[DRBD-user] Scsi timeout / sync rates / speed

Lars Ellenberg Lars.Ellenberg at linbit.com
Thu Sep 30 20:59:39 CEST 2004

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


/ 2004-09-30 13:56:05 -0400
\ Dan Didier:
> First some background on our systems.  They are both Dell 2400 with a
> built in raid controller with 64megs of memory.  The OS is on a separate
> mirrored RAID partition.  The data is a RAID 5 partition.  We are using
> 100mb Intel NICs for data sync.  Dual processor 733Mhz.  Both are
> running Redhat9 kernel 2.4.20-31.9smp.  DRBD 0.7.4
> 
> I have been watching our systems and have some questions that hopefully
> some of you can help with.
> My first question is what is the difference between speed and K/sec.  As
> you can see below the first output shows:
> finish: 26:02:30 speed: 508 (1,428) K/sec, while the second shows:
> finish: 1:17:08 speed: 10,632 (1,576) K/sec
                         ^ current `average since sync started
note that the "," marks the thousand, not the decimal point

> The K/sec is the same but the speed is much lower.  Is this because of
> disk write issues?

its only a rough guestimate anyways.

> On my secondary box I get the follwing in my dmesg:
> aacraid:ID(0:02:0) Timeout detected on cmd[0x2a]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)
> aacraid:ID(0:02:0) Timeout detected on cmd[0x2a]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)
> aacraid:ID(0:04:0) Timeout detected on cmd[0x28]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)
> aacraid:ID(0:03:0) Timeout detected on cmd[0x2a]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)
> aacraid:ID(0:04:0) Timeout detected on cmd[0x2a]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)
> aacraid:ID(0:02:0) Timeout detected on cmd[0x2a]
> aacraid:SCSI Channel[0]: Timeout Detected On 1 Command(s)

sorry. not drbds fault.
it only stresses your hardware more than your hardware seems to like.
this of course will bring down your performance big time.

> I have two identical boxes.  I have swapped the drives out to make sure
> this isn't a hardware issue.  This always occurs on the secondary which
> I suppose would make sense as that is where all the writes are occuring.

hm. maybe aacraid driver issue. dunno.


	Lars Ellenberg

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