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Raid 5 guestions??
patrickl:
--- Quote from: squirrellydw on February 04, 2008, 10:35:33 am ---OK, a few more questions now.
What is JBOD
--- End quote ---
Not exactly what Boykster meant there, but it's 'Just a Bunch Of Disks'. Guess he means that the whole solution is always as strong as the weakest link. That's also why I'm not in favor of a non-redundant OS disk.
--- Quote ---What is considered an enterprise disk
--- End quote ---
Enterprise disks are designed to work in 24/7 applications. They have a higher MTBF rating (ie less likely to break) to offset the fact that they will be running a lot more in a 24/7 application than the 8/5 application of a desktop computer.
In the days of ATA (now called PATA) these only existed as SCSI disks, but these days you can buy them with a SATA or SAS interface.
Problem is that these disks are more expensive (quite a lot actually), but they should be better suited to the task. Google uses consumer grade disks though. Guess they don't think it's work the extra money.
For instance the Seagate Barracuda 7200.11 versus the Barracuda ES.2.
--- Quote ---what do you mean by spin down the drives
--- End quote ---
When there is no disk activity you can make the disks stop spinning. This saves power, reduces heat and can prolong the life of the drive (especially a consumer disk which is built to run during office hours only).
This is also one of these areas where you will hear different opinions. Mostly depending on how old the info that the person you talk to is using. In the past, disks had to keep on running all the time because starting them up could make the motor seize and ruin the drive. The same can still happen, but it's less likely these days.
Disks are actually rated for a number of spin-down/spin up cycles too.
BTW putting the OS on an array makes it about impossible to let array spin down since the OS often writes something to disk. Since you are not putting the OS on the array spinning down the disks is something you could consider.
:edit: spell disaster
squirrellydw:
Cool, I have both a 7200.11 and a ES drive. I never realized what the difference was.
boykster:
--- Quote from: patrickl on February 04, 2008, 11:45:47 am ---
--- Quote from: squirrellydw on February 04, 2008, 10:35:33 am ---OK, a few more questions now.
What is JBOD
--- End quote ---
Not exactly what Boykster meant there, but it's 'Just a Bunch Of Disks'. Guess he means that the whole solution is always as strong as the weakest link. That's also why I'm not in favor of a non-redundant OS disk.
--- End quote ---
[/quote]
That's what I was referring to, I guess saying 'a bunch of disks in JBOD' is redundant. I guess what I should have said was a bunch of disks in RAID0 spanning or just attached as individual drives. All data, no redundancy.
I agree on not considering MTBF an insurance policy, and on keeping packing materials for your drives. I now exclusively have been buying Seagate drives since they offer a 5 year warranty. I'm in the "don't spin down" camp, but there are valid arguments on both sides of the fence on that one.
patrickl:
--- Quote from: boykster on February 04, 2008, 02:25:53 pm ---I now exclusively have been buying Seagate drives since they offer a 5 year warranty.
--- End quote ---
Did you have to pay an administreation fee? I really hated that. I bought 4 Seagates. 2 of them failed within a few months and they wanted something like 50 euro administration fee.
A few months ago I sent some Maxtor drives back (to Seagate since they bought Maxtor) and I didn't have to pay.
--- Quote ---I'm in the "don't spin down" camp, but there are valid arguments on both sides of the fence on that one.
--- End quote ---
I'm on both sides and I use both depending on the situation.
Looking at the annual failure rates that Seagate reports for using a desktop drive 8/5 versus an enterprise disk used 24/7 shows that the enterprise drive is twice as likely to fail. So a drive with almost double the MTBF is still twice as likely to die when it is used 4 times as much. That shows that at least Seagate thinks that running the drive twice as many hours ages the drive twice as much. ie spinning it down will prolong the life.
At 8 Watt a drive with 5 drives that adds up to 40 Watt. It's not spectacular, but still.
On the other hand spinning down and up too often can kill the disk too.
Spinning a drive back up can take 15 seconds. It's annoying if you have to wait for that.
So on my webservers I don't spin down and my office file server does spin down.
boykster:
Nope, no fee in the US at least to RMA a seagate within the warranty period. You do have to pay return shipping for a tracked carrier and have to have proper packaging.
I generally go for an advance replacement that costs $19.99 but they ship the drive via 2-day delivery and include a pre-paid return shipping label with the required packaging.
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