How Many IOPS?

A question I get asked occasionally is; “How many IOPS can my RAID group sustain?” in relation to Enterprise class arrays. Obviously the first question is to determine what the data profile is, however if it isn’t known, then assume the I/O will be 100% random. If all the I/O is random,...

September 2nd, 2008 | Uncategorized | Read More

The Defrag Debate

I was asked again this week whether defragging of hard drives on Windows servers is really necessary. This is quite pertinent as the cost of deploying an enterprise-wide defrag tool can be significant and any opportunity to save money has to be a good one. I discussed fragmentation last year (here)...

July 21st, 2008 | Uncategorized | Read More

SPC

According to Wikipedia, lightning can travel at a speed of 100,000 MPH, however I think storage vendors are even faster than lightning when it comes to highlighting or dissing the competition. Mere microseconds after reading Claus Mikkelsen’s blog on the USP-V SPC figures, there are posts from...

October 3rd, 2007 | Uncategorized | Read More

PSSST….Green Storage

HDS announced today a few amendments to the AMS/WMS range. The most interesting is the apparent ability to power down drives which are not in use a-la-Copan. According to the press release above, the drives can be powered down by the user as necessary, which presents some interesting questions. Firstly,...

September 24th, 2007 | Uncategorized | Read More

NTFS Update

I did some more work on my NTFS issue on Friday. As previously mentioned, I was seeing NTFS filesystems with large levels of fragmentation even after drives were compressed. The answer turns out to be quite simple; Windows doesn’t consolidate the free space blocks which accumulate as files are...

September 24th, 2007 | Uncategorized | Read More

Pause for Thoughtput

I’ve just read a couple of Gary O’s postings over at Thoughtput, the blog from Gear6. In his article “Feeding the Virtual Machines”, he discussed NAS and SAN deployment for a virtual environment and makes the bold claim: “Most people tend to agree that NAS is easier and...

September 15th, 2007 | Uncategorized | Read More

DMX-4 Green or not?

After the recent EMC announcements on DMX-4, I promised I would look at the question of whether the new DMX-4 is really as green as it claims to be. I did some research and the results are quite interesting. Firstly we need to set the boundaries. One of the hardest part of comparing hardware from different...

July 20th, 2007 | Uncategorized | Read More

Performance Part V

Here’s the last of the performance measurements for now. Logical Disk Performance – monitoring of LDEVs. There are three main groups Tuning Manager can monitor; IOPS, throughput (transfer) and response time. The first two are specific to particular environments and the levels for those...

July 17th, 2007 | Uncategorized | Read More

Performance Part III

Next under discussion for performance is array groups. First the background (and as usual, apologies to those who already know all this). HDS enterprise arrays lay their disks out in array groups, either RAID-1/0, RAID-5 and RAID-6. Variable size LUNs are then carved out of the array groups for presentation...

July 9th, 2007 | Uncategorized | Read More

Using Tuning Manager for something useful – Part I

Stephen commented about Tuning Manager and doing something useful with the data. I thought I would use this as an opportunity to highlight some of the things I look at on a regular basis (almost daily, including today in fact). Part I – Write Pending. First a little bit of background; Write Pending...

June 26th, 2007 | Uncategorized | Read More

Posts Tagged ‘performance’