Just for fun, I tried updating the firmware so that our existing SCSI card would support mirroring. That did not work, so hardware RAID is off the table for now.
In this case, given the limitations of the card, hardware RAID would have been less desirable anyway, perhaps, because the card only supports 0 and 1, not 5. This would limit us to 36GB of disk space.
With software RAID, we can do RAID 5, so that our 3x36 can work as 72GB.
So, I think that's what we should do.
--Jimbo
On Tue, 03 Feb 2004 10:38:00 -0800, Jimmy Wales wrote:
So, I think that's what we should do.
When will the replacement controller arrive? If it's adding a day or so delay it's propably not worth to bother setting up the soft raid now. Should be possible to get one overnight really- i can send stuff from Germany to any place in the US overnight, likely to work inside the US as well.
O.k., well, yesterday the other fellow yelled at me (not really) that I should be doing software RAID anyway. I *can* get anything overnighted to me, to be sure. Should I?
Possibly that's the wisest thing to do here.
Gabriel Wicke wrote:
On Tue, 03 Feb 2004 10:38:00 -0800, Jimmy Wales wrote:
So, I think that's what we should do.
When will the replacement controller arrive? If it's adding a day or so delay it's propably not worth to bother setting up the soft raid now. Should be possible to get one overnight really- i can send stuff from Germany to any place in the US overnight, likely to work inside the US as well. -- Gabriel Wicke
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Well, software RAID may be faster for long, sequential writing and reading, but we don't have very much data going in or out. Some typical numbers may be 2-3MB/s read and ½-1 MB/s write. The parity calculation on that is going to be negligible, no matter what solution we choose. The problem is of course that this data is spread all over the disk, so seek time is the major bottleneck. I do not know if the performance hw/sw RAIDs differ significantly in this aspect. With the average RAID card, replacing a faulty HDD is as simple and error prone as, well, replacing a HDD when the warning e-mail drops in your inbox. I'd say that's hard to beat as far as data security goes.
// E23
Jimmy Wales jwales-at-bomis.com |wikipedia| wrote:
O.k., well, yesterday the other fellow yelled at me (not really) that I should be doing software RAID anyway. I *can* get anything overnighted to me, to be sure. Should I?
Possibly that's the wisest thing to do here.
Gabriel Wicke wrote:
On Tue, 03 Feb 2004 10:38:00 -0800, Jimmy Wales wrote:
So, I think that's what we should do.
When will the replacement controller arrive? If it's adding a day or so delay it's propably not worth to bother setting up the soft raid now. Should be possible to get one overnight really- i can send stuff from Germany to any place in the US overnight, likely to work inside the US as well. -- Gabriel Wicke
On Tue, 3 Feb 2004 14:00:58 -0800, Jimmy Wales jwales@bomis.com wrote:
O.k., well, yesterday the other fellow yelled at me (not really) that I should be doing software RAID anyway. I *can* get anything overnighted to me, to be sure. Should I?
I use software RAID 5 with a 2.4 kernel, and with a 4+1 120GB setup (468GB total usable). My experiences have been mixed: nothing patently bad, but I wouldn't exactly call it a smooth ride, either. If you can go for the hardware controller without too much hassle, go for it.
Best regards, Ivan
Gabriel Wicke wrote:
When will the replacement controller arrive? If it's adding a day or so delay it's propably not worth to bother setting up the soft raid now. Should be possible to get one overnight really- i can send stuff from Germany to any place in the US overnight, likely to work inside the US as well.
I have ordered a RAID card for overnight delivery. Since it is evening now I am not sure if that means tomorrow, or the next day. Depends on whether the merchant can it get in the hands of FedEx in time or not.
Either way, I think it's safe to assume that we'll have it in place by Thursday evening.
Where do we stand on going live with a 'beta'? Is there anything that I can do to help co-ordinate?
--Jimbo
"JW" == Jimmy Wales jwales@bomis.com writes:
JW> With software RAID, we can do RAID 5, so that our 3x36 can JW> work as 72GB.
JW> So, I think that's what we should do.
A couple of things:
* Software RAID in Linux is notoriously bad for disk I/O. * It's also surprisingly intolerant of bad blocks on drives. This shouldn't normally be a problem, but it can be a problem if more than one drive in the set has a bad block (not that uncommon). My experience has been that if one drive fails, reassembling the RAID set can fail due to minor errors on the other drives.
EVMS (http://evms.sourceforge.net/) is a very nice enhancement for Linux volume management, and may be worth looking at. It's a hassle to set up (unless you're using Gentoo, which has it built-in), but it's got good buzz and might be helpful. It also has bad-block reallocation -- a nice feature.
~ESP
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