storage concepts such as EMC BCV's, you'll often have a request to create volumes on two different machines that are identical so replication on the back-end can occur. When you look at a LUN presented to Solaris, it'll appear with a cryptic name like the following: The c20 relates to the HBA (Fiber, SCSI, iSCSI) that provides a path to the device. The "middle" sequence 60060480000190100665533030393836 between the "t (target)" and "d (device" is the WWN of the LUN. Now, say your SAN engineer approaches you with some information like the following…
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