Didn't realize you set a chunk size on an LVM, thought that was a hardware RAID only feature. I would think the chunk size would be dependent on the number of drives in the stripe and The average size of a record in the database.
When I setup our RAID array, I went with the default chunk size, but did have the option to Reduce it if I wanted to, but chose not to, since the speed was pretty good (15K SAS drives) George -----Original Message----- From: u2-users-boun...@listserver.u2ug.org [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Wols Lists Sent: Monday, November 28, 2011 4:37 PM To: u2-users@listserver.u2ug.org Subject: Re: [U2] Question about lvm stipe size - What block size does UV write in? On 28/11/11 18:15, John Thompson wrote: > So I'm setting up a lvm striping plus mirrorring configuration with 4 disks > to use for a Universe database in Linux. > > And I'm curious, what block size does UV write in? > > Is it 4k blocks? Less or more than that? By default, iirc, it's 4K. INFORMATION was 2K. But why should that matter as far as your RAID is concerned? > > As far as lvm or raid, what stripe sizes are your RAID arrays or LVM > volumes set to? 64k? And what size does your DISKS have their buffers set to? I think the modern default is 4 *meg*. > > Our current machine is set to 64K, but, I was just curious if there is some > recommended size to use. > I am referring to a stripe size in a RAID array or lvm logical volume. > Can't give you any advice, unfortunately, other than to say it's complicated, and you probably need a specialist. If you're running licenced RHEL, I'd get Red Hat to advise. My instinct would be to go for whatever the disk buffers are, but I think that's the wrong choice... Cheers, Wol _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users
