> > 0.90. Every server has a Raid-5 array consisting of 5 large IBM
> scsi disks +
> > one spare. It works like a charm, extremely fast and no trouble
> at all with
>
> How fast are the IBM disks? We're using Quantums here and they suck!
I haven't done any actual, documented testing, but they're the fastest SCSI
disks that IBM got. I don't have access to the exact modelnumbers right now
since I'm not on site, but I believe they have a 2Mb cache and use LVD
technology w/ SCSI-UW2 on AIC7890. The machines work mainly as
web/mailservers with a lot of dynamic content, so there's a lot of disk
activity going on, and my experience is that the RAID5 arrays are Very Very
Fast. We have some 50 disks from IBM, and have experienced hardware failure
on 2, I think that's pretty normal. With RAID5 and an extra disk in each
array, these disk failures are not a big problem.
> > disturbing lines on one of the consoles:
> > raid5: bug: stripe->bh_new[4], sector 8419312 exists
> How many lines showed up? And did this go on for a while?
Only four. I got a very nice reply from Gadi, basically explaining that this
is nothing to worry about. Drop me a note if you want to read it, it's a
little lengthy so I'm refraining from mailing it to the list without being
asked to. Makes good reading though.
The machine has continued to work without any problems. We generally have
uptimes > 1 month, and have not had any stability problems related to
software (Linux, RAID etc) for many months. This is under pretty heavy load
with some 1200 - 1500 users on each box.
We used to experience soft-reboots every 8-10 days or so, but when I
increased the maximum number of allowed tasks and the number of tasks
reserved for root, this problem disappeared:
(from linux/tasks.h:
#define NR_TASKS 2048
...
#define MIN_TASKS_LEFT_FOR_ROOT 32
)
Regards,
/Johan Ekenberg
