With the failure rate of SATA drives not being something to smile about, and the length of time required to rebuild arrays of this size, I am strongly inclined to recommend RAID6 to users. These days the performance hit is not that great (almost negligible) but the safety factor of being able to survive 2 simultaneous hard drive failures, or a second drive failure during a single drive failure rebuild, is, I think, worth it.

However … as drives get larger, the capacity hit of RAID6 becomes greater. “I don’t want to lose 1.5Tb capacity” is what I often hear from people when I suggest RAID6. Simply put, the increased size of the drive means increased lost capacity when moving from RAID5 to RAID6. While I think the simple solution is to just purchase more drives, it seems not everyone has my deep pockets (unsurprising as that may be in these economic times).

But … I’d strongly urge people to consider RAID6 when using large SATA hard drives to cover themselves (and their data) - and be damned with the capacity issues. I’d rather keep 14×1.5Tb data than lose 15×1.5Tb data.

Food for thought.

Ciao
Neil

Now I have a bad habit of just ignoring pop-ups (which causes me some pain occasionally), but this one had me
intrigued. Either I was asleep during some training session (not uncommon) or someone left me out of the loop. So what does this mean (the message, not the sleeping bit). I said yes and nothing exciting happened (very disappointing). That really got me intrigued so I looked at the properties of the array I had created.

My old Supermicro 815TQ is an 8-drive 2U system. Even though it looks like one backplane it’s actually considered by Supermicro (and our cards) as two backplanes … a row of 4 drives above a row of 4 drives in separate backplanes. Since I was making RAID 10s using all 8 drives, the card saw something I had not considered (and did not have control of anyway) … that it could make each pair of mirrors in my RAID 10 with one drive on each backplane for each mirror.

Simply put, if one backplane fell over, the system would keep running. The card is smart enough to see an opportunity to add an extra level of security, simply because of the configuration of my system and the raid level I was using. Cool!

The morals to the story are many … read pop-ups, stay awake during engineering briefings and when prompted to do “enclosure level redundancy” … do it.

Ciao
Neil

So what implications will that have for users?

As a venerable road warrior I live out of my laptop. Like most mobile workers I have everything I need in the laptop, and backup regularly when I get near a link that’s fast enough not to bore me to death. Currently that means LAN. ADSL, which is the most common broadband technology in this country is nowhere near efficient enough to pump large amounts of data across in a short period of time.

But what if the internet link I’m using wherever I am in the country runs at LAN speeds?

I could work from home with corporate storage access speeds that rival my current LAN access speeds when I occasionally make it to the office. All my colleagues could also work from home. Organisations that have offices in multiple locations across the country would benefit dramatically. Imagine having only one server (or cluster) for your entire organisation, rather than a complete server environment (including abackups etc) in each city. Now that will impact storage dramatically.

Cloud computing should benefit dramatically as well. Instead of having that server in the one organisation head office, it could actually reside on a service-providers network somewhere in the cloud, mean every user, whether a road warrior or office-bound worker, would have high-speed access to their data through the broadband network.

Fast data access, consistent and reliable backups, common experience for all users no matter of location (in or out of the current corporate network), centralised storage and organisation of data, easy sharing of data across corporate employees … it all sounds to good to be true.

So what impact will it have on storage? Larger, faster, centralised repositories of data, greater need for tiered heirarchy of data, increased reliance on disk2disk backups as a wider time-range of people access the same data (reducing backup windows) … the implications are many and varied.

For the moment all I can really be sure of is that there’s going to be plenty of work for people willing to dig trenches and lay cables for a few years to come. Now thats a thought … the wife is always telling me I need to get fitter

As my daughter says … bring it on!

Ciao
Neil

The question of which card to use often arises in these conversations. The 3 series card looks good because it’s cheap with lots of connectors … and price is a big consideration for these data “buckets”. So we discuss the various merits of 3 vs 5 series. “No, don’t need the performance of the 5 series” is a common statement. But what about, I ask, when things are not going so well.

The 3 series card is fine when your array is stable, optimal and all the planets are aligned, but what about rebuild times? This is where the 5 series with its extra grunt comes in handy. Rebuild times, impact on performance during a rebuild etc are questions that a lot of people don’t think about when building a system. In the past if you had a fairly small SCSI system it didn’t matter too much … the system could rebuild in the background relatively quickly without much impact on customer performance, but that’s not the case today.

When using large numbers of large drives rebuild time is an important factor. When using large numbers of sata drives impact on performance during a rebuild is also an important factor. So don’t think about specifying the products for your system for just the good times. Think about the bad times as well as make sure you put enough performance under the hood to (a) get you back up and running as quickly as possible and (b) not annoy the living daylights out of your users while this is happening.

Food for thought.

Ciao
Neil

The half-hour limit comes from the battery life on the old Lenovo. Great little laptop, but after a couple of years the battery has had the fritz. Now why is this surprising? It’s not, and that’s just the point. Everyone tells me that since I live in front of this screen it’s not surprising that my battery has died after a couple of years use. Why not just plug it in and charge it for a while? Simply because I’ve been in China where the power connectors are the same as Australia but in Hong Kong (even though it’s part of China), the power adapters are a hangover from Britain and I didn’t pack that adapter.

It’s perfectly normal and acceptable to everyone who owns one. Same goes for the mobile phone. I actually don’t even get two years out of a battery on that thing (which will be very interesting to see how long the new iphone actually lasts since apparently I can’t change the somewhat disappointing battery on that one).

So am I just waffling until the little yellow triangle tells me to go back to the Tsing Tao? No. I’ve spent a week rolling around Asia promoting various Adaptec products (which is what they pay me to do), and when I tell people that batteries on RAID cards don’t last the same life as the card … they all laugh at me.

When was the last time we changed a battery they ask? When was the last time we checked the battery? When in fact was the last time we took any notice of the battery? It’s part of the system and is fine. What’s this rubbish about batteries not lasting?

Well guess what. Batteries don’t last. Just like the mobile, or the laptop, or the (… fill in your own electronic device here), the battery on the RAID card doesn’t last.

So why did I entitle this “relativity”? Was it because I just saw a nodding little Einstein on the movie on the last flight (which was quite funny)? No, it’s because I’m always amazed that people (who are sometimes relatives of mine), have relatively naïve ideas on the relative features and capacities of two quite similar products, even when they are in completely different environments.

So guess what. Batteries don’t last. End of story.
The dreaded triangle has arrived so I’m back to the beer.

Ciao
Neil