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• Keeping an Eye on Your Storage

  - by Fatherjack

  There are plenty of resources that advise you about looking for signs that your storage hardware is having problems. SQL Server Alerts for 823, 824 and 825 are covered here by Paul Randall of SQL Skills: http://www.sqlskills.com/blogs/paul/a-little-known-sign-of-impending-doom-error-825/ and here by me: https://www.simple-talk.com/blogs/2011/06/27/alerts-are-good-arent-they/. Now until very recently I wasn’t aware that there was a different way to track the 823 + 824 errors. It was by complete chance that I happened to be searching about in the msdb database when I found the suspect_pages table. Running a query against it I got zero rows. This, as it turns out is a good thing. Highlighting the table name and pressing F1 got me nowhere – Is it just me or does Books Online fail to load properly for no obvious reason sometimes? So I typed the table name into the search bar and got my local version of http://msdn.microsoft.com/en-us/library/ms174425.aspx. From that we get the following description: Contains one row per page that failed with a minor 823 error or an 824 error. Pages are listed in this table because they are suspected of being bad, but they might actually be fine. When a suspect page is repaired, its status is updated in the event_type column. So, in the table we would, on healthy hardware, expect to see zero rows but on disks that are having problems the event_type column would show us what is going on. Where there are suspect pages on the disk the rows would have an event_type value of 1, 2 or 3, where those suspect pages have been restored, repaired or deallocated by DBCC then the value would be 4, 5 or 7. Having this table means that we can set up SQL Monitor to check the status of our hardware as we can create a custom metric based on the query below: USE [msdb] go SELECT COUNT(*) FROM [dbo].[suspect_pages] AS sp All we need to do is set the metric to collect this value and set an alert to email when the value is not 1 and we are then able to let SQL Monitor take care of our storage. Note that the suspect_pages table does not have any updates concerning Error 825 which the links at the top of the page cover in more detail. I would suggest that you set SQL Monitor to alert on the suspect_pages table in addition to other taking other measures to look after your storage hardware and not have it as your only precaution. Microsoft actually pass ownership and administration of the suspect_pages table over to the database administrator (Manage the suspect_pages Table (SQL Server)) and in a surprising move (to me at least) advise DBAs to actively update and archive data in it. The table will only ever contain a maximum of 1000 rows and once full, new rows will not be added. Keeping an eye on this table is pretty important, although In my opinion, if you get to 1000 rows in this table and are not already waiting for new disks to be added to your server you are doing something wrong but if you have 1000 rows in there then you need to move data out quickly because you may be missing some important events on your server.

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• Persistent PuTTY sessions for multiple windows

  - by Tgr

  I'm working in various Linux environments through PuTTY connections which break from time to time. I'm looking for a solution to make the PuTTY windows persist (e.g. if I was editing a file, then after reconnecting I should be in the same editor with the same file open at the same place), with the following requirements: it shouldn't require any manual setup at the beginning of the session or after reconnection (I don't want to type in screen or anything like that) I have several windows open to the same machine with the same user, which tend to disconnect at the same time the number/role of windows is not constant (it's not like I have an mc window, a mysql window and a "script runner" window; sometimes I use one window for search or for SVN commands, other times I need several at the same time) sometimes I need to change the properties of the windows for a task (large window for grepping/editing, small windows because I need to see two of them at the same time, red background because I am modifying the live database in MySQL etc), so I need to get the same console back in the same window after a reconnect Is there a way to achieve this? I suppose I should use screen or something equivalent, but how does it know which window I am reconnecting from? Is there some way to pass a unique window identifier to the shell from PuTTY?

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• Network and Storage Devices Throughput Chart

  - by zroiy

  With all of the different storage and network devices that surround our day to day life, understanding these devices data transfer speeds can be somewhat confusing. Think about trying to identify your weakest link in the a chain that starts with an external USB hard drive (or a flash drive) that's connected to a 802.11g wifi router, can you quickly come up with an answer of where's the bottle neck in that chain , is it the router or the storage devices ? . Well, the following chart should give you an idea understanding different devices, protocols and interfaces maximum throughput speeds. Though these numbers can fluctuate (mostly for worse, but sometimes for the better) due to different kind of factors such as OS overhead (or caching and optimization) , multiple users or processes and so on , the chart can still serve to provide basic information on the theoretical throughput different devices and protocols can get to.. Enjoy.  Link to the full size chart   References:http://en.wikipedia.org/wiki/Sata#SATA_revision_1.0_.28SATA_1.5_Gbit.2Fs.29http://en.wikipedia.org/wiki/Usbhttp://en.wikipedia.org/wiki/Usb_3http://en.wikipedia.org/wiki/802.11http://mashable.com/2011/09/21/fastest-download-speeds-infographic/http://en.wikipedia.org/wiki/Thunderbolt_(interface)http://www.computerworld.com/s/article/9220434/Thunderbolt_vs._SuperSpeed_USB_3.0  Icons:http://openiconlibrary.sourceforge.net/gallery2/?./Icons/devices/drive-harddisk-3.png      

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• responsibility for storage

  - by Stefano Borini

  A colleague and I were brainstorming about where to put the responsibility of an object to store itself on the disk in our own file format. There are basically two choices: object.store(file) fileformatWriter.store(object) The first one gives the responsibility of serialization on the disk to the object itself. This is similar to the approach used by python pickle. The second groups the representation responsibility on a file format writer object. The data object is just a plain data container (eventually with additional methods not relevant for storage). We agreed on the second methodology, because it centralizes the writing logic from generic data. We also have cases of objects implementing complex logic that need to store info while the logic is in progress. For these cases, the fileformatwriter object can be passed and used as a delegate, calling storage operations on it. With the first pattern, the complex logic object would instead accept the raw file, and implement the writing logic itself. The first method, however, has the advantage that the object knows how to write and read itself from any file containing it, which may also be convenient. I would like to hear your opinion before starting a rather complex refactoring.

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• Azure Table Storage rejects an entity with a Property whose value is an Interface

  - by Andrew B Schultz

  I have a type called "Comment" that I'm saving to Azure Table Storage. Since a comment can be about any number of other types, I created an interface which all of these types implement, and then put a property of type ICommentable on the comment. So Comment has a property called About of type ICommentable. When I try to save a Comment to Azure Table Storage, if the Comment.About property has a value, I get the worthless invalid input error. However, if there is no value for Comment.About, I have no problem. Why would this be? Comment.About is not the only property that is a reference type. For example, Comment.From is a reference type, but the Comment.About is the only property of a type that is an interface. Fails: var comment = new Comment(); comment.CommentText = "It fails!"; comment.PartitionKey = "TEST"; comment.RowKey = "TEST123"; comment.About = sow1; comment.From = person1; Works: var comment = new Comment(); comment.CommentText = "It works!"; comment.PartitionKey = "TEST"; comment.RowKey = "TEST123"; //comment.About = sow1; comment.From = person1; Thanks!

