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9

These raids are all relative to each-other assuming the same disks and controller in the array. Raid5: Good read speed, rotten write speed, can survive any double disk failure if the failures occur over enough time for the raid to rebuild between failures. (ie disk fails, raid rebuilds, disk fails, you're okay). If you have simultaneous double disk ...


9

There's lots of similar questions/arguments on this site regarding R10 vs. R5/R6 but they boil down to "exposure during rebuild". The argument for R10 over R5 is strongest when dealing with the larger, slower disks some buy because their GB/$£€ is better (i.e. 2/3TB 7.2k SATAs) as arrays of these disks can take literally days to rebuild following a disk ...


9

Whoever told you that RAID 10 is somehow inherently slower than RAID 1 doesn't know what they're talking about. That makes the rest of the question unanswerable as it's based on a false assumption. Further reading: What are the different widely used RAID levels and when should I consider them?


9

LXC/Docker by design doesn't have anything to do with RAID (any RAID) at all. Docker/LXC containers are run on the same kernel as the host. As such I don't think there are any docker related problems.


8

Each drive adds its performance to the sum, so more drives will be faster than less drives, all else being equal. The size doesn't directly have an effect, though. If you have a choice between 2.5 inch 300GB 10k RPM drives and 2.5 inch 900GB 10k RPM drives, they'll perform about the same, drive for drive. The difference is when you figure it per TB. So 10 TB ...


8

It's 10 (1+0), rather than 0+1 - because mirrored stripes are more likely to handle multiple disk failures than striped mirrors.


7

You may have misunderstood someone. RAID-5 is slower than RAID-10 on writes, but RAID-1 can be treated as a RAID-10 with a single pair of disks, and thus has the same performance per "spindle" as RAID-10. The best recommendation for SSD on a database is to use RAID-5. The rebuild time on the incredibly small and fast SSD drives is very good. Since you'll ...


7

RAID10 with 4 drives will be quicker -- the extra spindles mean that twice as many IOPS can be handled (more or less).


7

Each drive can do 180 random IOPs. Is your workload totally random? I bet what you're seeing is sequential reads/writes.


6

Yes, this will work. Of course, don't expect to get any performance gain as the underlying disks are on the same device, but it's a great way to learn how to set it up in a safe environment.


6

Your Volume Group isn't using the entirety of the extents created for it: VG Size 149.94 GiB PE Size 64.00 MiB Total PE 2399 Alloc PE / Size 1171 / 73.19 GiB Free PE / Size 1228 / 76.75 GiB You can add more extents using the following command: lvextend -l +100%FREE /dev/mongodb_vg/mongodb_lv /dev/md0 ...


6

The exact number, or even a reasonable estimate, would be impossible to guess based on this information. Many server grade disks have published number; but the RAID system may or may not take full advantage of the disks. The RAID HBAs generally also have some published benchmarks. Extrapolating from these is the best guess you'll get without testing an ...


6

As Chopper said, a striped data format will make it slightly less convenient to recover data from your drives. If you're RMAing the drives, you absolutely cannot count on any sort of wipe operation to do much good, since the most likely failure mode prevents you from reliably writing to some sectors, and the other failure mode prevents you from verifying ...


6

It makes no sense no, R10 would be better, but you should really try to have enough real memory to not have to care.


6

With SSD's the only generic recommendation is to buy the right drive for your workload. See this answer for the rationale. The warranty for the Samsung SSD 850 Pro may be ten years, but that covers mechanical failures and does not cover you when you exceed the still "somewhat limited" total write capacity limit. Associated with the failure rates and ...


6

You can't use non-HP SSDs in HP ProLiant servers like this. Just because this worked on your G7 server doesn't mean it is okay for your Gen8 ProLiant servers. (basically, why buy enterprise gear, then cripple it with incompatible components?) Please see: 3rd party SSD drives in HP Proliant server - monitoring drive health or Third-party SSD solutions ...


5

I am going to try and sum up my comments into an answer. The basic line is: You should not tinker with the strip size unless you have good evidence that it will benefit your workload. Reasoning: For striping, you have to choose some strip size and 64 KB is the default the manufacturer has chosen. As the manufacturer (LSI in this case, rebranded by Dell) ...


5

If RAID 1 was just hotwiring a cable the performance impact would be null (a factor of 1.0), but RAID 1 mirroring is more than just hotwiring a cable - actual work needs to be done to write data to two drives and handle the results of that write from each drive. That extra work is the factor they're talking about in the performance impact. Whether the I/O ...


5

I don't think so. Desktop versions of Windows will only support RAID-0 in software, mainly for applications like editing streaming media. Windows 2003 (and IIRC 2008) will support RAID-1 and RAID-5 in sofware but not RAID-10. Note that Software RAID support in Windows is generally poor - much poorer than that found in Unix or Linux. You are much better ...


5

I believe RAID10 support (through the fancy all-in-one RAID10 driver rather than doing a RAID0 of RAID1s) is not present in the installer for Etch or Lenny, but it has been added for the current development version so will be in the next release (or available now if you don't mind using the testing distribution, but this is not recommended in a production ...


5

I'd have to disagree with CHopper3. Since there are only 4 drives in this situation your failure capabilities are the same (2 drives) with either scenario, except with raid 10 if you happen to lose the wrong 2 drives then you'll have a real problem. Also there is definitely an added benefit of having a global spare for your other RAIDs as well.


5

I would go 10/2. Logs are usally small and sequential, and your RAID controller should be able to queue them efficiently enough to write them onto 2 disks in raid 1 without disturbing the rest. If your RAID controller can't do this then forget about any split and just go 12 if you are in a hurry. If you've got time run some tests and see what works. ...


5

I got explanation from guys on VMWare forum in thread http://communities.vmware.com/message/2012333 . And the reason is that ESXi does no caching and completely relies on the controller for writing data to disks so speed 20MB/s with write-through cache mode (only mode this controller supports as it does not have BBU) is standard. Hyper-V is apparently doing ...


5

RAID 6 or RAID 10. RAID 10 is a bit of a capacity waste, and RAID 6's random write penalty is completely hidden behind the write cache. I know you only think you'll need 4TB, but there's no reason to waste.


4

I would assume it is caching. You said write cache is disabled, but I see the "Array accelerator cache", I'm not familiar with that - but memory caching would explain bursts of high throughput.


4

First off all, see this post: What are the different widely used RAID levels and when should I consider them Notice the difference between RAID 10 and RAID 01. Match this to your setups (both of them labeled as RAID 10 in your text). Look carefully. Read the part in the link I posted where it states: RAID 01 Good when: never Bad when: always ...


4

The second configuration is what you want. Multiple RAID1 mirrors striped together. I don't understand why some controllers give people non-viable options.


4

Windows software RAID doesn't support RAID-10. I've never heard of third-party drivers for Windows software RAID and, frankly, I think I'd be afraid of them if they did exist. (They'd have to be debugged and battle-tested before I'd even think of using them...)


4

Just use one bit 6-way RAID10 array per server, it's kind of pointless doing anything else as you're using such slow drives and you'll lose some IO performance due to virtualisation anyway (you didn't mention hypervisor or disk access method by the way).


4

First of all hdparm is not a real benchmarking utility, it isn't nearly rigorous enough to demonstrate true performance. Better tools are iozone or iometer. Secondly, your results can be explained with one observation. Number of disks matters. Consider this: Your R0 test had 6 disks involved in reading. Your R1 test had 1 disk involved in reading. ...



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