NETGEAR is aware of a growing number of phone and online scams. To learn how to stay safe click here.
Forum Discussion
Solved
Is my hard drive toast? Massive Current Pending Sector count + sluggish performance of ReadyNAS.
Morning, I have a ReadyNAS Ultra 2 running RAIDiator 4.2.27 using RAID Level 1. As well as providing storage for a lot of media, It was also being used as a Time Machine backup from my macbook a...
ChunkySocks wrote:
Morning,
I have a ReadyNAS Ultra 2 running RAIDiator 4.2.27 using RAID Level 1.
As well as providing storage for a lot of media, It was also being used as a Time Machine backup from my macbook and I noticed that the time taken for a backup to complete greatly lengthened nearly two weeks ago. So checking the logs, I have the first appearance of this message:
Detected increasing pending sector count[65535] on disk 2 [WDC WD30EZRX-00MMMB0, WD-WCAWZ1421563]. This often indicates an impending failure. Please be prepared to replace this disk to maintain data redundancy.
on Oct.10 with further instances after, although not every day and with the number decreasing albeit by very little (latest log error message has the figure at 65515). Checking this thread on the NETGEAR forums and running SMART, the Reallocated Sector Count is zero.
My questions are:
- since the HDD isn't even able to remap the sector, it's a goner isn't it?
Any drive with 65515 pending+reallocated sectors is a goner.
If a disk error occurs on a write, then the sector is reallocated/remapped - because the drive knows what to put there.
But if the disk error occurs on a read, then then the drive doesn't reallocate - simply because it has no idea what data it should write there. So instead it increments the "pending sector" count.
- I have already ordered a replacement - is it best practice with a NAS to have two HDD that are exactly the same make if possible? The two 3TB HDDs currently in the ReadyNAS are WD Caviar Green (WD30EZRX), the replacement will be a 3TB WD Green (WD30EURS); I guess as long as both HDDs are of the same capacity, it doesn't matter.
You don't need to match drive models, only capacity. However a WD30EFRX (WDC Red) would have been a better choice. It is intended for NAS use, the WD Green is not. The Red also has a longer warranty.
- is the slow and sluggish performance of my ReadyNAS a result of the problems with disk 2 in my array as it continually attempts to re-write or remap the bad sectors without success?
As noted above, the drive is not re-writing or re-allocating anything. But it will retry the reads after they fail, and that will kill performance. Also, the failed reads are requiring RAID recovery (e.g., re-reading from the mirrored drive).
- lastly, when I've got my replacement drive, is it simply a matter of swapping the HDD in the disk 2 bay and it ought to just start copying all the data across from disk 1?
Yes. Just remove the failing drive, put the replacement into the tray, and reinsert (all with the NAS running).
Though I usually run WDC Lifeguard on the new drive first.
It's a good idea to update your backups before you swap disks or update firmware. You might do that while you are waiting for your new drive.
ChunkySocks wrote:
Morning,
I have a ReadyNAS Ultra 2 running RAIDiator 4.2.27 using RAID Level 1.
As well as providing storage for a lot of media, It was also being used as a Time Machine backup from my macbook and I noticed that the time taken for a backup to complete greatly lengthened nearly two weeks ago. So checking the logs, I have the first appearance of this message:
Detected increasing pending sector count[65535] on disk 2 [WDC WD30EZRX-00MMMB0, WD-WCAWZ1421563]. This often indicates an impending failure. Please be prepared to replace this disk to maintain data redundancy.
on Oct.10 with further instances after, although not every day and with the number decreasing albeit by very little (latest log error message has the figure at 65515). Checking this thread on the NETGEAR forums and running SMART, the Reallocated Sector Count is zero.
My questions are:
- since the HDD isn't even able to remap the sector, it's a goner isn't it?
Any drive with 65515 pending+reallocated sectors is a goner.
If a disk error occurs on a write, then the sector is reallocated/remapped - because the drive knows what to put there.
But if the disk error occurs on a read, then then the drive doesn't reallocate - simply because it has no idea what data it should write there. So instead it increments the "pending sector" count.
- I have already ordered a replacement - is it best practice with a NAS to have two HDD that are exactly the same make if possible? The two 3TB HDDs currently in the ReadyNAS are WD Caviar Green (WD30EZRX), the replacement will be a 3TB WD Green (WD30EURS); I guess as long as both HDDs are of the same capacity, it doesn't matter.
You don't need to match drive models, only capacity. However a WD30EFRX (WDC Red) would have been a better choice. It is intended for NAS use, the WD Green is not. The Red also has a longer warranty.
- is the slow and sluggish performance of my ReadyNAS a result of the problems with disk 2 in my array as it continually attempts to re-write or remap the bad sectors without success?
As noted above, the drive is not re-writing or re-allocating anything. But it will retry the reads after they fail, and that will kill performance. Also, the failed reads are requiring RAID recovery (e.g., re-reading from the mirrored drive).
- lastly, when I've got my replacement drive, is it simply a matter of swapping the HDD in the disk 2 bay and it ought to just start copying all the data across from disk 1?
Yes. Just remove the failing drive, put the replacement into the tray, and reinsert (all with the NAS running).
Though I usually run WDC Lifeguard on the new drive first.
It's a good idea to update your backups before you swap disks or update firmware. You might do that while you are waiting for your new drive.
Thanks for taking the time to reply & explain StephenB.
I did see that WD Red were for optimised for NAS use and was searching for one at a good price but this sealed GreenPower one came up first - I'm not buying new new (unfortunately I'm too broke) and thought that the WD Green range were optimised for an economical power and performance but I'll consider buying Red going forwards.
If I wanted to run WDC Lifeguard, how would I do it since the ReadyNAS is the only kit I use that takes 3.5" drives as my main and only machine is a macbook? Don't worry, no need to answer this if you're only illustrating what you would do in an ideal scenario.
RAIDiator 4.2.27 is the latest (last?) firmware for my ReadyNAS if I understand correctly, by revisiting the revamped forums, I've just discovered that it's possible to upgrade my Ultra 2 to OS 6 which is something that I'm willing to try when I have the time. It raises some other questions that I'll post separately but will also see if they're answered in OS6 now works on x86 Legacy WARNING: NO NTGR SUPPORT! thread.
ChunkySocks wrote:
If I wanted to run WDC Lifeguard, how would I do it since the ReadyNAS is the only kit I use that takes 3.5" drives as my main and only machine is a macbook?
Unfortunately you can't. There likely are other diags you could use on a macbook, but since I only use windows systems I have no recommendations there.
So you'll have to assume that the drive is ok. The NAS will run a short SMART test before it uses the drive - not as good as the long test, but still a useful check.
NETGEAR Academy
Boost your skills with the Netgear Academy - Get trained, certified and stay ahead with the latest Netgear technology!
Join Us!
