[cisco-voip] UCS C210 Replace 146 GB Disk in RAID5 with 300 GB Disk

[Lelio Fulgenzi]

The idea of RAID drives and managing the different volumes always had me on the fence on how to do things. In a perfect world, I’d stick with one big RAID 6 array with a spare on the shelf.

The BE7K servers I ordered were delivered with 4 RAID 5 arrays. Personally, while I can appreciate separating the arrays, I don’t like losing that extra space and managing which volume to put images on is a pain.

I’ll admit, I looked at RAID 10 (when I was first reading the TRC specs) and was confused to heck. I did finally understand things after referring to a colleague, but it was a lot of drawing out.

I will say this, RAID isn’t gonna protect you if you don’t have platform monitoring on. You need to know the second a drive fails so you can proceed accordingly.

Also, if the ever do construction in your computer room, do yourself a favour, go to the hardware store, buy a 9.99 loose fibre furnace filter and stick it in front of your air intakes.



From: cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] On Behalf Of Charles Goldsmith
Sent: Tuesday, November 14, 2017 9:48 AM
To: Ryan Huff <ryanhuff at outlook.com>
Cc: cisco-voip at puck.nether.net
Subject: Re: [cisco-voip] UCS C210 Replace 146 GB Disk in RAID5 with 300 GB Disk

I've seen one URE fail in a raid 5 resilvering process, years ago on a DG system.  Had to rebuild and restore from backup, fun times.

I agree Ryan, on a TRC system and RMA a drive, you stick with it.

From my reading on TRC, you can rebuild as a RAID 10 and get faster speeds, but you lose some space in the process.

On my personal systems, I'm using RAID 10 everywhere.

On Tue, Nov 14, 2017 at 8:17 AM, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>> wrote:
As I’ve read and understood; it isn’t due to actual functionality though. It is as you say, due mostly to longer rebuild times (indexing a physically larger geometry than the rest of the array members, for a smaller logical geometry) and the risk (rare IMO) to the rest of the array (as a rebuild will stress the array and could cause other, near-death disks to fail thereby causing the array to fail). It also wastes the extra horsepower of the disk since the existing RAID can’t capitalize on the resources of the larger disk.

So in a case of, would you go out and buy a new disk that way .... I’d say no; but if that is the result of a covered RMA, I’d say go for it.

I’m no diskologist though ... just based on my own experiences of what has worked for me for the last couple of decades ... and I’ve never lost a server ... outside of that one time when my pants pocket snagged the release on the 2nd disk in a R5 on my way out the door ... bad memories.
-Ryan

On Nov 14, 2017, at 9:03 AM, Charles Goldsmith <wokka at justfamily.org<mailto:wokka at justfamily.org>> wrote:
Keep in mind, RAID 5 is ok for smaller disks, but larger disks it's no longer recommended, but sadly, the best article about it is from Dell: http://en.community.dell.com/techcenter/b/techcenter/archive/2012/08/14/new-equallogic-raid-tech-report-considerations-and-best-practices-released

With bigger disks, it's even said that RAID 6 is no longer good enough, due to large rebuild times in case of a failure.  http://www.zdnet.com/blog/storage/why-raid-6-stops-working-in-2019/805

On Tue, Nov 14, 2017 at 7:41 AM, Ryan Huff <ryanhuff at outlook.com<mailto:ryanhuff at outlook.com>> wrote:
Reto,
Seek/rpm speeds and media type (flash, sata ... etc) are usually what matter the most for RAID disks. If your only difference is total storage capacity, the bigger disk will usually work just fine, your just gonna waste the additional 154GB of space (because the RAID will only provision 146GB of that 300GB disk).

Just remember on a RAID 5, don’t pull/lose more that 1 disk at a time .... painful lesson long ago I share over beer every now and then.

-Ryan

On Nov 14, 2017, at 8:23 AM, Reto Gassmann <voip at mrga.ch<mailto:voip at mrga.ch>> wrote:
Hallo

We have a UCS C210 Server with 10x146 GB Disks. One of the Disks failed and I got a 300 GB replacement Disk from Cisco.

Is that a problem if I replace the defect 146 Disk in the RAID 5 with a 300 GB Disk?

Thanks for help
Regards Reto
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