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Displaying posts with tag: hdd (reset)

Storage caching options in Linux 3.9 kernel
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dm-cache is (albeit still classified “experimental”) is in the just released Linux 3.9 kernel. It deals with generic block devices and uses the device mapper framework. While there have been a few other similar tools flying around, since this one has been adopted into the kernel it looks like this will be the one that you’ll be seeing the most in to the future. It saves sysadmins the hassle of compiling extra stuff for a system.

A typical use is for an SSD to cache a HDD. Similar to a battery backed RAID controller, the objective is to insulate the application from latency caused by the mechanical device, the most laggy part of which is seek time …

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On SSDs – Lifespans, Health Measurement and RAID
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Solid State Drive (SSD) have made it big and have made their way not only in desktop computing but also in mission-critical servers. SSDs have proved to be a break-through in IO performance and leave HDD far far behind in terms of Random IO performance. Random IO is what most of the database administrators would be concerned about as that is 90% of the IO pattern visible on database servers like MySQL. I have found Intel 520-series and Intel 910-series to be quite popular and they do give very good numbers in terms of Random IOPS. However, its not just …

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Green HDs and RAID Arrays
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Some so-called “Green” harddisks don’t like being in a RAID array. These are primarily SATA drives, and they gain their green credentials by being able reduce their RPM when not in use, as well as other aggressive power management trickery. That’s all cool and in a way desirable – we want our hardware to use less power whenever possible! – but the time it takes some drives to “wake up” again is longer than a RAID setup is willing to tolerate.

First of all, you may wonder why I bother with SATA disks at all for RAID. I’ve written about this before, but they simply deliver plenty for much less money. Higher RPM doesn’t necessarily help you for a …

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Tables on SSD, Redo/Binlog/SYSTEM-tablespace on HDD
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I recently did a disk bound DBT-2 benchmarking on SSD/HDD (MySQL 5.4.0, InnoDB). Now I'm pretty confident that storing tables on SSD, redo/Binlog/SYSTEM-tablespace on HDD will be one of the best practices for the time being.

This post is a detailed benchmarking report.
(This post is very long and focusing on InnoDB only. If you are familiar with HDD/SSD/InnoDB architecture and understand what my blog title means, skipping section 1 (general theory) then reading from section 2 (benchmarking results) would be fine. )

1. General Theory of HDD, SSD and InnoDB

SSD is often called as a disruptive …






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SeaTools for DOS v1.0PH – Overtemp–253
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I was running a hard drive diagnostic using SeaTools for DOS v1.09PH on two exactly the same Maxtor hard drives, see details of the drives below. When I attempted to run a quick scan and then a long scan it received a warning “Overtemp–253″. After doing some research I have come to the conclusion that with certainty that this doesn’t mean the hard drive is running at 253 degrees Fahrenheit. My two drives are well ventilated and do not even feel warm to the touch. In fact this message apparently means according to Seagate that the hard drive does not support SeaTools reading temperatures.

  • Brand: Maxtor
  • Model: …
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