Re: HD from different manufacturers in a RAID 5

"Robert Heller" <heller@xxxxxxxxxxxx> wrote in message news:10d4c$46657c7f$404a99a1$19278@xxxxxxxxxxxxxxxxxxxxx
At Tue, 05 Jun 2007 13:52:11 -0000 Al <bernala@xxxxxxxxx> wrote:


The latest discussion on this topic I could find in over 4 years old,
so I hope to get some new opinions. I have a RAID 5 array composed of
3 Maxtor Atlas 10K IV 36GB U320 SCA 80-PIN LVD Hard Drives. My RAID
controller is an IBM serveRAID 4Mx. everything is working great.
Normally, we keep spare drives in case one should ever fail, so we can
pull it off the shelf and immediately replace the failed drive.

Unfortunately, Maxtor drives are no longer manufactured, ever since
they were bought out by Seagate.

Doesn't necessarily mean they aren't available anymore.

We're running low on spares, and I
want to get some more. I called SeaGate and asked them what drive
matches these specs, and they told me the Chetah 36GB (P/N ST336607LC)
is a perfect match. When I asked if there were any compatibility
issues considering it will go into an existing RAID 5 array made up of
Maxtor drives, I was told "there *shouldn't* be any." Well, I don't
want to take his word for it,

he's a salesman - not a RAID expert.

Since when can a salesman not be a RAID expert?


Can someone give me some specific pointers on what to check so I can
be as sure as possible this will work? Or would you recommend I
replace all 3 Maxtors with Cheetah drives? I am quite new to RAID, so
please assume I am an idiot on the subject. Thanks.

Al

Below is the status of a perfectly working RAID-5 system, with 6 IBM
148gig and 2 Fujitsu 148gig drives, all but one bundled into a RAID-5
array (one of the Fujitsu is a 'hot spare' (Standby) drive). So yes,
the salesman is correct. The controller should not care about the 'vendor',

So Heller, where exactly does it say serveRAID 4Mx in there, below.

so long as the the block count matches. At *worst* if the new disks are
a few blocks larger, it might just not use the extra blocks.

Wrong Heller, at worst is when the new disks are a few blocks smaller.
Atlas typically has 71,833,095 sectors, Cheetah 71,687,372 sectors.

I would just stock up on a few Cheetah drives and replace the Maxtors
as they fail,

Yeah that might be a good time to figure out *why* it doesn't work *when*
it doesn't work.

unless the Maxtors are close to EOL (how old are they?).

***** DAC960 RAID Driver Version 2.4.11 of 11 October 2001 *****
Copyright 1998-2001 by Leonard N. Zubkoff <lnz@xxxxxxxxxxxxx>
Configuring Mylex DAC1164P PCI RAID Controller
Firmware Version: 5.08-0-87, Channels: 2, Memory Size: 32MB
PCI Bus: 6, Device: 8, Function: 0, I/O Address: Unassigned
PCI Address: 0xFDBFFC00 mapped at 0xF8844C00, IRQ Channel: 48
Controller Queue Depth: 128, Maximum Blocks per Command: 128
Driver Queue Depth: 127, Scatter/Gather Limit: 33 of 33 Segments
Stripe Size: 64KB, Segment Size: 8KB, BIOS Geometry: 255/63
SAF-TE Enclosure Management Enabled
Physical Devices:
0:0 Vendor: FUJITSU Model: MAP3147NC Revision: 5608
Serial Number: UP36P3900F2V
Disk Status: Online, 286748672 blocks
0:1 Vendor: FUJITSU Model: MAP3147NC Revision: 5608
Serial Number: UP36P3900F85
Disk Status: Standby, 286748672 blocks
0:6 Vendor: PE/PV Model: 1x2 SCSI BP Revision: 1.1
0:7 Vendor: MYLEX Model: DAC1164P Revision: 0508
Serial Number:
1:0 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVDW91C
Disk Status: Online, 286748672 blocks
1:1 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVDAJ6C
Disk Status: Online, 286748672 blocks
1:2 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVD96NC
Disk Status: Online, 286748672 blocks
1:3 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVE7T7C
Disk Status: Online, 286748672 blocks
1:4 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVBZNXC
Disk Status: Online, 286748672 blocks
1:5 Vendor: IBM Model: IC35L146UCDY10-0 Revision: S27F
Serial Number: ECVE7HWC
Disk Status: Online, 286748672 blocks
1:6 Vendor: PE/PV Model: 1x6 SCSI BP Revision: 1.1
1:7 Vendor: MYLEX Model: DAC1164P Revision: 0508
Serial Number:
Logical Drives:
/dev/rd/c0d0: RAID-5, Online, 37748736 blocks, Write Thru
/dev/rd/c0d1: RAID-5, Online, 1682743296 blocks, Write Thru
No Rebuild or Consistency Check in Progress
.

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