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Spontaneous Parity Checks?

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My unRAID server has been running reliably for a few months now, but I've noticed one quirky thing.  Twice it has initiated a parity check for no apparent reason.  The first time was completely spontaneous, or at least I couldn't think of any reason why it would do it.  Perhaps I pressed the 'check' button accidentally, but I doubt it.  The second time was just a few days ago.  There was a thunderstorm and my house lost power for a brief second, causing all my computers to shut down the bad way (I don't have a UPS, unfortunately).  When I booted the unRAID server back up, it immediately started a parity check.  If this is a built-in feature to make sure nothing was damaged due to the power loss, then that's understandable.

 

Has anyone else experienced this?  Is this supposed to happen, or should I be worried?

My unRAID server has been running reliably for a few months now, but I've noticed one quirky thing.  Twice it has initiated a parity check for no apparent reason.  The first time was completely spontaneous, or at least I couldn't think of any reason why it would do it.  Perhaps I pressed the 'check' button accidentally, but I doubt it.  The second time was just a few days ago.  There was a thunderstorm and my house lost power for a brief second, causing all my computers to shut down the bad way (I don't have a UPS, unfortunately).  When I booted the unRAID server back up, it immediately started a parity check.  If this is a built-in feature to make sure nothing was damaged due to the power loss, then that's understandable.

 

Has anyone else experienced this?  Is this supposed to happen, or should I be worried?

Perfectly normal after a non-clean shutdown.  It is supposed to happen. 

 

(It is also normal if you press the "Check" button)

 

Oh yes, even a small UPS will get you through the summer lightning storms and power blips.  I recommend an APC brand, as it is easy to interface to the unRAID server to have it cleanly shut down in an extended outage, and thus not require a parity check on re-start when power returns.

 

Joe L.

  • Author

Whoo, that's a relief.  Thank you for the help.  It still doesn't explain the first spontaneous parity check, but as long as it doesn't keep happening, I'll overlook it.

 

I'm familiar with the APC brand, but is there a particular model that you recommend?  I live in a city that generally has very clean and consistent power, so I'm not overly worried about it, but if I can find a UPS for $50-$100, I would consider it.

 

Thanks again for your mind-bogglingly quick response.

This tool on the APC website can help you "ballpark" just how large a UPS you require. http://www.apc.com/tools/ups_selector/index.cfm    I just purchased a UPS locally from Fry's, shipping and handling seemed to even out any price advantage online had versus local purchase.

 

See ya,

DQ

I have a APC Back-UPS ES 750 on my unRAID server.  It provides a nominal 450 watts of power.    It was on sale at a local store for $39. one day as I was walking by.  It communicates with the unRAID server via a USB cable connection.

 

According to its the apcaccess status report, my server is loading it at roughly 38% of its capacity.  It also says I have about 10 minutes of run-time in a power failure.  That is slightly misleading, as only one disk was spinning at the time I took the report shown in this post.  If I spin up all my drives I am at 57% capacity of the UPS and a predicted run-time of 6.7 minutes.

 

Between 6.7 and 10 minutes is sufficient to get me through any short term outage due to thunderstorms, etc.  Unfortunately, no consumer-style UPS would get me through extended outages.

(Several hundred thousand in my area lost power for 7 days as a result of major power company line failures that occurred as a result of a terrible ice-storm about 5 or 6 years ago, before I owned the unRAID server.)

 

You can see that my last power "blip" lasted for 1 second, on Jun 23rd at 12:35:15.

 

Joe L.

[pre]

(from /sbin/apcaccess status)

 

APC      : 001,039,1002

DATE    : Tue Jun 23 16:30:53 EDT 2009

HOSTNAME : Tower

RELEASE  : 3.14.3

VERSION  : 3.14.3 (20 January 2008) slackware

UPSNAME  : Tower

CABLE    : Custom Cable Smart

MODEL    : Back-UPS ES 750

UPSMODE  : Stand Alone

STARTTIME: Mon Jun 15 15:01:13 EDT 2009

STATUS  : ONLINE

LINEV    : 122.0 Volts

LOADPCT  :  38.0 Percent Load Capacity

BCHARGE  : 100.0 Percent

TIMELEFT :  10.8 Minutes

MBATTCHG : 5 Percent

MINTIMEL : 3 Minutes

MAXTIME  : 0 Seconds

SENSE    : Medium

LOTRANS  : 092.0 Volts

HITRANS  : 139.0 Volts

ALARMDEL : Always

BATTV    : 13.8 Volts

LASTXFER : Low line voltage

NUMXFERS : 3

XONBATT  : Tue Jun 23 12:35:15 EDT 2009

TONBATT  : 0 seconds

CUMONBATT: 4 seconds

XOFFBATT : Tue Jun 23 12:35:16 EDT 2009

SELFTEST : NO

STATFLAG : 0x07000008 Status Flag

MANDATE  : 2008-01-13

SERIALNO : 3B0802X63649 

BATTDATE : 2001-09-25

NOMINV  : 120 Volts

NOMBATTV :  12.0 Volts

NOMPOWER : 450 Watts

FIRMWARE : 841.I2 .D USB FW:I2

APCMODEL : Back-UPS ES 750

END APC  : Tue Jun 23 16:30:54 EDT 2009

[/pre]

 

 

 

 

  • Author

Is it difficult to set it up with unRAID (keep in mind that I have much less experience than you, and would have to be walked through all CLI proceedures)?

 

$39 is a good price.  Unfortunately, the closest Fry's is about 2 hours away, and we don't have any other big box computer retailers where I live (unless you could Best Buy, but they are always overpriced).  So I'm pretty limited to what I can buy online.

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