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Dot Hill with Xsan
The Promise Vtrak is the only officially supported platform that can be used to provide LUNs to an Xsan. Having said that, there are a number of other storage vendors that are supplying LUNs at this point. And while I don’t really want to speak to that it is worth noting that it brings me joy to watch the ever-expanding number of vendors testing their products for and then marketing to the Xsan community. One that I came across recently is Dot Hill, who did a video showcasing their speedy 2U product at NAB.
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Defining MultiSAN
In Xsan 2, MultiSAN was introduced. MultiSAN allows you to assign different sets of primary, secondary and tertiary metadata controllers to volumes. This provides a performance benefit for some environments that have saturated resources on a given metadata controller. However, MultiSAN does not allow you to build separate SANs. All of the volumes are still members of that single “Xsan”, meaning that volumes can be mounted and/or controlled for any of the clients. You can have 2 volumes, each with a dedicated metadata controller, but both sharing a single backup metadata controller. You can also have 2 volumes, each with a dedicated metadata controller that fails over to the other…
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Post at Xsanity on Active Storage
Posted a little article on Xsanity about the new press releases from Active Storage regarding Innerpool and Active Stats. You can find it here: http://www.xsanity.com/article.php/20100415165329925
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Don't Defrag the Whole SAN
I see a numer of environments that are running routine defragmentation scripts on Xsan volumes. I do not agree with this practice, but given certain edge cases I have watched it happen. When defragmenting a volume, there is no reason to do so to the entire volume. Especially if much of the content is static and not changing very often. And if specific files doesn’t have a lot of extents then they are easily skipped. Let’s look at a couple of quick ways to narrow down your defrag using snfsdefrag. The first is by specifying the path. In this case you would specify a -r option and follow that with…
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Isolating iNodes in Xsan cvfsck Output
I’ve noticed a couple of occasions where data corruption in Xsan causes a perceived data loss on a volume. This does not always mean that you have to restore from backup. Given the cvfsck output, you can isolate the iNodes using the following: cat cvfsck.txt | grep *Error* | cut -c 27-36 > iNodeList.txt Once isolated you can then use the cvfsdb tool to correlate this to file names. For example, if you have an iNode of 0x20643c8 then you can convert this into a file name using the following: cvfsdb> show inode 0x20643c8 The output will be similar to the following: 000: 0100 8000 3f04 0327 5250 2daa 0000…
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Uniq Logs
Recently I’ve been looking at a lot of log files. And sorting through them can be a bit of a pain. However, there are some tools out there to help make this process a bit easier. The first of these is sort. If I have a log that has 1,000 lines, while I like to initially see any lines that are repeated numerous times so that I can see when servers are throwing a lot of errors, combing through them can get tedious. Sort will help to reduce the volume and organize them in a manner that makes sense. For example, to sort the logs and remove duplicate line entries…
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Blessing the blessed
The bless command can be used to read your currently blessed operating system in Mac OS X. You can also leverage it to set an operating system in Mac OS X. Don’t ask why, but I recently needed to read what my blessed operating system was and set my blessed operating system to the same volume. Much like choosing a volume in the Startup Disk System Preference pane when I’m already booted to that volume. With a little help debugging, here’s what I came up, in case anyone : myDisk=”$(/usr/sbin/bless –getBoot)” myDiskOutput=”$(/usr/sbin/diskutil info “$myDisk” | grep “Volume Name” | cut -c 30-60)” bless –mount /Volumes/”$myDiskOutput” –setBoot echo $myDiskUtilOutput > /tmp/booter.txt…
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Disable Spotlight for Xsan Volumes
I’ve seen a number of Xsan environments spewing tons of errors in regards to Spotlight this and Spotlight that. Yup, that is with Spotlight disabled on the volumes. You can use the mdutil command to help with this. If you have two volumes, then the script to do so would be similar to the following (assuming they are called A and B): mdutil -i off /Volumes/A mdutil -i off /Volumes/B Later if you decide to implement Spotlight, you can use the following to re-enable indexing: mdutil -i on /Volumes/A mdutil -i on /Volumes/B
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SMB, Extended Attributes & Xsan
Xsan 2.2 is having a bit of a problem with serving up files with Extended Attributes over SMB volumes that are stored on an Xsan according to a recent knowledge base article. The fix (other than not using files with Extended Attributes on Xsan volumes that are shared up over SMB is to enable stream support in the /etc/smb.conf file. To do so, open /etc/smb.conf and then change the stream support = yes setting to stream support = no. This isn’t to say that all of your problems will magically vanish, but it should help to provide some relief until the next update.