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• Game-Changing New Technology for Datacenter Storage

  - by Lajos Sárecz

  Ma este 18 órától tart az Oracle egy publikus webcast-ot, mely keretében egy új storage technológia kerül bejelentésre. Aki az adattárolási költségeit szeretné csökkenteni és egyúttal hatékonyabbá tenni (ki ne szeretné ezt?), annak érdemes beregisztrálnia. A hírek szerint ugyanis ez az új technológia jelentos teljesítmény növekedést eredményez a tárolási költségek csökkentése mellett, ráadásul nagy kapacitással és archiválás valamint adatvédelem szempontjából újszeru képességekkel érkezik.

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• Android XML Preference issue. Can't make it persistent

  - by Budius

  I have a very simple activity just to show the preference fragment: public class PreferencesActivity extends Activity { Fragment frag = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); FragmentTransaction ft = getFragmentManager().beginTransaction(); if (frag == null) { // If not, instantiate and add it to the activity frag = new PrefsFragment(); ft.add(android.R.id.content, frag, frag.getClass().getName()); } else { // If it exists, simply attach it in order to show it ft.attach(frag); } ft.commit(); } private static class PrefsFragment extends PreferenceFragment { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.preferences); } } } and preferences.xml with persistent to true: <?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" android:enabled="true" android:persistent="true" android:title="@string/settings" > <EditTextPreference android:dialogTitle="@string/dialog_ip" android:negativeButtonText="@android:string/cancel" android:persistent="true" android:positiveButtonText="@android:string/ok" android:title="@string/ip" /> </PreferenceScreen> if I open the EditTextPreference, write something, close the dialog and open it again. The value is still there. But that's it... if I click the Back button, and enter the again on the preferences screen, I already lost what was written. If you exit the application also doesn't save. Am I missing something here? Running on: Android 4.0.3 Asus TF300

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• iOS persistant storage with update function

  - by jernej

  im developing a game which has different levels and i need to store all levels and its elements (position, image, sounds,..) into a file/database. The levels will be updated so i need a function that checks online for a update and downloads a database dump and additional files. I was planing to store all the persistent data into a SQLLite database, but not quite sure how to do the update part - to pack the database dump and the files together (in a .zip or with a xml). Can this be done any other way (as secure as possible)? thanks!

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• storage terms clarification required

  - by kumar

  Hi, Having written some network drivers , I m bit new to storage world. I m hearing new terms like RAID,SATA,ATA,AHCI, etc., in this world. Please throw some light and relation between them Thx!

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• Slow NFS and GFS2 performance

