Tag Info

Hot answers tagged

11

Backups serve two functions. First and foremost, they're there to allow you to recover your data if it becomes unavailable. In this sense, snapshots are not backups. If you lose data on the filer (volume deletion, storage corruption, firmware error, etc.), all snapshots for that data are gone as well. Secondly, and far more commonly, backups are used to ...


8

Do you mean FC zoning? if so then it's basically something akin to a VLAN in that it allows you to hard-limit connections between devices. With only one big zone essentially all points can talk to all other points, this sounds good, especially when you have a proper switch which will help with bandwidth management (there used to be FC hubs bitd, showing my ...


7

Yes, the extensive command set of the SCSI is a big bonus of using it over SATA. from SAS' Wiki: SATA uses a command set that is based on the parallel ATA command set and then extended beyond that set to include features like native command queuing, hot-plugging, and TRIM. SAS uses the SCSI command set, which includes a wider range of features like error ...


6

They are a backup, yes. I've personally used them in place of daily incrementals before, but we still did weekly fulls to tape. They protect quite well from any non-netapp (systems accessing volumes) user or admin errors or problems. They do not protect from catastrophic hardware failures of the netapp itself. My understanding is that SnapMirror does copy ...


6

From http://technet.microsoft.com/en-us/library/ee619752(v=WS.10).aspx Configure the MPIO Failback policy setting If you use the Failover Only load-balancing policy setting, MPIO failback allows the configuration of a preferred I/O path to the storage, and allows automatic failback to be the preferred path if desired. Consider the following scenario: ...


6

If you have a single port on each switch that's logging in as a loop port, you need to address this. The first thing I'd do is try unplugging it and plugging it back in. If it still shows up as a loop port when it relogs back into the fabric, take a look at hard-coding the port to be an F port. I found instructions here. Be prepared that if there's some ...


4

SAN zoning is VERY important, and you should definitely do it. Conceptually, it's similar to a VLAN - but don' t be mislead. There are different reasons governing it's usage and purpose. A zone is a container, into which you place a set of SCSI initiators (the host bus adapters on your client) and a set of SCSI targets (the port(s) on your array). Each ...


2

The best way to think about zones is "software-defining your SCSI bus". In effect, you are coupling the SCSI bus of some servers and some storage ports together. As others have raised, it can help fault-tolerance, or access-control, or reduce the domain of state-change notifications. If your storage target triggers a bus-reset, do you want all your ...


2

How often you should scan depends on a lot of things. Age of the disks. The older they are, the more likely they are to contain evil. The original quality of the disks in question. Stuff sold as 'enterprise' is more likely to last error-free, and the 1+TB size disks of 2014 are a lot more reliable than their 2009 equivalents were when they shipped. How ...


2

As already mentioned above, setting up "zones" in SAN fabrics is done to promote fault isolation of devices from other devices on the same switch. Below are a couple of links to the Brocade documents which I find helpful on this subject of zoning. For a quick overview and tips, I'd look at pages 10 and 11 in the SAN Admin Best Practices guide: ...


1

You should inspect the output file to find out, what is in there. Knowing what is in the file helps figuring out, where it came from. For a starting point, you could try head -c10k /home/myuser/LvmName | hexdump -C and tail -c10k /home/myuser/LvmName | hexdump -C My guess is that it will either consist mostly of NUL characters or of some sort of text ...


1

I'd ask the SAN administrator. It's easier than guessing :) I mean, fdisk and dmesg will give you manufacturer info. But the answer to this depends on the make/model of the storage array. NetApp != HDS != Lefthand != EMC Can you give some more info about what you want to know? If you need SAN specs and don't readily have access to the administrator, ...


1

I know how it's done AIX, but a quick google on Linux brought me the sg3_utils package. You want to send a SCSI inquiry. Each storage will have their own way of replying- my VSP, for example, embeds the LDEV address, array serial number, and a bunch of other useful information into its reply. SCSI inquiries are a part of the SCSI protocol, meaning that it ...


1

Blocksizes has to be a multiple of the sector size, and all types of media I have ever worked with has had a block size of 512 bytes or more. If you want efficient storage of files much smaller than 512 bytes, you need to use a filesystem designed for that purpose. I know reiserfs is designed to perform tail-packing of files smaller than 12KB, which would ...


1

This depends entirely on the behaviour of your process when using its temporary storage. If your process holds a file open on /mnt, then you can't replace the device without causing the process to most probably fail in some undefined way, even if you manage to force-unmount the device. Processes generally don't expect devices on which they have open files ...


1

If process is using some directory for creating and deleting temporary files, you can probably try to stop it with kill -STOP $pid command and take a look into /proc/$pid/fd for opened file descriptors. If there is none opened, you can safely change mount location, copy it's files and continue in work with kill -CONT $pid. If there is still some opened or ...


1

Any program doing calculations that goes on for days should be designed to commit sufficient state to disk periodically. If a restart of the process means you lose an hour of processing time, that may be fine, but if you lose more than that, I'd call that program poorly designed. That said, there may be other scenarios, where you do want to keep a process ...


1

Speaking about hardware solutions I found no way to know exact hit ratio or something. I believe there are 2 reasons for that: the volume behind controller appears as a single drive (and so it should "just work"), and it is hard to count "hits" which will be not for files but rather for HDD sectors so there'll may be some hit rate even on empty HDD which may ...


1

I can't comment directly, as I'm not familiar with 3ware. However in general, I've run into quite a few storage arrays that 'steal' some disk space. There's a variety of reasons including: The controller runs a cut down OS, and needs space. (Config/management etc) The controller runs a write cache, and in the event of a power failure needs somewhere to ...


1

Span Ports or Mirror ports are great ways to mirror the actual traffic between the ports; it can lead to problems when exceeding the aggregate traffic of all ETLs (as Martin2341 mentions). Additionally (you mention Finisar Xgigs) the Span/Mirror ports don't see all the traffic. If you Xgig-Capture on those, you'll see that some B2B primitives are not ...


1

1) You need odd number of enclosures for enclosure awareness as with only two you're going to lose both data disk and witness disk for pool. Means cluster would be dead with 50% probability (depending on what actual enclosure would go South). So one is OK (no protection), three is OK, five is OK and four, six etc are NOT OK. 2) You need SAS JBODs ...


1

S.M.A.R.T. is not the final word in disk or storage monitoring!! It's a component, but modern RAID controllers use it along with other methods to determine drive and array health. I'm assuming this is a PERC controller in a Dell PowerEdge server. The normal Linux-friendly approach to health monitoring of Dell hardware is to install the Dell OMSA agents for ...


1

With mail server software, as with all software, you need to take a look under the hood and learn how the software works. For example Cyrus IMAPd uses Maildir format (at least by default), but in addition to that it has cyrus.{header,index,cache} files which it uses for improving performance. Thanks to those data files, it can return mail headers and other ...


1

While there might be an answer that gets you the info in the OS, odds are the controller firmware can tell you if you access it during boot. Another thing I noticed in your cut and paste is that your battery says "failed". I wonder if the stripes are reporting failure because the Write Cache battery is toast? Though it reporting and actual bad inode would ...


1

You should go read @Basil's excellent answer right now but here is my two cents: Snapshots are not application aware Just because you take a snapshot of the underlying storage volume does not mean the data on that volume is recoverable. MS SQL is a great example of this - you need to make sure your database is transaction-consistent before you snapshot the ...



Only top voted, non community-wiki answers of a minimum length are eligible