Wednesday Jul 02, 2008

Multipathing for Tape

It was a dark and stormy night, the back up windows opened and shut with the regularity of a 90 year old pensioner's clacking of teeth as he snored with the flem filled nervousness of old age and incontinence. The data flowed from the backing store to fixed content archives like a humpback whale strains plankton. The administrator anxiously clacked her gum back and fourth against the two teeth she had recently had crowned with a couple of diamonds (one shaped like an "i" the other clearly an "o"...some of the geeks at work thought it was a one and a zero, but, they don't understand IO) as she watched the progress of her back up. All of a sudden there was a rigid silence as the status window showed zero throughput and the tortured silent scream of failed IOs bounced off the ear buds of the administrator. With manic obsessiveness the administrator chanted her mantra "If an IO fails to complete, is it ever an IO?" and she anxiously counted off the seconds before the back up timed out. ....Over and over again she chanted her mantra as the digital clocked ticked with the slowness and regularity of a clock:

7..8..9..."...fails to complete..." 17...18....19... "is it ever an IO?"....28...29... (occasionally she changed her mantra to "I think I can I think I can" as she took power hits of her RedBull) 47...48...49... And then, with the almost ecstatic relief one feels as a particularly large boil is lanced, the IO kicked back in down the alternate path and the back up proceeded. 

So, with a rather shameless head nod towards the "The Bulwer-Lytton Fiction Contest" I announce that we have integrated multipathing for tape into Solaris build 93. This is the culmination of a lot of work in both the ST driver as well as MPxIO. In particular, we have solved the problem of logical block addressing and error recovery as well as true multi-pathing to multi ported tape drives. Additionally, this is a platform for innovation as well. Now that we have highly available tape back up windows that are natively part of the Solaris operating system (you could do some of this before with FCP2 Error recovery, but it wouldn't help with a bad HBA or cable) we can look at bus saturation so we can attempt to drive down back up times.

A strong head nod towards our experts in tape and MPxIO. Well done Randy and Wayne

Wednesday Jun 11, 2008

I need a code review


I need a code review. Randy, one of my whiz developers is ready to integrate his MPxIO for tape changes in build 93. This is a cool project and pretty bleeding edge. Great work and we need a code review. C'mon... Give a guy some help!

Best code reviewer gets a gift package from me. Cool Solaris stuff. I decide who the best code reviewer is. My decision is final and can not be swayed unless the review is delivered on the hood of a brand new car. (OK, minivan, I have lots of kids now..)

Seriously, help a guy out. Heck, post the review in my comments section... Just make sure you include your email address...


Sunday Jul 15, 2007

Something borrowed-- Using the work of others and extending on a theme...

A note about the title:

I am going to "borrow" a post from David Weibel, a former Sun engineer. He writes well and he is also an excellent engineer. You can also borrow Sun equipment. Hopefully it will lead to a nice marriage. And, of course, I borrow the catchphrase of a world class New Orleans chef. Onwards...

I just got off a phone call with a vendor trying to implement high-availability on a Solaris client using their iSCSI target. I was gratified to hear how painful it was in other operating systems (and, by extension, painless in Solaris). Here at Sun, we try to make it simple to use the storage stack. Conform to the standard, and it should just work. Particularly if the device is standards-based. Asymmetric, roll your own, hand-crafted devices are great for tinkering, but if you want a world class storage subsystem, you should probably use a standards-based product.

 Here is a link to David Weibel's blog entry on iSCSI and MPxIO, showing how simple it is to hook up a standards based array.

Now, as Emeril Lagasse might say, "Let's kick it up a notch." BAM.  Imagine you want to build that storage device using Solaris as your storage operating system on the array. Hey, you can do that too, now that the Availability Suite, the iSCSI Target, and ZFS are all part of the operating system. Check it out on The world moves on. Value moves up the stack. A world class operating system with data services, RAID functionality and some of the best plumbing in the industry. Now all you need is a Thumper and a couple of X4600s to run it on.

Did you know you can try out a Thumper, an X4600 and AVS free for 60 days? Try it. Buy if you like it. Send me a note or a comment if you want to try this product set.


Also, 'cause I dig good food and good writing, check out this link. The author writes the review so well I gain virtual weight every time I read about the food she eats. 





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