  - by Tiago

  Recently I've designed and configured a 4 node cluster for a webapp that does lots of file handling. The cluster have been broken down into 2 main roles, webserver and storage. Each role is replicated to a second server using drbd in active/passive mode. The webserver does a NFS mount of the data directory of the storage server and the latter also has a webserver running to serve files to browser clients. In the storage servers I've created a GFS2 FS to hold the data which is wired to drbd. I've chose GFS2 mainly because the announced performance and also because the volume size which has to be pretty high. Since we entered production I've been facing two problems that I think are deeply connected. First of all, the NFS mount on the webservers keeps hanging for a minute or so and then resumes normal operations. By analyzing the logs I've found out that NFS stops answering for a while and outputs the following log lines: Oct 15 18:15:42 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:44 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:46 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:47 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:48 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:48 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:51 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:52 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:52 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:55 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:55 <server hostname> kernel: nfs: server active.storage.vlan not responding, still trying Oct 15 18:15:58 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK Oct 15 18:15:59 <server hostname> kernel: nfs: server active.storage.vlan OK In this case, the hang lasted for 16 seconds but sometimes it takes 1 or 2 minutes to resume normal operations. My first guess was this was happening due to heavy load of the NFS mount and that by increasing RPCNFSDCOUNT to a higher value, this would become stable. I've increased it several times and apparently, after a while, the logs started appearing less times. The value is now on 32. After further investigating the issue, I've came across a different hang, despite the NFS messages still appear in the logs. Sometimes, the GFS2 FS simply hangs which causes both the NFS and the storage webserver to serve files. Both stay hang for a while and then they resume normal operations. This hangs leaves no trace on client side (also leaves no NFS ... not responding messages) and, on the storage side, the log system appears to be empty, even though the rsyslogd is running. The nodes connect themselves through a 10Gbps non-dedicated connection but I don't think this is an issue because the GFS2 hang is confirmed but connecting directly to the active storage server. I've been trying to solve this for a while now and I've tried different NFS configuration options, before I've found out the GFS2 FS is also hanging. The NFS mount is exported as such: /srv/data/ <ip_address>(rw,async,no_root_squash,no_all_squash,fsid=25) And the NFS client mounts with: mount -o "async,hard,intr,wsize=8192,rsize=8192" active.storage.vlan:/srv/data /srv/data After some tests, these were the configurations that yielded more performance to the cluster. I am desperate to find a solution for this as the cluster is already in production mode and I need to fix this so that this hangs won't happen in the future and I don't really know for sure what and how I should be benchmarking. What I can tell is that this is happening due to heavy loads as I have tested the cluster earlier and this problems weren't happening at all. Please tell me if you need me to provide configuration details of the cluster, and which do you want me to post. As last resort I can migrate the files to a different FS but I need some solid pointers on whether this will solve this problems as the volume size is extremely large at this point. The servers are being hosted by a third-party enterprise and I don't have physical access to them. Best regards. EDIT 1: The servers are physical servers and their specs are: Webservers: Intel Bi Xeon E5606 2x4 2.13GHz 24GB DDR3 Intel SSD 320 2 x 120GB Raid 1 Storage: Intel i5 3550 3.3GHz 16GB DDR3 12 x 2TB SATA Initially there was a VRack setup between the servers but we've upgraded one of the storage servers to have more RAM and it wasn't inside the VRack. They connect through a shared 10Gbps connection between them. Please note that it is the same connection that is used for public access. They use a single IP (using IP Failover) to connect between them and to allow for a graceful failover. NFS is therefore over a public connection and not under any private network (it was before the upgrade, were the problem still existed). The firewall was configured and tested thoroughly but I disabled it for a while to see if the problem still occurred, and it did. From my knowledge the hosting provider isn't blocking or limiting the connection between either the servers and the public domain (at least under a given bandwidth consumption threshold that hasn't been reached yet). Hope this helps figuring out the problem. EDIT 2: Relevant software versions: CentOS 2.6.32-279.9.1.el6.x86_64 nfs-utils-1.2.3-26.el6.x86_64 nfs-utils-lib-1.1.5-4.el6.x86_64 gfs2-utils-3.0.12.1-32.el6_3.1.x86_64 kmod-drbd84-8.4.2-1.el6_3.elrepo.x86_64 drbd84-utils-8.4.2-1.el6.elrepo.x86_64 DRBD configuration on storage servers: #/etc/drbd.d/storage.res resource storage { protocol C; on <server1 fqdn> { device /dev/drbd0; disk /dev/vg_storage/LV_replicated; address <server1 ip>:7788; meta-disk internal; } on <server2 fqdn> { device /dev/drbd0; disk /dev/vg_storage/LV_replicated; address <server2 ip>:7788; meta-disk internal; } } NFS Configuration in storage servers: #/etc/sysconfig/nfs RPCNFSDCOUNT=32 STATD_PORT=10002 STATD_OUTGOING_PORT=10003 MOUNTD_PORT=10004 RQUOTAD_PORT=10005 LOCKD_UDPPORT=30001 LOCKD_TCPPORT=30001 (can there be any conflict in using the same port for both LOCKD_UDPPORT and LOCKD_TCPPORT?) GFS2 configuration: # gfs2_tool gettune <mountpoint> incore_log_blocks = 1024 log_flush_secs = 60 quota_warn_period = 10 quota_quantum = 60 max_readahead = 262144 complain_secs = 10 statfs_slow = 0 quota_simul_sync = 64 statfs_quantum = 30 quota_scale = 1.0000 (1, 1) new_files_jdata = 0 Storage network environment: eth0 Link encap:Ethernet HWaddr <mac address> inet addr:<ip address> Bcast:<bcast address> Mask:<ip mask> inet6 addr: <ip address> Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:957025127 errors:0 dropped:0 overruns:0 frame:0 TX packets:1473338731 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:2630984979622 (2.3 TiB) TX bytes:1648430431523 (1.4 TiB) eth0:0 Link encap:Ethernet HWaddr <mac address> inet addr:<ip failover address> Bcast:<bcast address> Mask:<ip mask> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 The IP addresses are statically assigned with the given network configurations: DEVICE="eth0" BOOTPROTO="static" HWADDR=<mac address> ONBOOT="yes" TYPE="Ethernet" IPADDR=<ip address> NETMASK=<net mask> and DEVICE="eth0:0" BOOTPROTO="static" HWADDR=<mac address> IPADDR=<ip failover> NETMASK=<net mask> ONBOOT="yes" BROADCAST=<bcast address> Hosts file to allow for a graceful NFS failover in conjunction with NFS option fsid=25 set on both storage servers: #/etc/hosts <storage ip failover address> active.storage.vlan <webserver ip failover address> active.service.vlan As you can see, packet errors are down to 0. I've also ran ping for a long time without any packet loss. MTU size is the normal 1500. As there is no VLan by now, this is the MTU used to communicate between servers. The webservers' network environment is similar. One thing I forgot to mention is that the storage servers handle ~200GB of new files each day through the NFS connection, which is a key point for me to think this is some kind of heavy load problem with either NFS or GFS2. If you need further configuration details please tell me. EDIT 3: Earlier today we had a major filesystem crash on the storage server. I couldn't get the details of the crash right away because the server stop responding. After the reboot, I noticed the filesystem was extremely slow, and I was not being able to serve a single file through either NFS or httpd, perhaps due to cache warming or so. Nevertheless, I've been monitoring the server closely and the following error came up in dmesg. The source of the problem is clearly GFS, which is waiting for a lock and ends up starving after a while. INFO: task nfsd:3029 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. nfsd D 0000000000000000 0 3029 2 0x00000080 ffff8803814f79e0 0000000000000046 0000000000000000 ffffffff8109213f ffff880434c5e148 ffff880624508d88 ffff8803814f7960 ffffffffa037253f ffff8803815c1098 ffff8803814f7fd8 000000000000fb88 ffff8803815c1098 Call Trace: [<ffffffff8109213f>] ? wake_up_bit+0x2f/0x40 [<ffffffffa037253f>] ? gfs2_holder_wake+0x1f/0x30 [gfs2] [<ffffffff814ff42e>] __mutex_lock_slowpath+0x13e/0x180 [<ffffffff814ff2cb>] mutex_lock+0x2b/0x50 [<ffffffffa0379f21>] gfs2_log_reserve+0x51/0x190 [gfs2] [<ffffffffa0390da2>] gfs2_trans_begin+0x112/0x1d0 [gfs2] [<ffffffffa0369b05>] ? gfs2_dir_check+0x35/0xe0 [gfs2] [<ffffffffa0377943>] gfs2_createi+0x1a3/0xaa0 [gfs2] [<ffffffff8121aab1>] ? avc_has_perm+0x71/0x90 [<ffffffffa0383d1e>] gfs2_create+0x7e/0x1a0 [gfs2] [<ffffffffa037783f>] ? gfs2_createi+0x9f/0xaa0 [gfs2] [<ffffffff81188cf4>] vfs_create+0xb4/0xe0 [<ffffffffa04217d6>] nfsd_create_v3+0x366/0x4c0 [nfsd] [<ffffffffa0429703>] nfsd3_proc_create+0x123/0x1b0 [nfsd] [<ffffffffa041a43e>] nfsd_dispatch+0xfe/0x240 [nfsd] [<ffffffffa025a5d4>] svc_process_common+0x344/0x640 [sunrpc] [<ffffffff810602a0>] ? default_wake_function+0x0/0x20 [<ffffffffa025ac10>] svc_process+0x110/0x160 [sunrpc] [<ffffffffa041ab62>] nfsd+0xc2/0x160 [nfsd] [<ffffffffa041aaa0>] ? nfsd+0x0/0x160 [nfsd] [<ffffffff81091de6>] kthread+0x96/0xa0 [<ffffffff8100c14a>] child_rip+0xa/0x20 [<ffffffff81091d50>] ? kthread+0x0/0xa0 [<ffffffff8100c140>] ? child_rip+0x0/0x20

