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86036
October 16th, 2014 23:00
dealing with bad blocks using the Dell H700
I'm a Sysop trying to understand what's going on inside the datacenter. Our hosting manager tells me that the dell OSMA is reporting bad "virtual blocks" on some of our disks. From what I'm told, we are using a JBOD like configuration with the controller, where each virtual disk represents a single physical disk. No RAID striping or backups are taking place. Our data on the disks is recoverable from other hosts.
He is telling me that he would like to use the OSMA tool to reset the bad virtual blocks, and then to re-format the drives afterward. Is this a common practice? At what point to you give up on a disk, or are these drives already garbage when we first need to reset the bad virtual blocks?
DELL-Bo Pham
2 Intern
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261 Posts
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October 20th, 2014 08:00
Hello,
Normally, you let the system auto-correct the bad blocks that it finds and clear the Virtual Disk Bad Block message through OMSA accordingly. However, with all the disks running as RAID 0, it may not have the ability to correct the bad blocks that are affecting data since there are is parity to pull from other redundant drives. You should also export your controller log to determine if your Patrol Reads are reporting any issues. If you are on manual mode for Patrol Reads, then start a cycle to determine the extent of the damage.
Running a backup will help you determine if the data portion is affected by the bad blocks.
Otherwise, if it all looks goods then you may simply clear the message by choosing “Clear Virtual Disk Bad Blocks” from the VD options through OMSA.
For a full explanation, please refer to pages 232-234 and Table 13-2 of the users guide below:
ftp://ftp.dell.com/Manuals/all-products/esuprt_electronics/esuprt_software/esuprt_ent_sys_mgmt/dell-opnmang-srvr-admin-mngd-das_User's%20Guide_en-us.pdf
You also run the hardware diagnostics on the drives from the USC menu outside of the OS. Replace the drives as needed upon failure of the diags. Reformatting the drives will not resolve the issue.
Please let us this help moving in the right direction.
pcmeiners
6 Operator
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1.8K Posts
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October 20th, 2014 11:00
"Reformatting the drives will not resolve the issue" ....
As stated by Bo, reformatting will not help, especially high level formatting which OSs can do; unless you are the manufacturer, you do not have low level formatting ability, which could permanently mark/hide bad blocks .
If the number of bad blocks increases consistently over time on a drive, it is time for a new drive; e.g. Consistency Checks or Patrol reads produce new block errors most times they run.
If a few errors show up over a long period of time, just monitor the affected drive. It is not abnormal for a small number of defects to show up over time on drives. This type error could be from a minor manufacturing defect showing up or a rare speck of dust