james <[email protected]> writes:
> On Tuesday 15 June 2010 10:00:03 [email protected] wrote:
>
>> > I am a PCLinuxos user and I have seen references to LVM here ( at SLUG) I
>> > have 3 drives LVM'd to give me 1.3TB of storage space on my server. The
>> > first drive of this set has died.
>>
>> I am guessing that by "LVM'd" you mean "concatenated together, no
>> redundancy", right? So, basically, you lost one disk and you have lost
>> (more or less) a third of the data under the file system, etc.
>
> The stuff below is interesting and a reference, but this highlights my
> favourite rant: Seagate's 'ATA more than an interface' says multiple disks
> in a machine *will* result in a higher failure rate, maybe much higher.
Without needing reference to a vendor study, you can work this out yourself
with some very basic probability math, and the MTBF values from the hard
disks.
Er, and watch out that things like bad batches of disks can result in failures
that are *not* "independent events" in probability terms.
> So raid is a less worse option than LVM.
They serve entirely different purposes, and have some cross-over; you would
see the same problem with a RAID0, or RAID-concatenated-space system as with
an LVM concatenated space system — or the same redundancy if you used the
LVM/DM RAID1 target as if you used the MD version of the same.
So, it isn't as simple as saying "RAID is better than LVM" without talking
about the additional details.
(...and, FWIW, my preference is *both* RAID and LVM. :)
Daniel
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