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• IBM storage ds3400 Cant connect to management using fiber

  - by Eli B

  i have a problem with a DS3400 IBM storage system we bought a few years back. when i try to manage the storage using its IBM storage management i cant find it using automatic detection even though its connected directly using the fiber and i can see the Logical drives connected and working properly. when i tried to connect the two management Ethernet wires and manage the storage directly by entering the IP address manually i am able to connect however after i make several changes to the controller configuration one of the controllers stops responding and i am not able to ping it directly (since you cant make any changes without being connected to both controllers this is a problem) whats more bizarre is that when i change the IP of the controller that doesn't respond it starts working .. i have found some articles over the web explaining stuff about LUN31 being missing and causing similar problems however all my attempts to manually configure it failed . *link to an example http://www-947.ibm.com/support/entry/portal/docdisplay?lndocid=MIGR-5075711 in short im trying to get my storage to appear in the storage manager when directly connected using only the fiber cable directly attached. thanks in advance

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• Ideas for reducing storage needs and/or costs (lots of images)

  - by James P.

  Hi, I'm the webmaster for a small social network and have noticed that images uploaded by users are taking a big portion of the capacity available. These are mostly JPEGs. What solutions could I apply to reduce storage needs? Is there a way to reduce the size of images without affecting quality too much? Is there a service out there that could be used to store static files at a cheaper price (< 1GB/0.04 eurocents)? Edit: Updated the question.

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• Windows Phone 8 detected as mass storage

  - by legends2k

  From version 8 onwards Windows Phone supports MTP (media transfer protocol) to transfer audio and I thought I could use Rhythmbox to upload music onto my device. Thing is Rhythmbox doesn't display the device under Devices pane (there's no Device pane for that matter). I searched other questions here and tried out installing mtp-tools, mtpfs and also tried gMTP, which doesn't seem to detect the device as a portable player. I see that the device's icon looks like a Camera in dash bar and when I see the address location, it shows gphoto2://[usb:002,013]/, which makes me doubt that it's detected as a camera or as a mass storage device. /.gvfs/gphoto2 mount on usb%3A002,003 is where the actual mount is. What do I do to fix this? I tried creating .is_audio_player too.

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• What are the best Small Business Servers/Storage

  - by nasty

  I am a web designer/developer. Work mostly with large files 50mb+. I currently have a MyBook Live which is connected wirelessly to my MacBook Pro and Dell desktop PC running windows. Since its connected wirelessly(it doesnt have ethernet port) the files are loading slow and its hard to work staright away from my server. Now im looking for better storage/server solutions and looking at dell.com.au/servers. Im not sure which one to choose. Can you guys give me some suggestions whether I should buy the AUD599 or should I upgrade. Is there any stack guys haveing the same issue as me? t

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• Tornado Web & Persistent Connections

  - by Engrost

  How can I write Http server in TornadoWeb that will support persistent Connections. I mean will be able to receive many requests and answer to them without closing connection. How does it actually work in async? I just want to know how to write handler to handle persistent connection. How actually would it work? I have handler like that: class MainHandler(RequestHandler): count = 0 @asynchronous def post(self): #get header content type content_type = self.request.headers.get('Content-Type') if not content_type in ACCEPTED_CONTENT: raise HTTPError(403, 'Incorrect content type') text = self.request.body self.count += 1 command = CommandObject(text, self.count, callback = self.async_callback(self.on_response)) command.execute() def on_response(self, response): if response.error: raise HTTPError(500) body = response.body self.write(body) self.flush() execute calls callback when finishes. is my asumption right that with things that way post will be called many times and for one connection count will increase with each httprequest from client? but for each connection I will have separate count value?

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• "One of the request inputs not valid" error when attempting to update Azure Table Storage

  - by sako73

  I am attempting to update an entry in Azure Table Storage. The function is: public void SaveBug(DaBug bug) { bug.PartitionKey = "bugs"; bug.Timestamp = DateTime.UtcNow; if (bug.RowKey == null || bug.RowKey == string.Empty) { bug.RowKey = Guid.NewGuid().ToString(); _context.AddObject(c_TableName, bug); } else { _context.AttachTo(c_TableName, bug); _context.UpdateObject(bug); } _context.SaveChanges(); } If it is a new entry (the "bug.RowKey == null" path), then it works fine. If it is an update to an existing entity, then the "AttachTo", and the "UpdateObject" calls work, but when it gets to "SaveChanges", it throws the "One of the request inputs not valid" exception. The class that is being stored is: [DataContract] [DataServiceKey("RowKey")] public class DaBug { [DataMember] public bool IsOpen { get; set; } [DataMember] public string Title { get; set; } [DataMember] public string Description { get; set; } [DataMember] public string SubmittedBy { get; set; } [DataMember] public DateTime SubmittedDate { get; set; } [DataMember] public string RowKey { get; set; } public DateTime Timestamp { get; set; } public string PartitionKey { get; set; } } Does anyone know what the problem is? Thanks for any help.

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• Oracle's Sun ZFS Storage Appliances and Oracle VM

  - by uwes

  Oracle's Sun ZFS Storage Appliance Is the Optimal Platform for Deploying Consolidated Applications in an Oracle Virtual Machine (OVM) Environment Unsurpassed Integration - Oracle VM and Storage Engineering teams provide seamless integration points and an Oracle VM Connect Plug-In for Sun ZFS Storage Appliance in FC, NFS, and iSCSI Environments.  And Sun ZFS Storage is engineered and tested to work with Oracle VM agility features including Live (VM) Migration and oracle RAC Live Migration. More information could befound under the following links: ZFS Storage Appliance Server Virtualization Oracle.com page ZFS Storage Appliance Oracle.com page ZFS Storage Appliance Oracle Technical Network.com page Software download support.oracle.com page

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• DAS vs SAN storage for serving 2 to 4 nodes

