User Manual
BC4000 Series RAID Controllers
02/13/06
B ro ad c om C o r p or at i on
Document
BC4000-UM100-R
Managing Controllers, Arrays, and Disks: bcadm --manage
Page 121
--cache-disk, -cd
The Cache Settings for Disks option sets the cache attributes for disks. If the disks support this option, you can
change read-ahead and write cache properties. The default settings are for both read and write caches (
rw
)
to be enabled. This option uses
--disk
as a qualifier.
--check-start, -cs
The Start Consistency Check option starts a consistency check on arrays, redundant types only. When you
select this option, you start the process of verifying that the parity (RAID5) or mirror drive consistency is correct.
If inconsistent areas are found, they are corrected during this process. Having consistent arrays is very
important when a drive fails. If an array is inconsistent and a drive fails, data will be lost.
If you do not use the
--no-sync
option when you create an array (see
“--no-sync, -ns” on page 131
), a
consistency check is performed when you create a redundant array type. While a consistency check during a
CREATE task can be removed, the array will not be redundant. Until a check is run from end to end, the array
will not be protected. After a check has been started, you can adjust the
Check Consistency task priority
relative to user I/O activity with the
--priority
option (see
“--priority <1...10>, -p <1...10>” on page 132
).
Caution!
Leaving write-back caching enabled may increase the likelihood of data being corrupted if
the system were to crash or lose power.
Long form:
--cache-disk <cache_attribute> --disk <list>
Short form:
-cd <cache_attribute> -a <list>
The cache attributes are:
r
rw
w
nc
read-ahead cache
read-ahead and write-back cache
write-back cache
no cache
Example 1:
bcadm --manage --cache-disk r --disk 1 2 3
Example 2:
bcadm -M -cd w -d *
Notes:
•
CHECK CONSISTENCY task can be started at any time on a redundant type array as long as
another task is not running on the array.
•
If an array goes critical during a Check Consistency, the check consistency will fail.
•
A CHECK CONSISTENCY task can be started while under I/O load.
•
For estimating how long the consistency check will take, a query on the array displays what
percentage of the task is complete.