  - by Luke404

  We currently have 4 Linux nodes with local storage, arranged in two active/passive pairs with storage mirrored using DRBD, running virtual machines (actually using Xen Hypervisor) for typical hosting workloads (mail, web, a couple VPS, etc.). We're approaching the (presumed) maximum IOPS of those servers, and we're planning to migrate to an external storage solution with two active nodes, with capacity for up to four active nodes. Since we're an all-Dell shop I've done some research and found the MD3200 / MD3200i products should be the ones we're looking for. We are pretty sure we won't be attaching more than 4 hosts on a single storage and I'm wondering if there is any clear advantage for one or the other. In theory I should be able to attach 4 SAS hosts to a single MD3200 (single links on a single controller MD3200, or dual redundant SAS links from each host to a dual-controller MD3200), or 4 iSCSI hosts to a single MD3200i (directly on its 4 GigE ports without any switch, again with dual links for the dual controller option). Both setups should let us implement live VM migration since all hosts can access all the LUNs at the same time, and also some shared filesystem like GFS2 or OCFS2. Also, both setups should allow full redundancy of the whole system (assuming dual controllers in the storage). One difference I can see is that the DAS solution is actually limited to 4 hosts while the iSCSI one should be able to grow to more hosts (adding two GigE switches to the mix). One point for the iSCSI solution is that it would allow us to start out with our current nodes and upgrade them at a later time (we can't add other SAS controllers, but they already have 4 GigE ports each). With the right (iSCSI|SAS) controllers I should be able to connect diskless nodes and boot them off the external storage which I think is a good thing (get rid of any local storage). On the other hand, I would have thought the SAS one to be cheaper but it seems like an MD3200 actually costs a little less than an MD3200i (?) (please note: I've used Dell gear in my examples since that's what we're looking for but I assume the same goes with other vendors) I would like to know if my assumptions above are correct, and if I'm missing any important difference between the two setups.

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• Moving data files failing

  - by Miles Hayler

  Trying to migrate data from C: to D: via the SBS console is failing. The wizard starts running but drops out in the first few seconds. I'll post the full logs, but the important lines appear to be as follows: An exception of type 'Type: System.IO.FileNotFoundException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' has occurred. Message: The system cannot find the file specified. (Exception from HRESULT: 0x80070002) Stack: at TaskScheduler.TaskSchedulerClass.GetFolder(String Path) at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) BaseException: Microsoft.WindowsServerSolutions.Storage.Common.StorageException: GetServerBackupTaskStatus: fail to find the task --- ErrorCode:0 I've been googling for days with no luck. I have found that mscorlib is a component of .net, and I've discovered multiple instances of the file in %windir%, %windir%\winsxs, %windir%\Microsoft.net Anyone come across and fixed this one before? --------------------------------------------------------- [1516] 110315.190856.1105: Storage: Initializing...C:\Program Files\Windows Small Business Server\Bin\MoveData.exe [1516] 110315.190856.2875: Storage: Data Store to be moved: Exchange [1516] 110315.190856.5305: TaskScheduler: Exception System.IO.FileNotFoundException: [1516] 110315.190856.5605: Exception: --------------------------------------- An exception of type 'Type: System.IO.FileNotFoundException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' has occurred. Timestamp: 03/15/2011 19:08:56 Message: The system cannot find the file specified. (Exception from HRESULT: 0x80070002) Stack: at TaskScheduler.TaskSchedulerClass.GetFolder(String Path) at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) [1516] 110315.190856.5625: Storage: Exception Microsoft.WindowsServerSolutions.Common.WindowsTaskSchedulerException: [1516] 110315.190856.5635: Exception: --------------------------------------- [b]An exception of type 'Type: Microsoft.WindowsServerSolutions.Common.WindowsTaskSchedulerException, Common, Version=6.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' has occurred.[/b] Timestamp: 03/15/2011 19:08:56 Message: Failed to find the task path Stack: at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) at Microsoft.WindowsServerSolutions.Storage.Common.ServerBackupUtility.GetServerBackupTaskStatus() --------------------------------------- An exception of type 'Type: System.IO.FileNotFoundException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' has occurred. Timestamp: 03/15/2011 19:08:56 Message: The system cannot find the file specified. (Exception from HRESULT: 0x80070002) Stack: at TaskScheduler.TaskSchedulerClass.GetFolder(String Path) at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) [1516] 110315.190856.5665: Storage: Error Retrieving Server Backup Task Status: ErrorCode:0 BaseException: Microsoft.WindowsServerSolutions.Storage.Common.StorageException: GetServerBackupTaskStatus: fail to find the task ---> ErrorCode:0 BaseException: Microsoft.WindowsServerSolutions.Common.WindowsTaskSchedulerException: Failed to find the task path ---> System.IO.FileNotFoundException: The system cannot find the file specified. (Exception from HRESULT: 0x80070002) at TaskScheduler.TaskSchedulerClass.GetFolder(String Path) at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) --- End of inner exception stack trace --- at Microsoft.WindowsServerSolutions.Common.WindowsTaskScheduler..ctor(String taskPath, String taskName) at Microsoft.WindowsServerSolutions.Storage.Common.ServerBackupUtility.GetServerBackupTaskStatus() --- End of inner exception stack trace --- at Microsoft.WindowsServerSolutions.Storage.Common.ServerBackupUtility.GetServerBackupTaskStatus() at Microsoft.WindowsServerSolutions.Storage.MoveData.Helper.get_ServerBackupTaskState() [1516] 110315.190857.6216: Storage: Backup Task State: Unknown [1516] 110315.190857.9347: Storage: Launching the Move Data Wizard! [1516] 110315.190857.9397: Wizard: Admin:QueryNextPage(null) = Storage.MoveDataWizard.GettingStartedPage [1516] 110315.190857.9417: Wizard: TOC Storage.MoveDataWizard.GettingStartedPage is on ExpectedPath [1516] 110315.190857.9577: Wizard: Storage.MoveDataWizard.GettingStartedPage entered [1516] 110315.190857.9657: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.GettingStartedPage) = Storage.MoveDataWizard.DiagnoseDataStorePage [1516] 110315.190857.9657: Wizard: TOC Storage.MoveDataWizard.DiagnoseDataStorePage is on ExpectedPath [1516] 110315.190857.9657: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.DiagnoseDataStorePage) = Storage.MoveDataWizard.NewDataStoreLocationPage [1516] 110315.190857.9657: Wizard: TOC Storage.MoveDataWizard.NewDataStoreLocationPage is on ExpectedPath [1516] 110315.190857.9657: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.NewDataStoreLocationPage) = null [1516] 110315.190857.9697: Wizard: ---------------------------------- [1516] 110315.190857.9697: Wizard: The pages visted: [1516] 110315.190857.9697: Wizard: Current Page := [TOC Storage.MoveDataWizard.GettingStartedPage] [1516] 110315.190857.9697: Wizard: [TOC] : TOC Storage.MoveDataWizard.DiagnoseDataStorePage [1516] 110315.190857.9697: Wizard: [TOC] : TOC Storage.MoveDataWizard.NewDataStoreLocationPage [1516] 110315.190857.9697: Wizard: Step 1 of 3 [1516] 110315.190907.0406: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.GettingStartedPage) = Storage.MoveDataWizard.DiagnoseDataStorePage [1516] 110315.190907.0416: Wizard: Storage.MoveDataWizard.GettingStartedPage exited with the button: Next [1516] 110315.190907.0416: WizardChainEngine Next Clicked: Going to page {0}.: Storage.MoveDataWizard.DiagnoseDataStorePage [1516] 110315.190907.0496: Wizard: Storage.MoveDataWizard.DiagnoseDataStorePage entered [1516] 110315.190907.0606: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.DiagnoseDataStorePage) = Storage.MoveDataWizard.NewDataStoreLocationPage [1516] 110315.190907.0606: Wizard: Admin:QueryNextPage(Storage.MoveDataWizard.NewDataStoreLocationPage) = null [1516] 110315.190907.0606: Wizard: ---------------------------------- [1516] 110315.190907.0606: Wizard: The pages visted: [1516] 110315.190907.0606: Wizard: [TOC] visited: TOC Storage.MoveDataWizard.GettingStartedPage [1516] 110315.190907.0606: Wizard: Current Page := [TOC Storage.MoveDataWizard.DiagnoseDataStorePage] [1516] 110315.190907.0616: Wizard: [TOC] : TOC Storage.MoveDataWizard.NewDataStoreLocationPage [1516] 110315.190907.0616: Wizard: Step 2 of 3 [19772] 110315.190907.0656: Storage: Starting System Diagnosis [19772] 110315.190907.0656: Storage: Getting Data Store Information [19772] 110315.190907.1086: Storage: Create the list of storage and DB directory path [19772] 110315.190907.1246: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingTasks..ctor [19772] 110315.190907.1546: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingTasks.Initialize [19772] 110315.190907.1596: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.Initialize [19772] 110315.190907.1606: Messaging: Exchange install path: C:\Program Files\Microsoft\Exchange Server\bin [19772] 110315.190908.4157: Messaging: E12 Monad runspace created ID: Microsoft.PowerShell [19772] 110315.190908.4237: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190908.4287: Messaging: Executed management shell command: get-exchangeserver [19772] 110315.190910.2369: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190910.2369: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.Initialize [19772] 110315.190910.5699: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingTasks.GatherAdminInfo [19772] 110315.190910.5699: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190910.5719: Messaging: Executed management shell command: get-user -Identity "dmagroup.local\Administrator" [19772] 110315.190911.0870: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.0880: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.0880: Messaging: Executed management shell command: get-mailbox -Identity "d2ae2bf0-48a7-4ce9-9e72-bb3c765454ac" [19772] 110315.190911.1300: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.1310: Messaging: User Administrator is mail enabled and can use MessagingManagement to send mail. [19772] 110315.190911.1310: Messaging: Email address used for user: [email protected] [19772] 110315.190911.1440: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.1440: Messaging: Executed management shell command: get-group -Identity "Domain Admins" [19772] 110315.190911.1630: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.1640: Messaging: User Administrator is a member of Domain Admins and can use MessagingManagement to manage Exchange. [19772] 110315.190911.1640: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingTasks.GatherAdminInfo [19772] 110315.190911.1640: Messaging: MessagingManagement enabled for Exchange management: True [19772] 110315.190911.1640: Messaging: MessagingManagement enabled for mail submission: True [19772] 110315.190911.1640: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingTasks.Initialize [19772] 110315.190911.1640: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Tasks.TaskMoveExchangeData.CreateDataStoreDriveList [19772] 110315.190911.1670: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.Initialize [19772] 110315.190911.1670: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.1670: Messaging: Executed management shell command: get-storagegroup -Server "SERVER01" [19772] 110315.190911.2990: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.3070: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.Initialize [19772] 110315.190911.3070: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.3070: Messaging: Executed management shell command: get-mailboxdatabase -Server "SERVER01" [19772] 110315.190911.4440: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.4520: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.Initialize [19772] 110315.190911.4520: Messaging: Begin Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.4520: Messaging: Executed management shell command: get-publicfolderdatabase -Server "SERVER01" [19772] 110315.190911.5240: Messaging: End Microsoft.WindowsServerSolutions.Messaging.Management.MessagingRunspace.StaticExecute [19772] 110315.190911.5510: Storage: Data Store Drive/s Details:Name=C:\,Size=12675712420 [19772] 110315.190911.5510: Storage: Data Store Size Details: Current Total Size=12675712420 Required Size=12675712420 [19772] 110315.190911.5510: Storage: MoveData Task can move the Data Store=True [19772] 110315.190911.8401: Storage: An error was encountered when performing system diagnosis : ErrorCode:0 BaseException: Microsoft.WindowsServerSolutions.Storage.Common.StorageException: WMI error occurred while accessing drive ---> System.Management.ManagementException: Not found at System.Management.ManagementException.ThrowWithExtendedInfo(ManagementStatus errorCode) at System.Management.ManagementObjectCollection.ManagementObjectEnumerator.MoveNext() at Microsoft.WindowsServerSolutions.Storage.Common.DriveUtil.IsDriveRemovable(String drive) --- End of inner exception stack trace --- at Microsoft.WindowsServerSolutions.Storage.Common.DriveUtil.IsDriveRemovable(String drive) at Microsoft.WindowsServerSolutions.Storage.Common.DataStoreInfo.LoadAvailableDrives() at Microsoft.WindowsServerSolutions.Storage.Common.MoveDataUtil.CanMoveData(DataStoreInfo storeInfo, MoveDataError& error) at Microsoft.WindowsServerSolutions.Storage.MoveData.DiagnoseDataStorePagePresenter.DiagnoseDataStore(Object sender, DoWorkEventArgs args) [1516] 110315.190912.0331: Storage: An error occured during the execution: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> ErrorCode:0 BaseException: Microsoft.WindowsServerSolutions.Storage.Common.StorageException: Diagnosing the Data Store failed (see the inner exception) ---> ErrorCode:0 BaseException: Microsoft.WindowsServerSolutions.Storage.Common.StorageException: WMI error occurred while accessing drive ---> System.Management.ManagementException: Not found at System.Management.ManagementException.ThrowWithExtendedInfo(ManagementStatus errorCode) at System.Management.ManagementObjectCollection.ManagementObjectEnumerator.MoveNext() at Microsoft.WindowsServerSolutions.Storage.Common.DriveUtil.IsDriveRemovable(String drive) --- End of inner exception stack trace --- at Microsoft.WindowsServerSolutions.Storage.Common.DriveUtil.IsDriveRemovable(String drive) at Microsoft.WindowsServerSolutions.Storage.Common.DataStoreInfo.LoadAvailableDrives() at Microsoft.WindowsServerSolutions.Storage.Common.MoveDataUtil.CanMoveData(DataStoreInfo storeInfo, MoveDataError& error) at Microsoft.WindowsServerSolutions.Storage.MoveData.DiagnoseDataStorePagePresenter.DiagnoseDataStore(Object sender, DoWorkEventArgs args) at System.ComponentModel.BackgroundWorker.WorkerThreadStart(Object argument) --- End of inner exception stack trace --- at Microsoft.WindowsServerSolutions.Storage.MoveData.DiagnoseDataStorePagePresenter.backgroundWorker_RunWorkerCompleted(Object sender, RunWorkerCompletedEventArgs e) --- End of inner exception stack trace --- at System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner) at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks) at System.Delegate.DynamicInvokeImpl(Object[] args) at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme) at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme) at System.Windows.Forms.Control.InvokeMarshaledCallbacks() at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData) at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) at Microsoft.WindowsServerSolutions.Common.Wizards.Framework.WizardFrameView.Create() at Microsoft.WindowsServerSolutions.Common.Wizards.Framework.WizardChainEngine.Launch() at Microsoft.WindowsServerSolutions.Storage.MoveData.MainClass.LaunchMoveDataWizard() at Microsoft.WindowsServerSolutions.Storage.MoveData.MainClass.Main(String[] args)

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• Why Buy Hardrives with storage server from a vendor?

  - by Mark

  Hi all, Im just browsing around at storage server's like the Dell MD100/ MD3000 and the Sun J4200 and although the storage server seems reasonable (approx $3000-$4000 AUD) the hard-drives that you buy to go along with them seems exorbitantly expensive. And I'm not sure why. Surely at most they are using good quality RAID level 7200rpm SATA hdd, but even then they are still charging almost 4 times the price. What is the advantage to buying these from them. I can see if one fails then the vendor replacing it is convenient. But at that price you could buy double the amount of hdd and just claim on warranty directly with the manufacturer. It would be much cheaper and you wouldn't be relying on someone else to fix your problems. Is this the case of "you don't get fired if you buy IBM?" mentality or is there some reason I'm not grasping here? Cheers Mark

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• Nexenta storage metro cluster - what are components involved?

  - by Jiri Xichtkniha

  I'm quite imporesses that Nexenta can build storage metro cluster (site to site storage mirroring). As Nexenta is built on Illumos (successor of OpenSolaris) I was thinking what kind of components are involved in their storage metro cluster. Could anybody enlight me what components are doing this site-site mirroring and if these components are open source so one can build similar storage metro cluster on his own? ZFS is local filesystem so what takes care of clustering?

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• Product Launch: Oracle Optimized Storage: Solutions for Simplifying IT

  - by swalker

  On July 18, 2012 at 10am PT 17pm UK Time, Oracle is hosting an online storage launch event featuring Mark Hurd, John Fowler, and several other Oracle executives.  This event will consist of 3 different webcasts, all detailing our latest messaging, momentum, and product innovations. Highlights include: Even in the most advanced data centers, outdated and inefficient storage management techniques are stifling business innovation. But now you can deploy Oracle’s optimized storage, the industry’s most advanced, easy-to-use, and cost-effective enterprise storage solutions. Learn about the benefits of Oracle’s latest storage innovations, including: How you can take on the biggest enterprise storage infrastructure challenges—including reducing costs and increasing data management efficiency A deep-dive discussion into Oracle’s storage innovations, featuring the leaders of Oracle’s storage development organizations A first look at Oracle’s newest scalable storage solution for midsize businesses Join Mark Hurd and John Fowler for this important online launch event. Register NOW

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• Serializing persistent/functional data structures

  - by Rob

  Persistent data structures depend on the sharing of structure for efficiency. For an example, see here. How can I preserve the structure sharing when I serialize the data structures and write them to a file or database? If I just naively traverse the datastructures, I'll store the correct values, but I'll lose the structure sharing. I'd like to be able to save data-structures with shared components to a file, restore them, and still have most of the structure shared in the restored data.

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• what do you use for storage discovery / storage management?

  - by lysdexic

  I am looking for some ideas on what would be the best way to discover and manage network storage. Discovery: Any good tools that will scan hosts and storage devices and report back their findings? Maybe using SNMP or WMI? Management: I'm currently looking at Storage Manager by Solar Winds, but it is a bit pricey. Any good open source projects like this? Just looking for ideas of how to get better visibility into the storage infrastructure on this network. It includes a HP Lefthand Iscsi san and EC VNX san. As well as individual hosts with local storage. Thanks for reading and thanks for any input.

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• Azure - Part 4 - Table Storage Service in Windows Azure

  - by Shaun

  In Windows Azure platform there are 3 storage we can use to save our data on the cloud. They are the Table, Blob and Queue. Before the Chinese New Year Microsoft announced that Azure SDK 1.1 had been released and it supports a new type of storage – Drive, which allows us to operate NTFS files on the cloud. I will cover it in the coming few posts but now I would like to talk a bit about the Table Storage.   Concept of Table Storage Service The most common development scenario is to retrieve, create, update and remove data from the data storage. In the normal way we communicate with database. When we attempt to move our application over to the cloud the most common requirement should be have a storage service. Windows Azure provides a in-build service that allow us to storage the structured data, which is called Windows Azure Table Storage Service. The data stored in the table service are like the collection of entities. And the entities are similar to rows or records in the tradtional database. An entity should had a partition key, a row key, a timestamp and set of properties. You can treat the partition key as a group name, the row key as a primary key and the timestamp as the identifer for solving the concurrency problem. Different with a table in a database, the table service does not enforce the schema for tables, which means you can have 2 entities in the same table with different property sets. The partition key is being used for the load balance of the Azure OS and the group entity transaction. As you know in the cloud you will never know which machine is hosting your application and your data. It could be moving based on the transaction weight and the number of the requests. If the Azure OS found that there are many requests connect to your Book entities with the partition key equals “Novel” it will move them to another idle machine to increase the performance. So when choosing the partition key for your entities you need to make sure they indecate the category or gourp information so that the Azure OS can perform the load balance as you wish.   Consuming the Table Although the table service looks like a database, you cannot access it through the way you are using now, neither ADO.NET nor ODBC. The table service exposed itself by ADO.NET Data Service protocol, which allows you can consume it through the RESTful style by Http requests. The Azure SDK provides a sets of classes for us to connect it. There are 2 classes we might need: TableServiceContext and TableServiceEntity. The TableServiceContext inherited from the DataServiceContext, which represents the runtime context of the ADO.NET data service. It provides 4 methods mainly used by us: CreateQuery: It will create a IQueryable instance from a given type of entity. AddObject: Add the specified entity into Table Service. UpdateObject: Update an existing entity in the Table Service. DeleteObject: Delete an entity from the Table Service. Beofre you operate the table service you need to provide the valid account information. It’s something like the connect string of the database but with your account name and the account key when you created the storage service on the Windows Azure Development Portal. After getting the CloudStorageAccount you can create the CloudTableClient instance which provides a set of methods for using the table service. A very useful method would be CreateTableIfNotExist. It will create the table container for you if it’s not exsited. And then you can operate the eneities to that table through the methods I mentioned above. Let me explain a bit more through an exmaple. We always like code rather than sentence.   Straightforward Accessing to the Table Here I would like to build a WCF service on the Windows Azure platform, and for now just one requirement: it would allow the client to create an account entity on the table service. The WCF service would have a method named Register and accept an instance of the account which the client wants to create. After perform some validation it will add the entity into the table service. So the first thing I should do is to create a Cloud Application on my VIstial Studio 2010 RC. (The Azure SDK 1.1 only supports VS2008 and VS2010 RC.) The solution should be like this below. Then I added a configuration items for the storage account through the Settings section under the cloud project. (Double click the Services file under Roles folder and navigate to the Setting section.) This setting will be used when to retrieve my storage account information. Since for now I just in the development phase I will select “UseDevelopmentStorage=true”. And then I navigated to the WebRole.cs file under my WCF project. If you have read my previous posts you would know that this file defines the process when the application start, and terminate on the cloud. What I need to do is to when the application start, set the configuration publisher to load my config file with the config name I specified. So the code would be like below. I removed the original service and contract created by the VS template and add my IAccountService contract and its implementation class - AccountService. And I add the service method Register with the parameters: email, password and it will return a boolean value to indicates the result which is very simple. At this moment if I press F5 the application will be established on my local development fabric and I can see my service runs well through the browser. Let’s implement the service method Rigister, add a new entity to the table service. As I said before the entities you want to store in the table service must have 3 properties: partition key, row key and timespan. You can create a class with these 3 properties. The Azure SDK provides us a base class for that named TableServiceEntity in Microsoft.WindowsAzure.StorageClient namespace. So what we need to do is more simply, create a class named Account and let it derived from the TableServiceEntity. And I need to add my own properties: Email, Password, DateCreated and DateDeleted. The DateDeleted is a nullable date time value to indecate whether this entity had been deleted and when. Do you notice that I missed something here? Yes it’s the partition key and row key I didn’t assigned. The TableServiceEntity base class defined 2 constructors one was a parameter-less constructor which will be used to fill values into the properties from the table service when retrieving data. The other was one with 2 parameters: partition key and row key. As I said below the partition key may affect the load balance and the row key must be unique so here I would like to use the email as the parition key and the email plus a Guid as the row key. OK now we finished the entity class we need to store onto the table service. The next step is to create a data access class for us to add it. Azure SDK gives us a base class for it named TableServiceContext as I mentioned below. So let’s create a class for operate the Account entities. The TableServiceContext need the storage account information for its constructor. It’s the combination of the storage service URI that we will create on Windows Azure platform, and the relevant account name and key. The TableServiceContext will use this information to find the related address and verify the account to operate the storage entities. Hence in my AccountDataContext class I need to override this constructor and pass the storage account into it. All entities will be saved in the table storage with one or many tables which we call them “table containers”. Before we operate an entity we need to make sure that the table container had been created on the storage. There’s a method we can use for that: CloudTableClient.CreateTableIfNotExist. So in the constructor I will perform it firstly to make sure all method will be invoked after the table had been created. Notice that I passed the storage account enpoint URI and the credentials to specify where my storage is located and who am I. Another advise is that, make your entity class name as the same as the table name when create the table. It will increase the performance when you operate it over the cloud especially querying. Since the Register WCF method will add a new account into the table service, here I will create a relevant method to add the account entity. Before implement, I should add a reference - System.Data.Services.Client to the project. This reference provides some common method within the ADO.NET Data Service which can be used in the Windows Azure Table Service. I will use its AddObject method to create my account entity. Since the table service are not fully implemented the ADO.NET Data Service, there are some methods in the System.Data.Services.Client that TableServiceContext doesn’t support, such as AddLinks, etc. Then I implemented the serivce method to add the account entity through the AccountDataContext. You can see in the service implmentation I load the storage account information through my configuration file and created the account table entity from the parameters. Then I created the AccountDataContext. If it’s my first time to invoke this method the constructor of the AccountDataContext will create a table container for me. Then I use Add method to add the account entity into the table. Next, let’s create a farely simple client application to test this service. I created a windows console application and added a service reference to my WCF service. The metadata information of the WCF service cannot be retrieved if it’s deployed on the Windows Azure even though the <serviceMetadata httpGetEnabled="true"/> had been set. If we need to get its metadata we can deploy it on the local development service and then changed the endpoint to the address which is on the cloud. In the client side app.config file I specified the endpoint to the local development fabric address. And the just implement the client to let me input an email and a password then invoke the WCF service to add my acocunt. Let’s run my application and see the result. Of course it should return TRUE to me. And in the local SQL Express I can see the data had been saved in the table.   Summary In this post I explained more about the Windows Azure Table Storage Service. I also created a small application for demostration of how to connect and consume it through the ADO.NET Data Service Managed Library provided within the Azure SDK. I only show how to create an eneity in the storage service. In the next post I would like to explain about how to query the entities with conditions thruogh LINQ. I also would like to refactor my AccountDataContext class to make it dyamic for any kinds of entities.   Hope this helps, Shaun   All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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